Subjects -> TEXTILE INDUSTRIES AND FABRICS (Total: 40 journals)


Showing 1 - 16 of 16 Journals sorted alphabetically
AATCC Journal of Research     Full-text available via subscription   (Followers: 13)
AATCC Review     Full-text available via subscription   (Followers: 4) - Revista Eletrônica de Moda     Open Access  
Asian Journal of Textile     Open Access   (Followers: 12)
Autex Research Journal     Open Access   (Followers: 3)
Cerâmica     Open Access   (Followers: 6)
Composites Science and Technology     Hybrid Journal   (Followers: 245)
Fashion and Textiles     Open Access   (Followers: 18)
Fashion Practice : The Journal of Design, Creative Process & the Fashion     Hybrid Journal   (Followers: 13)
Fibers     Open Access   (Followers: 7)
Fibre Chemistry     Hybrid Journal   (Followers: 4)
Focus on Pigments     Full-text available via subscription   (Followers: 4)
Geosynthetics International     Hybrid Journal   (Followers: 5)
Geotextiles and Geomembranes     Hybrid Journal   (Followers: 6)
Indian Journal of Fibre & Textile Research (IJFTR)     Open Access   (Followers: 15)
International Journal of Fashion Design, Technology and Education     Hybrid Journal   (Followers: 17)
International Journal of Textile Science     Open Access   (Followers: 15)
Journal of Engineered Fibers and Fabrics     Open Access   (Followers: 2)
Journal of Fashion Technology & Textile Engineering     Hybrid Journal   (Followers: 10)
Journal of Industrial Textiles     Hybrid Journal   (Followers: 6)
Journal of Leather Science and Engineering     Open Access   (Followers: 1)
Journal of Natural Fibers     Hybrid Journal   (Followers: 6)
Journal of Textile Design Research and Practice     Full-text available via subscription   (Followers: 7)
Journal of Textile Science & Engineering     Open Access   (Followers: 6)
Journal of The Institution of Engineers (India) : Series E     Hybrid Journal   (Followers: 2)
Journal of the Textile Institute     Hybrid Journal   (Followers: 12)
Research Journal of Textile and Apparel     Full-text available via subscription   (Followers: 1)
Text and Performance Quarterly     Hybrid Journal   (Followers: 5)
Textile History     Hybrid Journal   (Followers: 20)
Textile Progress     Hybrid Journal   (Followers: 6)
Textile Research Journal     Hybrid Journal   (Followers: 14)
Textiles and Clothing Sustainability     Open Access   (Followers: 3)
Textiles and Light Industrial Science and Technology     Open Access   (Followers: 5)
Third Text     Hybrid Journal   (Followers: 11)
Wearables     Open Access   (Followers: 2)
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Journal Cover
Geotextiles and Geomembranes
Journal Prestige (SJR): 1.771
Citation Impact (citeScore): 4
Number of Followers: 6  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0266-1144 - ISSN (Online) 0266-1144
Published by Elsevier Homepage  [3298 journals]
  • Experimental investigations and constitutive modeling of cyclic interface
           shearing between HDPE geomembrane and sandy gravel
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): W.J. Cen, E. Bauer, L.S. Wen, H. Wang, Y.J. Sun This paper presents the results of experimental investigations and constitutive modeling of cyclic interface shearing between HDPE geomembrane and cohesionless sandy gravel. A series of cyclic interface shear tests was performed using a large-scale cyclic shear apparatus with servo controlled system. Particular attention was paid to the influences of the amount of shear-displacement amplitude, number of cycles, shear rate and the normal pressure on the mechanical response. The experimental results show that the path of the shear stress against the cyclic shear displacement is strongly non-linear and forms a closed hysteresis loop, which is pressure dependent, but almost independent of the shear rate. For small shear-displacement amplitudes, the obtained damping ratio is significantly greater than zero, which is different to the behavior usually observed for cyclic soil to soil shearing. In order to describe the pressure dependency of the hysteresis loop using a single set of constitutive parameters, new approximation functions are put forward and embedded into the concept of the Masing rule. Further, a new empirical function is proposed for the damping ratios to capture the experimental data for both small and large cyclic shear-displacement amplitudes. The included model parameters are easy to calibrate and the new functions may also be useful in developing enhanced constitutive models for the simulation of the cyclic interface shear behavior between other geosynthetics and soils.
  • Long-term performance predictions in ground improvements with vacuum
           assisted Prefabricated Vertical Drains
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): P.I. Kumarage, C.T. Gnanendran Investigation into time dependent long-term performance of Prefabricated Vertical Drains (PVDs) combined with vacuum consolidation in thick deposits of clay has been extremely limited. Predicting both settlements and excess pore pressures in such cases has become increasingly challenging when time duration is long-term, e.g. several years. In discussing such matter, finding a suitable model to predict the long-term performance is inevitable. Elasto-plastic analysis models such as Cam-Clay cannot predict long-term time-dependent deformational behaviour in soft soils. In this technical note, a Biot type fully-coupled creep-based elastic viscoplastic (EVP) finite element (FE) numerical model has been extended for application in vacuum consolidation. The vacuum consolidation section of the embankment constructed in Ballina, New South Wales, Australia (hereafter referred as Ballina embankment), is analysed using the model through a unit cell analysis and the numerical predictions are compared with field performance monitoring data up to 1200 days (>3 years). The proposed analysis method for PVD combined with vacuum consolidation involving an EVP model is found to be capable of predicting both short-term and long-term deformational behaviours. Predictions are improved when an exponential function is used for the secondary compression index in the EVP model. Comparison has also been carried out at another location in the embankment where the foundation clay thickness was different to check the precision of the methodology and for better understanding of ground settlement behaviour. Details of the analysis methodology and its validation against field performance data are presented in this note.
  • Radial consolidation of PVD-Installed normally consolidated soil with
           discharge capacity reduction using large-strain theory
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Ba-Phu Nguyen, Yun-Tae Kim The radial consolidation rate of prefabricated vertical drain (PVD)-installed soft deposits is known to be closely related to the PVD discharge capacity, which usually decreases during consolidation. Conventional solutions for radial consolidation of PVD-installed deposits have been developed to consider discharge capacity reduction using small-strain theory, in which the volume compressibility coefficient and soil permeability were assumed to be constant. This paper formulates a general expression for discharge capacity reduction with time in numerical analysis based on large-strain theory. Soil disturbance effects caused by PVD installation, such as a nonlinear distribution for radial hydraulic conductivity, are captured in the proposed solution. The proposed solution was applied to field data from a test embankment at Saga Airport. The proposed solution provides a good result which is close to the measured data.
  • Comparison of the behaviour of various geotextiles used in the filtration
           of clayey sludge: An experimental study
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Guillaume Stoltz, Philippe Delmas, Camille Barral This paper presents the results of an experimental study of various geotextiles used to filter clayey sludge. The use of geotextiles to filter clayey sludge or suspensions of fine particles in water is more complex than that for filtering suspensions of granular soils. In practice, such applications generally use flocculants to postpone the formation of a low-permeability filter cake. The objective of the present study, which does not use flocculants, is to determine how geotextile characteristics affect the capacity of the geotextile to filter clayey sludge. Three key questions are addressed: (1) What are the main differences between vertical and horizontal filtration' (2) How do geotextile characteristics (nature, opening size, permeability, etc.) affect its capacity to filter clayey sludge (3) How do clayey sludge characteristics (i.e., grain size distribution and concentration)' and the type of flow (i.e., constant head or constant flow) affect the filtering capacity of geotextiles' To evaluate the capacity of a geotextile to filter clayey sludge, we propose three relevant criteria and analyse two filtration phases induced by different cake-formation processes (controlled by the geotextile and controlled by the filter cake). To determine the main differences between vertical and horizontal filtration, the settling of fines in the testing device and its influence on the results are analysed and discussed. This study shows that, for the various clayey sludge tested, the geotextiles (needle-punched nonwoven and thermally bonded nonwoven) with the smallest opening sizes (O90 ≤ 60 μm) give the most promising results for filtering fines without the use of flocculants. Of these geotextiles, the thermally bonded nonwoven structure seems to offer the best filtration performance for the largest range of fines concentration in the sludge.
  • Performance of geosynthetic-reinforced flexible pavements in full-scale
           field trials
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Thanongsak Imjai, Kypros Pilakoutas, Maurizio Guadagnini The paper presents the results of a series of full-scale trials carried out in Thailand examining the performance of geosynthetics as reinforcement for flexible pavements. The geosynthetics were embedded at different pavement depths and the structural response was monitored across four test sections by means of strain gauges, pressure sensors, deflection points and deflection plates. The results show that all reinforcement configurations helped reduce the vertical static stresses developed at the base of the pavement by up to 66% and by up to 72% for dynamic stresses. The performance enhancement expected to prolong the lifespan of the base layers. The reinforcement layers closer to the base experienced the highest lateral strains of up to 0.13%, providing evidence that geosynthetics can also effectively reduce lateral spreading. All reinforcement configurations helped enhance rut resistance with maximum traffic benefit ratio (TBR) of 13.70, effectiveness ratio (EF) of 12.70 and minimum rutting reduction ratio (RRR) of 0.74. The best configuration included a geotextile within the asphalt concrete layer and a geogrid under the base layer. Non-linear finite element analyses of the test sections predicted very well the strains and stresses in the pavement. The study provides a benchmark for future studies in this field and concludes that geosynthetics can help increase maintenance periods and extend the lifetime of flexible pavements.
  • Uplift capacity of horizontal anchor plate in geocell reinforced sand
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Awdhesh Kumar Choudhary, Bhardwaj Pandit, G.L. Sivakumar Babu The paper investigates the uplift performance of horizontal anchor plate in geocell reinforced sand through a series of model tests. It is noted that the unreinforced anchor plate undergoes a clear failure at a displacement of about 3% of its width, whereas with the provision of geocell and a layer of geotextile right below the geocell mattress significantly increases the uplift capacity by about 4.5 times higher than that of unreinforced sand and could sustain anchor displacement of more than 60%. Results indicates that the geocell mattress by virtue of its rigidity distributes the uplift load in the lateral directions to a larger area, thereby reducing the stress in the overlying soil mass and hence increases the performance of anchor plate system. The provision of the additional geotextile layer right below the geocell mattress is found to be very effective in increasing the stiffness as well as load carrying capacity of anchor plate system. The optimum size (i.e., width and length) of geocell mattress giving adequate load carrying capacity of anchor plate is found to be 5.4 times of anchor width (5.4B). The comparison of model tests results with 3D numerical analysis shows good agreement, indicating that the proposed model is able to capture the uplift load-displacement behaviour of geocell reinforced anchor plate system.
  • On the shear failure mode of granular column embedded unit cells subjected
           to static and cyclic shear loads
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Cihan Cengiz, Ismail Emrah Kilic, Erol Guler Since the initial conception of geosynthetic encased columns (GECs), exhaustion of column capacity due to vertical loads in bulging and punching failure modes were readily recognized. This lead to a vast majority of the available research on GECs to be about the behavior of columns under the action of vertical loads. Recently, two other likely and perhaps more dominant failure modes for granular columns namely, shear and bending failure modes, were identified. The purpose of this paper is to study the behavior of unit cells containing ordinary stone columns (OSCs) and GECs under static and cyclic lateral loads where shear failure of the column is imminent. 1-g physical tests are conducted with a novel apparatus, designated as Unit Cell Shear Device (UCSD), to model the behavior of the unit cells located close to the toe of an embankment where OSCs and GECs experience significant lateral loading. Overall failure envelope and strength parameters for GECs with varying reinforcement stiffnesses are quantified under static and cyclic lateral loading conditions. The distribution and magnitude of reinforcement strains in horizontal (hoop) and vertical direction of the columns are also considered.
  • Horizontal stiffness evaluation of geogrid-stabilized aggregate using
           shear wave transducers
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Yong-Hoon Byun, Erol Tutumluer, Bin Feng, Joon Han Kim, Mark H. Wayne Lateral restraint resulting from the interlock between geogrid and aggregate is recognized as a primary mechanism governing the load-bearing behavior of a geogrid-stabilized pavement base course. However, the level of geogrid–aggregate interlock and the local stiffness enhancement due to the lateral restraint has not been adequately quantified. In this paper, a new experimental method is proposed to evaluate the stiffness enhancement provided by the interlock of the geogrid–aggregate composite system using shear wave transducers. Repeated load triaxial tests were conducted to determine the resilient modulus and deformation characteristics of both geogrid-stabilized and unstabilized base course aggregates. The stabilized test specimens were evaluated for two geogrid types with rectangular and triangular apertures. For the shear wave measurements, three pairs of bender elements fixed at each mounting base were installed diametrically on the triaxial test specimens at three different locations above the mid-height level, where the horizontal shear modulus profiles of the geogrid-stabilized and unstabilized specimens were determined. The experimental results indicate that the shear modulus profiles obtained as a function of confinement changed significantly based on the geogrid inclusion and type, whereas there were no considerable changes in the resilient moduli from the different specimens, as they were only influenced by the applied stress states. The shear moduli estimated in the vicinity of the geogrid were greater than those at locations farther away from the geogrid, which was installed at the mid-height of the specimen. The shear modulus profiles varied according to the confining stress, and the shear modulus ratio of the stabilized to unstabilized specimens clearly demonstrated the stiffness enhancement provided by the two different geogrids. Accordingly, the shear modulus profiles estimated from the horizontal shear wave measurements of the bender element can be effectively used to determine the mechanically stabilized layer characteristics of a geogrid, and therefore quantify the local stiffness enhancement provided by the geogrid–aggregate interlock.
  • Laboratory tests of electro-osmotic consolidation combined with vacuum
           preloading on kaolinite using electrokinetic geosynthetics
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Lin Zhang, Liming Hu Laboratory tests were conducted on kaolinite to investigate the effectiveness of electro-osmotic consolidation combined with vacuum preloading using electrokinetic geosynthetics (EKG). The results showed that the combined method could remove more water and induce larger surface ground settlements compared with the traditional vacuum preloading or electro-osmotic consolidation. Vacuum preloading was quite effective during the first 4 h, though the electro-osmotic consolidation took a main role in dewatering process after 9 h. The combined method could also hinder the development of cracks, induce higher negative pore water pressure and hence increase the efficiency of electro-osmotic consolidation. The results showed that deep electro-osmotic consolidation technique combined with vacuum preloading could result in significant water removal efficiency along with shorter electrode length. Furthermore, both electro-osmotic consolidation and the combined method could consolidate the soil efficiently with low energy consumption.
  • Closure to "Required unfactored geosynthetic strength of three-dimensional
           reinforced soil structures comprised of cohesive backfills" by Y. Chen et
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Yanbo Chen, Yufeng Gao, Shangchuan Yang, Fei Zhang
  • Scale effect on the behavior of geocell-reinforced soil
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Gh Tavakoli Mehrjardi, R. Behrad, S.N. Moghaddas Tafreshi Existing studies confirmed that the response of geocell-reinforced beds is directly affected by contributory factors, including soil's grains, geocell's characteristics, and surface loading geometries. In this paper, a series of plate load tests has been carried out for the further understanding of the behaviour of geocell-reinforced soil. Four different soil grains sizes, two different geocell's opening sizes and three different loading plate sizes were the considered variables. During the tests, the applied loading and soil surface settlements were recorded to evaluate the systems' response. As it was expected, the geocell-reinforced soil exhibited higher bearing capacity than the unreinforced status, up to 524%. The results further focused on the important role of scale effect on the response of reinforced foundations. The optimum nominal cells size of geocells was obtained about 15 times of medium grain size of soil. Also, it was found that in order to obtain the highest reinforcement benefits, the footing's width should be in the range 13–27 (20 in average) times of medium grain size of the backfill. Finally, to provide more stable and reliable geocell-reinforced backfill, it is recommended that the cells size of geocells should be selected smaller than 0.67 times of footing width.
  • Experimental investigation of the effect of airgaps in preventing
           desiccation of bentonite in geosynthetic clay liners exposed to high
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Bowei Yu, Abbas El-Zein This paper investigates whether the introduction of an airgap above a composite liner made of a geomembrane (GMB) and a Geosynthetic Clay Liner (GCL) can decrease thermal loads on the GCL, reduce the risk of bentonite desiccation and/or help maintain its low hydraulic conductivity. A composite liner, subject to 20 kPa overburden load, over a well graded sand was subjected to a thermal gradient. In addition, to the reference base case in which no airgap was present, two designs included air gaps through the placement of a 10 mm and 20 mm-thick geocomposites (GC) on top of the GCL-GMB, respectively.Temperatures on top of the GCLs were found to be significantly reduced by the presence of air gaps, relative to the reference base case. All three designs resulted in GCL desiccation cracks at the end of the tests, due to the relatively high temperature gradients and low water retention of the subsoil, even in the presence of air gaps. However, X-Ray imaging revealed that crack patterns in bentonite samples from designs with air gaps were finer and narrower. Subsequent rehydration (and permeation tests) with distilled water indicated that significant self-healing of bentonite was in evidence in all three cases. However, while in the absence of an air gap the saturated hydraulic conductivity was found to be 2.8 times its pre-heating value, no significant increase was recorded for other two cases. X-Ray imaging of rehydrated samples confirmed that more effective healing had occurred in samples with an air gap.
  • Discussion on ‘Required unfactored geosynthetic strength of
           three-dimensional reinforced soil structures comprised of cohesive
           backfills’ by Y. Chen et al., (2018)
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): S. Utili The authors of the paper “Required unfactored geosynthetic strength of three-dimensional reinforced soil structures comprised of cohesive backfills” (Chen et al., 2018) have presented an interesting study in which limit analysis (LA) upper bound solutions for 3D failure mechanisms in reinforced cohesive backfills are provided for the first time. The discusser would like to comment on four issues related to the paper: (1) no consideration for the onset of cracks in the slopes (2) use of the presented solutions for forensic analyses (3) underestimation of the level of required reinforcement (4) unsuitability of the presented solutions for design purposes.
  • Strength enhancement of geotextile-reinforced carbonate sand
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Saeed Goodarzi, Habib Shahnazari The mechanical behavior of carbonate sand reinforced with horizontal layers of geotextile is invetigated using a series of drained compression triaxial tests on unreinforced and reinforced samples. The main factors affecting the mechanical behavior such as the number of geotextile layers, their arrangement in specimens, confining pressure, particle size distribution, geotextile type and relative density of samples were examined and discussed in this research. To make a precise comparison between the behavior of reinforced siliceous and carbonate sand, triaxial tests were performed on both types of sands. Results indicate that geotextile inclusion increases the peak strength and strain at failure, and significantly reduces the post-peak strength loss of carbonate specimens. The amount of strength enhancement rises as the number of geotextile layers increases while two other parameters including confining pressure and particle size affect adversely. The strength enhancement of reinforced carbonate sand is greater than the corresponding siliceous sample at high axial strains. Reinforced and unreinforced carbonate specimens exhibit more contractive behavior than their corresponding siliceous samples and tend to dilate at higher axial strains. By increasing the relative density of the samples, the peak strength of reinforced specimens rises due to enhanced interlocking between geotextile layers and sand particles. This process continues as long as the geotextile is not ruptured. The utilization of geotextiles with high mass per unit areas was found to be uneconomical due to slight differences between the strength augmentation of geotextiles with high and low mass per unit areas. It should be noted that geotextile layers limit the lateral expansion of specimens which leads to changing the failure pattern from a shear plane to bulging between the adjacent layers of geotextile.
  • Effect of surcharge loading rate and mobilized load ratio on the
           performance of vacuum–surcharge preloading with PVDs
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Jun Wang, Ziyang Gao, Hongtao Fu, Guangya Ding, Yuanqiang Cai, Xueyu Geng, Changxin Shi The results from three laboratory model tests performed under various vacuum and surcharge loads with PVDs are reported. Different SLRs were adopted to investigate the effect on the consolidation of dredged soil. To measure the lateral displacement, a refitted inclinometer was developed and tested. In the tests, the settlement, lateral displacement, and vane shear strength were measured, and the degree of consolidation (DOC), horizontal coefficient of consolidation (Ch), and bearing capacity were calculated. The results indicate that larger SLR values promote consolidation. The largest vane shear strength, settlement, and Ch values were all obtained under the highest SLR, and the bearing capacity under this SLR was more than double that under the lowest SLR. The DOC was found to increase with the growth of the SLR. However, considering the vacuum pressure was higher in Case-III, the influence of SLR on reinforcement effect may not be so significant.
  • Failure mechanisms of geocell walls and junctions
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Yang Liu, An Deng, Mark Jaksa Geocell panels are honeycomb-like systems used to provide earth reinforcement. Strips of perforated high-density polyethylene sheets, also known as cell-walls, are welded together at locations known as junctions. The cell-wall and junctions are designed to support and transfer tensile and shear loads and the integrity of these is essential for the appropriate performance of geocells in practice. Nevertheless, there is no standardized test procedure to assess the strength of the cell-wall or junction, and limited research has been undertaken regarding the failure mechanisms of geocell panels when subjected to various loading scenarios. This paper aims to examine the responses of geocell junctions and cell-walls under various loading conditions. An extensive testing program was undertaken to assess the geocell junctions, which included uniaxial tensile, shear, peeling and splitting strength tests. The uniaxial tensile strength, trapezoidal tearing strength, and creep tests were carried out on the geocell walls. A ductility ratio was developed to measure the rapidness of failure under different short-term loading scenarios for both the cell-wall and junction. This paper presents the observed failure patterns and an evaluation of the implications of the practical uses of geocells.
  • Water retention of geosynthetics clay liners: Dependence on void ratio and
    • Abstract: Publication date: April 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 2Author(s): Ali Ghavam-Nasiri, Abbas El-Zein, David Airey, R. Kerry Rowe The dependence of the geosynthetic clay liners (GCLs) soil-water characteristic curve (SWCC) on temperature and overburden stress are characterised experimentally. It is shown that changes in void ratio and temperature alter the relationship between suction and moisture content and new forms of existing SWCC equations are developed. To cover a wide suction range, the SWCCs are measured using axis-translation and dew point methods. Based on the available experimental data, both proposed SWCCs are shown to perform well in predicting the effects of void ratio on SWCC along the drying path when compared to the experimental results. It is found that the air-entry value increases as the net vertical stress increases for the experiments under the same temperature. In addition, elevation of temperature reduces retention capacity of the GCL.
  • Geosynthetics for transportation and environmental applications
    • Abstract: Publication date: Available online 21 March 2019Source: Geotextiles and GeomembranesAuthor(s): Jie Han, Shijin Feng
  • Sliding stability and lateral displacement analysis of reinforced soil
           retaining walls
    • Abstract: Publication date: Available online 20 March 2019Source: Geotextiles and GeomembranesAuthor(s): Peng Xu, Kianoosh Hatami Field observations have demonstrated that reinforced soil retaining walls generally have superior seismic performance when compared to traditional gravity retaining walls. However, current design guidelines for reinforced soil retaining walls are typically based on pseudo-static methods of analysis, which involve simplifying assumptions. For instance, the reinforced zone is usually assumed as a rigid body in external stability calculations. As a result, the influences of reinforcement arrangement and properties on the sliding stability and displacement of the wall cannot be accounted for in their design. Additionally, the soil shear strength is assumed to be constant in conventional displacement calculations using the Newmark sliding block method. In this paper, an analysis method is proposed to determine the yield acceleration and lateral displacement of reinforced soil walls that includes soil shear strength mobilization and a two-part wedge planar failure mechanism. The proposed method is validated against the results of laboratory model tests, and influences of factors such as ground acceleration coefficients, and reinforcement and backfill properties on the stability of the wall are examined.
  • Fully transient analytical solution for degradable organic contaminant
           transport through GMB/GCL/AL composite liners
    • Abstract: Publication date: Available online 18 March 2019Source: Geotextiles and GeomembranesAuthor(s): Shi-Jin Feng, Ming-Qing Peng, Hong-Xin Chen, Zhang-Long Chen In this study, analytical solution for degradable organic contaminant transport through a composite liner consisting of a geomembrane (GMB) layer, a geosynthetic clay liner (GCL) and an attenuation layer (AL) is derived by the separation of variables method. The transient contaminant transport in the whole composite liner can be well described avoiding some weird phenomena in existing analytical solutions. The results of parametric study show that GCL has significant effect on improving the barrier efficiency especially for scenarios with high leachate head. The biodegradation and adsorption in GCL have significant influence on the contaminant transport through the composite liner when the half-life of contaminant in GCL is less than 5 years. Otherwise, the effect can be neglected.
  • Design and construction of lightweight EPS geofoam embedded geomaterial
           embankment system for control of settlements
    • Abstract: Publication date: Available online 16 March 2019Source: Geotextiles and GeomembranesAuthor(s): Anand J. Puppala, Pinit Ruttanaporamakul, Surya Sarat Chandra Congress This paper presents a research study on a bridge site located along US highway 67 over SH 174 in Cleburne, Texas, where bridge approach slabs have experienced more than 0.4 m (17 in.) of settlement within a span of 16 years after construction. Many treatment methods attempted to mitigate this problem had proven to be ineffective. As part of novel rehabilitation works, the top of existing fill soil on the embankment was replaced with lightweight expanded polystyrene (EPS) geofoam blocks to alleviate the approach slab settlements. This paper describes initial design and construction details of the rehabilitation works performed on the embankment system along with a focus on the early performance details. Field monitoring studies were conducted for almost three years to study the bump/settlements under the EPS geofoam embankment system. Short term measured settlement data was analyzed with hyperbolic model to predict the long term settlements. Numerical finite element studies attempted in this study showed that settlements could be reasonably predicted by modeling these geofoam embankments. Based on the monitoring and modeling studies, the effectiveness of utilizing EPS geofoam as an embankment fill material was addressed to mitigate the differential settlements under a bridge approach slab.
  • Full scale investigation of GCL damage mechanisms in small earth dam
           retrofit applications under earthquake loading
    • Abstract: Publication date: Available online 16 March 2019Source: Geotextiles and GeomembranesAuthor(s): Yutaka Sawada, Hiroshi Nakazawa, W. Andy Take, Toshinori Kawabata This paper reports results of full scale testing to further explore potential GCL damage mechanisms in earth dam retrofit applications in seismically active areas; in particular, to a) investigate whether shear displacements could reduce the magnitude of GCL panel overlap during earthquake shaking; b) explore the influence of gravel particles on GCL thickness at localised point of contact; and c) observe the consequences of an accidental exposure of an uncovered GCL to short duration rainfall in terms of moisture content and effects during subsequent compaction. The results of these experiments indicate that even under severe shaking no movements were detected at the GCL panel overlap. Whereas gravel particles were observed to locally reduce the thickness of the GCL to 2.2 mm, no plowing of the particle into the GCL occurred due to a lack of shear displacement at the interface, resulting in no localised internal erosion through the barrier. Furthermore, hydration of GCL panels during construction due to surface wetting was observed to result in a state of hydration less than its post-construction state. These results indicate that although each of the three GCL damage mechanisms cannot be ruled out to ever be relevant in practice, the performance of the GCL retrofitted earth dam tested was satisfactory under even severe Level 2 earthquake shaking, and suggests that the retrofitting of small earth dams with GCLs is a promising strategy to improve their static and seismic resistance.
  • Evaluation of moisture reduction in aggregate base by wicking geotextile
           using soil column tests
    • Abstract: Publication date: Available online 15 March 2019Source: Geotextiles and GeomembranesAuthor(s): Jun Guo, Jie Han, Xiong Zhang, Zexia Li This study investigated the distance effect on water reduction by the wicking geotextile in a base course experimentally using three sets of soil column tests. In each set of tests, two soil columns were constructed by compacting well-graded aggregate over a non-wicking woven geotextile and a wicking geotextile. A portion of the geotextile specimen was extended outside of the soil column for evaporation. The changes of the water contents in the soil column were monitored by volumetric water content sensors installed at various depths. The experimental results indicate the capillary drainage by the wicking geotextile effectively reduced water content within the soil column up to a distance from the wicking geotextile (i.e., approximately 200 mm for this specific aggregate with 10% fines). The test results also show that the wicking geotextile could reduce more water content of the aggregate below its optimum water content at a faster rate than the non-wicking geotextile.
  • Geotextile filtration opening size under tension and confinement
    • Abstract: Publication date: Available online 15 March 2019Source: Geotextiles and GeomembranesAuthor(s): Ennio M. Palmeira, Débora L.A. Melo, Isac P. Moraes-Filho Nonwoven geotextiles have been used as filters in geotechnical and geoenvironmental works for half a century. They are easy to install and can be specified to meet the requirements for proper filter performance. There are situations where a geotextile filter may be subjected to tensile loads, which may alter relevant filter properties, such as its filtration opening size. Examples of such situations are silty fence applications, geotextile separators, geotextile tubes and geotextiles under embankments on soft soils. This paper investigates the effects of tensile strains on geotextile pore dimensions. A special equipment and testing technique allowed tests to be carried out on geotextile specimens subjected to tension and confinement. The results obtained showed that the variation in filtration opening size depends on the type of strain state the geotextile is subjected, under which the geotextile pore diameter may remain rather constant or increase significantly. However, confinement reduces the geotextile filtration opening size independent on the strain mobilised. An upper bound for the filtration opening size of strained nonwoven geotextiles is introduced and was satisfactory for the geotextile products tested.
  • Bioengineering of river earth embankment using natural fibre-based
           composite-structured geotextiles
    • Abstract: Publication date: Available online 14 March 2019Source: Geotextiles and GeomembranesAuthor(s): G. Basu, A.N. Roy, P. Sanyal, K. Mitra, L. Mishra, S.K. Ghosh A Jute-HDPE composite structured geotextile was developed to improve the performance of earthen structure of river embankment. The optimized geotextiles (430 g/m2) containing 86% natural component (on weight) having better physical, mechanical (tensile strength, 10 kN/m (machine direction) and 18 kN/m (cross direction), index puncture (163 kN) and CBR (1.5 kN)), hydraulic (AOS 178 μ) and endurance properties than 100% HDPE geotextiles. A coconut fibre geotextile net was placed over jute-polyolefin geotextiles to resist washing-off of loose cover soil until the establishment of vegetation. Placing of continuous seamless geotextile tube (weight 196.2 kg/m) filled with moist river sand at the anchor trench-cum-toe guard assisted in safeguarding from eddies. It was observed that initially closed structure of the geotextile assisted in efficient filtration leading to soil stabilization through compactness of soil layer (14 cm thick). The uniqueness of work lies in conversion of closed structure of geotextiles to open-mesh of HDPE slit film on degradation of jute, remained beneath the cover-soil, through which grass root penetrated the geotextiles sheet and riveted both the layers of soil, the cover and the compacted back layers. The remnant synthetic part thus acts as durable reinforcing element and its increased porosity provides breathability for growth of soil flora and fauna. Bermuda grass turf provided very high nailing strength (658.8 kN/m2) with the soil through intertwining of grass roots with durable synthetic network.
  • Investigation of tensile strength on alkaline treated and untreated kenaf
           geotextile under dry and wet conditions
    • Abstract: Publication date: Available online 14 March 2019Source: Geotextiles and GeomembranesAuthor(s): Mohammad Gharehzadeh Shirazi, Ahmad Safuan A Rashid, Ramli Bin Nazir, Azrin Hani Abdul Rashid, Azman Kassim, Suksun Horpibulsuk Geosynthetics or geotextile is used for aggregate separation, soil reinforcement, filtration, drainage and moisture or liquid barriers in geotechnical applications. Because of the environmental issues, a bio-based material is introduced as a sustainable construction material. The kenaf fibre is a bio-based material available in the tropical countries. It can be potentially used as a geotextile because of its high tensile strength. This paper presents the tensile strength characteristics of kenaf geotextile, manufactured with and without sodium hydroxide (NaOH) treatment. The tensile strength of kenaf geotextile was determined by using the wide-width strip test based on the ASTM D4595-17 standard. Because the kenaf fibre has a high water absorption capability, the effect of wet and dry conditions on tensile behaviour of kenaf textile was studied. Two patterns of woven kenaf with two different opening sizes between their yarns (0 × 0 and 2 × 2 mm)—plain and incline patterns were studied. In addition, the tensile strength of the kenaf geotextiles, buried in natural ground, was examined after a one-year period. The tensile strength of kenaf geotextiles was higher for the smaller spaces between the yarns. Furthermore, the tensile strength and elongation were lower under wet condition. The alkaline treatment (6% concentration of NaOH) significantly improved the tensile strength of the woven kenaf geotextile. The tensile strength of the treated kenaf geotextile was higher than that of the untreated one, for both short and long-term conditions, showing the advantage of NaOH treatment.
  • Required strength of geosynthetics in a reinforced slope with tensile
           strength cut-off subjected to seepage effects
    • Abstract: Publication date: Available online 14 March 2019Source: Geotextiles and GeomembranesAuthor(s): Z.W. Li, X.L. Yang The Mohr-Coulomb (M-C) yield criterion is found to overestimate the tensile strength of cohesive soils. By introducing the concept of tensile strength cut-off, the M-C criterion is modified to reduce or eliminate the tensile strength from the criterion. In this study, a new approach is proposed to investigate the stability of geosynthetic-reinforced slopes in cohesive soils subjected to seepage effects by means of the kinematic approach of limit analysis. The distribution of pore-water pressure is obtained using the numerical modeling software package, FLAC3D. A kinematically admissible failure mechanism is discretized to incorporate the results from the numerical simulation. The strength of geosynthetics required for maintaining the slope stability is evaluated from the work-energy balance equation. An optimization routine is used to seek out the maximum value among all possible results. Design charts providing the normalized required reinforcement under different parameters are plotted for a parametric study and convenient use in engineering. The obtained results show that less reinforcement is required in the presence of soil cohesion, and that the inclusion of the effect of tensile strength cut-off leads to a more conservative solution, which is more obvious in the presence of seepage effects.
  • Bottom ash as a backfill material in reinforced soil structures
    • Abstract: Publication date: Available online 14 March 2019Source: Geotextiles and GeomembranesAuthor(s): Aali Pant, Manoj Datta, G.V. Ramana The paper describes the interface behaviour of bottom ash, obtained from two thermal power plants, and geogrid for possible utilization as a reinforced fill material in reinforced soil structures. Pullout tests were conducted on polyester geogrid embedded in compacted bottom ash samples as per ASTM D6706-01. Locally available natural sand was used as a reference material. The pullout resistance offered by geogrid embedded in bottom ash was almost identical to that in sand. In order to study the influence of placement condition of the material on pullout resistance, test were conducted on uncompacted fill materials. Pullout resistance offered by geogrids embedded in uncompacted specimen reduced by 30–60% than that at the compacted condition.
  • Seismic analysis of geosynthetic-reinforced retaining wall in cohesive
    • Abstract: Publication date: Available online 2 March 2019Source: Geotextiles and GeomembranesAuthor(s): H. Alhajj Chehade, D. Dias, M. Sadek, O. Jenck, F. Hage Chehade Although a cohesionless backfill is recommended for geosynthetic reinforced earth retaining walls, cohesive soil have been widely used in many regions across the globe for economic reasons. This type of backfill exposes the soil to the crack formation that leads to reduce the stability of the system. In this paper, to investigate the internal seismic stability of reinforced earth retaining walls with cracks, the discretization method combined with the upper bound theorem of limit analysis are used. The potential failure mechanism is generated using the point-to-point method. Two types of cracks are considered, a pre-existing crack and a crack formation as a part of the failure mechanism. The use of the discretization method allows the consideration of the vertical spatial variability of the soil properties. A pseudo-dynamic approach is implemented which allows the account of the dynamic characteristics of the ground shaking. The presented method is validated using the conventional limit analysis results of an existing study conducted under static conditions. Once the proposed technique to consider the cracks is validated, a parametric study is conducted to highlight the key parameters effects on the lower bound of the required reinforcement strength.
  • The role of undrained clay soil subgrade properties in controlling
           deformations in geomembranes
    • Abstract: Publication date: Available online 22 February 2019Source: Geotextiles and GeomembranesAuthor(s): B.A. Marcotte, I.R. Fleming Strains were evaluated in a 1.5 mm HDPE geomembrane from overlying coarse uniform drainage gravel when placed above six different compacted clayey soils while keeping pressure, protection, loading rate equal. In each case, a protection layer consisting of 400 g/m2 nonwoven geotextile was placed over the geomembrane. Vertical load of 300 kPa was applied in a relatively short duration. A photogrammetry procedure was used to develop a digital elevation model for each deformed geomembrane surface and the distribution of resulting strain in the geomembrane was evaluated on a percent area basis. The proportion of the overall geomembrane area in which the localised strain exceeded 3% was related to the compacted water content, index soil properties, and undrained shear strength of the six different clayey soils. It was found that an increase in moulding moisture content resulted in increased geomembrane strain in all cases, but the magnitude of the increase in strain varied considerably, depending on the plasticity and silt content of the soil used.
  • Two and three-dimensional numerical analyses of geosynthetic-reinforced
           soil (GRS) piers
    • Abstract: Publication date: Available online 20 February 2019Source: Geotextiles and GeomembranesAuthor(s): Panpan Shen, Jie Han, Jorge G. Zornberg, Amr M. Morsy, Dov Leshchinsky, Burak F. Tanyu, Chao Xu In this study, both two-dimensional (2D) and three-dimensional (3D) numerical analyses were carried out to evaluate the performance of geosynthetic-reinforced soil (GRS) piers. The numerical models were first calibrated and verified against test results available in the literature. A parametric study was then conducted under both 2D and 3D conditions to investigate the influences of reinforcement tensile stiffness, reinforcement vertical spacing, and a combination of reinforcement stiffness and spacing on the performance of GRS piers under vertical loading. Numerical results indicated that the effect of reinforcement spacing was more significant than that of reinforcement stiffness. The use of closely – spaced reinforcement layers resulted in higher global elastic modulus of the GRS pier, smaller lateral displacements of pier facing and volumetric change of the GRS pier, lower and more uniformly-distributed tension in the reinforcement, and larger normalized coefficients of lateral earth pressure. This study concluded that a 2D numerical model gave more conservative results than a 3D model.
  • A novel 2D-3D conversion method for calculating maximum strain of
           geosynthetic reinforcement in pile-supported embankments
    • Abstract: Publication date: Available online 13 February 2019Source: Geotextiles and GeomembranesAuthor(s): Zhen Zhang, Meng Wang, Guan-Bao Ye, Jie Han For design of a geosynthetic-reinforced pile-supported (GRPS) embankment over soft soil, the methods used to calculate strains in geosynthetic reinforcement at a vertical stress were mostly developed based on a plane-strain or two-dimensional (2-D) condition or a strip between two pile caps. These 2-D-based methods cannot accurately predict the strain of geosynthetic reinforcement under a three-dimensional (3-D) condition. In this paper, a series of numerical models were established to compare the maximum strains and vertical deflections (also called sags) of geosynthetic reinforcement under the 2-D and 3-D conditions, considering the following influence factors: soil support, cap shape and pattern, and a cushion layer between cap and reinforcement. The numerical results show that the maximum strain in the geosynthetic reinforcement decreased with an increase of the modulus of subgrade reaction. The 2-D model underestimated the maximum strain and sag in the geosynthetic reinforcement as compared with the 3-D model. The cap shape and pattern had significant influences on the maximum strains in the geosynthetic reinforcements. An empirical method involving the geometric factors of cap shape and pattern, and the soil support was developed to convert the calculated strains of geosynthetic reinforcement in piled embankments under the 2-D condition to those under the 3-D condition and verified through a comparison with the results in the literature.
  • Quantifying the effects of geogrid reinforcement in unbound granular base
    • Abstract: Publication date: Available online 12 February 2019Source: Geotextiles and GeomembranesAuthor(s): Bingye Han, Jianming Ling, Xiang Shu, Weimin Song, Richard L. Boudreau, Wei Hu, Baoshan Huang This study presents an effort to quantify the effects of geogrid reinforcement in the unbound granular base through laboratory testing. Two laboratory tests, the large-scale cyclic shear test and the repeated load triaxial test, were employed. The test protocol of the cyclic shear test was developed by modifying that for the triaxial test. The cyclic shear test was performed by applying a series of cyclic shear stresses to the geogrid-aggregate interface under different normal stresses. Two different types of geogrids were used as reinforcement in unbound granular material. Resilient modulus (MR) from the repeated load triaxial test and a term named resilient interface shear modulus (Gi) from the cyclic shear test was used to characterize the effects of geogrid reinforcement in unbound granular base, respectively. The results of triaxial tests showed that the inclusion of geogrid had a negligible effect on the resilient modulus, indicating that the triaxial resilient modulus test may not be effective in evaluating the geogrid reinforcement in unbound granular materials. Compared to the triaxial resilient modulus test, the cyclic shear test showed great potential in identifying the effects of geogrid reinforcement, with an obvious improvement in the degree of interlocking between geogrids and aggregates.
  • A simplified model for evaluating the hardening behaviour of
           sensor-enabled geobelts during pullout tests
    • Abstract: Publication date: Available online 11 February 2019Source: Geotextiles and GeomembranesAuthor(s): Xin-zhuang Cui, Yi-lin Wang, Kai-wen Liu, Xue-zhi Wang, Qing Jin, Mo-li Zhao, She-qiang Cui Geosynthetics reinforced soil structures (GRSSs) have a tendency to be large and high, resulting in high normal pressures on the geosynthetics. As one of the effective tests for investigating the geosynthetics-soil interaction, pullout tests are traditionally conducted under low normal pressures. This paper reports pullout tests on a type of sensor-enabled geobelts (SEGB) with different normal pressures (5 kPa, 100 kPa, 200 kPa and 400 kPa) applied. The self-measurement function of SEGB allows the study of the working process of SEGB in pullout tests. Moreover, a simplified theoretical model is proposed to investigate the hardening behavior of geobelts in pullout tests. Two models are incorporated in the theoretical model: a bilinear model capturing the full stress-strain curve obtained from uniaxial tensile tests and a hyperbolic model simulating the geobelt-sand interaction from direct shear tests. By means of the finite-difference method, the numerical solutions of the theoretical model are obtained. The proposed model is validated by comparing calculated and measured front pullout force-displacement curves of SEGB under different normal pressures. Further, the computation of the strain distribution of SEGB sandwiched in the sand is compared with tested data with different front pullout force levels for the aforementioned normal pressures. The numerical solutions generally agree well with the experimental results for all tested tensile force and strain ranges; therefore, the proposed simplified model is suitable for evaluating large quasi-plastic deformations of geobelts and the associated interaction with surrounding sand.
  • A closed-form solution for column-supported embankments with geosynthetic
    • Abstract: Publication date: Available online 8 February 2019Source: Geotextiles and GeomembranesAuthor(s): Lin-Shuang Zhao, Wan-Huan Zhou, Xueyu Geng, Ka-Veng Yuen, Behzad Fatahi Soil arching effect results from the non-uniform stiffness in a geosynthetic-reinforced and column-supported embankment system. However, most theoretical models ignore the impact of modulus difference on the calculation of load transfer. In this study, a generalized mathematical model is presented to investigate the soil arching effect, with consideration given to the modulus ratio between columns and the surrounding soil. For simplification, a cylindrical unit cell is drawn to study the deformation compatibility among embankment fills, geosynthetics, columns, and subsoils. A deformed shape function is introduced to describe the relationship between the column and the adjacent soil. The measured data gained from a full-scale test are applied to demonstrate the application of this model. In the parametric study, certain influencing factors, such as column spacing, column length, embankment height, modulus ratio, and tensile strength of geosynthetic reinforcement, are analyzed to investigate the performance of the embankment system. This demonstrates that the inclusion of a geosynthetic reinforcement or enlargement of the modulus ratio can increase the load transfer efficiency. When enhancing the embankment height or applying an additional loading, the height of the load transfer platform tends to be reduced. However, a relatively long column has little impact on the load transfer platform.
  • Swelling behaviour of expansive soils with recycled geofoam granules
           column inclusion
    • Abstract: Publication date: February 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 1Author(s): S. Selvakumar, B. Soundara Structures founded on expansive soils experience large uplift pressure due to the high swelling nature of these soils. In this investigation, an effort is taken to reuse the waste expanded polystyrene (EPS) beads to form geofoam granules column (GGC) and quantify the swelling behaviour of expansive soil with and without GGC inclusion. Several swell tests were carried out in statically compacted soil specimen with uniform thickness of 100 mm placed in a large scale one dimensional consolidation apparatus which can accommodate the California bearing ratio (CBR) mould. Attempts were made to ascertain the performance of GGC inclusion in expansive soil by varying diameters of GGC (25 mm, 40 mm, 50 mm and 75 mm), density of formed GGC (15 kg/m3 and 20 kg/m3) and two placement conditions of soil samples (by varying moisture content). Tests results were analysed which showed that the percentage of swell, swelling pressure and the time rate of swell decreases upon inclusion of GGC and significant reduction is noticed for lesser GGC density. Further, the mechanism of GGCs influence in control swelling of expansive soil is explained with the help of soil-GGC interaction.
  • Biodegradable geotextiles – An overview of existing and potential
    • Abstract: Publication date: February 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 1Author(s): M. Prambauer, C. Wendeler, J. Weitzenböck, C. Burgstaller Geotextiles are a group of mostly thermoplastic polymers, which are processed to flexible material sheets, and are installed on various landscapes for reinforcing or protective purposes. Most applied materials in the field are non-degradable polymers, such as polyolefins or polyesters, which can implicate environmental problems concerning soil pollution and accumulation of micro plastics. Because of these drawbacks, for some applications time-consuming re-collection of the material becomes necessary. Hence, the development of more environmentally friendly and biodegradable geotextiles is of interest for several application purposes. In this review biodegradable alternatives to the conventional polymeric geotextile fibers are discussed. In general, there are two material classes available, which are natural fibers and biodegradable polymers. While there is already quite a number of natural-fiber-based geotextiles available on the market, the idea of applying industrial biopolymers for this purpose is relatively unexplored. Geotextile fabrics, made of plant fibers, represent a promising approach and were already successfully installed in several applications. However, the use of natural fibers also entails some limitations regarding water uptake and stability. Therefore, the potential use of a different material class, which comprises degradable, thermoplastic biopolymers, is discussed in this overview as well. There is only little information available on the use of these biopolymers in connection with geotextiles, thus their suitability regarding biodegradation, price and mechanical properties were evaluated.
  • Hydro-mechanical behavior of a lateritic fiber-soil composite as a waste
           containment liner
    • Abstract: Publication date: February 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 1Author(s): M. Ehrlich, M.S.S. Almeida, D. Curcio In waste disposal landfill projects, the hydraulic conductivity of the barriers is a major consideration. The use of fibers mixed with backfill may improve the overall performance of the barriers. Fiber-soil composites show a more resistant and ductile behavior than the soil alone. The presence of fibers may reduce cracking problems related to shrinkage or traction in liners or covers. In this study, laboratory tests were performed to evaluate the use of fiber-soil composites as a containing barrier. Hydraulic conductivity and diametral-compression tests were carried out on PET fiber reinforced and unreinforced compacted soil specimens. The tests were conducted under confinement conditions similar to those found in the field. Diametral-compression tests were used to induce cracks in the specimens. Hydraulic conductivity was measured at different stages during the diametral loading. In the tests performed under low confinement pressure (10 kPa), the crack openings led to a significant increase in hydraulic conductivity. The results showed that the addition of fibers increases the tensile strength of the soil-fiber mass and delays the opening of cracks. Moreover, in the tests under high confinement pressure (100 kPa), a decrease in hydraulic conductivity occurred at all stages of the diametral load application.
  • Field study of a retaining wall constructed with clay-filled soilbags
    • Abstract: Publication date: February 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 1Author(s): Sihong Liu, Kewei Fan, Siyuan Xu This paper presents a field study of constructing retaining walls using soilbags that are formed by filling the excavated clayey soils into woven bags (geosynthetics). The strength and deformation of the soilbags filled with clayey soils were studied via laboratory tests. A 100 m testing retaining wall was constructed with soilbags in a waterway project. The lateral deformation, the lateral pressures and the surface settlements of the testing retaining wall were monitored during construction and after 7 months operation. The results show that the soilbags can increase the strength of clayey soils. After 7 months of the completion, the lateral deformation and the surface settlement of the testing retaining wall tend to be stable with the maximum values of 29.4 cm and 19.2 cm, respectively. The lateral earth pressure on the front retaining structure could be positively reduced owing to the interlayer's friction of soilbags. Compared to the conventional gravity concrete retaining wall, about 38% construction cost was saved in the 100 m testing retaining wall.
  • Investigating the mechanism of downslope bentonite erosion in GCL liners
           using X-Ray CT
    • Abstract: Publication date: February 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 1Author(s): T. Mukunoki, K. Sato, J. Fukushima, K. Shida, W.A. Take Exposed composite GMB-GCL liners are at risk of downslope bentonite erosion caused by the release of low ionic strength condensed water onto the top surface of the GCL following daily solar heating. This paper investigates the use of X-ray computed tomography (X-ray CT) to quantify the thinning of the bentonite layer and the application of X-ray diffraction techniques (XRD) to investigate the changes in clay chemistry (if any) of the bentonite from the virgin GCL to the eroded bentonite. The effect of specimen size and scanning orientation was investigated resulting in a revised testing procedure in which the CT scanning orientation was changed from horizontal to vertical to permit a longer test specimen which was also sealed at the bottom edge to minimise the edge boundary condition. The X-ray CT results provide highly visual evidence that a) bentonite thinning immediately under the upper cover geotextile is the initial location of erosion, and b) the bentonite core erodes at a significantly higher rate when not covered by a geotextile than when covered by a geotextile. These observations indicate that the upper geotextile of the GCL plays a significant role in controlling the rate of bentonite erosion. Finally, a comparison of the virgin and runoff bentonite properties was conducted to investigate potential changes in swell index, X-ray diffraction results, and concentration of Na and Ca cations. The runoff bentonite was observed to had a significantly higher swell index (40 ml/2 g) than the virgin bentonite (28 ml/2 g) and lower Na and Ca concentrations. This finding is consistent with the observation from XRD analyses of the runoff bentonite which illustrate that the clay fraction of the bentonite is preferentially eroded by the application of DI water.
  • Interface transmissivity of conventional and multicomponent GCLs for three
    • Abstract: Publication date: February 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 1Author(s): A.Y. AbdelRazek, R. Kerry Rowe A laboratory investigation of the interface transmissivity is reported for five different geosynthetic clay liners (GCLs) and a range of different geomembranes (GMBs) for a range of stresses from 10 to 150 kPa. The GCLs were prehydrated under normal stress before permeation. The GCLs examined comprised three multicomponent (a smooth coated, a smooth laminated, and textured coated) and two conventional (one with granular and one with powdered sodium bentonite) GCLs. The effect of a 4 mm circular defect in the coating of a multicomponent GCL directly below the 10 mm diameter hole in the GMB is investigated. The effect of GMB stiffness and texture is examined. Additionally, the effect of hydration and permeation of smooth coated GCL with highly saline solution and synthetic landfill leachate (SL3) is presented. It is shown that the 2-week interface transmissivity (θ2-week) can be one to two orders of magnitude higher than steady-state interface transmissivity (θ steady-state) at low stresses (10 kPa–50 kPa), whereas at high stresses (150 kPa) the variation is substantially less. For a smooth coated GCL hydrated and permeated with reverse osmosis (RO) water, GMB stiffness and texture has a limited effect on interface transmissivity when the coating is placed in contact with GMB at normal stresses of 10 kPa–150 kPa, whereas coating indentations result in much high interface transmissivity when placed in contact with GMB. GCL prehydration and permeation with highly saline solutions leads to higher interface transmissivity compared to RO water. With a 4.0 mm defect in the coating, the interface transmissivity between the coating and woven geotextile is higher than that between the coating and GMB for the stress levels and GCL examined.
  • Application of the two-layer system theory to calculate the settlements
           and vertical stress propagation in soil reinforcement with geocell
    • Abstract: Publication date: February 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 1Author(s): J.O. Avesani Neto This paper presents a methodology for determining the surface settlements of the geocell-reinforced soil layer and the vertical stresses propagated to the foundation subgrade at the layers interface, on the subgrade. Based on the theory of equivalent thicknesses, which is an approximation of the theory of elasticity for layered systems, a generalized equation for determining settlements was proposed in a two-layer system composed of geocell-reinforced soil layer over the subgrade. The equation obtained is dependent only on the relations between the elastic parameters of these two layers, such as the deformation moduli and Poisson's ratio, and geometric parameters, such as geocell layer thickness and loading width,. The proposed equation generated very close results with rigorous solutions of the two-layer system from the theory of elasticity. It was applied, together with rigorous methods, in an instrumented field Plate load test allowing the determination of the geocell-reinforced soil layer modulus of deformation by retro analysis and the vertical stresses propagated to the subgrade. The results showed that the two-layer system theory from theories of elasticity and equivalent thicknesses can be used in a simple and efficient way for determining settlements and the propagation of vertical stresses. The proposed methodology also satisfactorily calculated these results when compared with the rigorous methods and with the values obtained in the field test.
  • Behavior evaluation of geogrid-reinforced ballast-subballast interface
           under shear condition
    • Abstract: Publication date: February 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 1Author(s): Kumari Sweta, Syed Khaja Karimullah Hussaini The effective functioning of a railway track under operating conditions depends largely on the performance of various rail track interfaces (e.g. ballast-subballast interface, subballast-subgrade interface). In this context, a series of large-scale direct shear tests were conducted to investigate the shear behavior of unreinforced and geogrid-reinforced ballast-subballast interfaces at different normal stresses (σn) and rates of shearing (Sr). Fresh granite ballast and subballast having average particle size (D50) of 42 mm and 3.5 mm respectively, and five geogrids with different aperture shapes and sizes were used in this study. Tests were performed at different normal stresses (σn) ranging from 20 to 100 kPa and shearing rates (Sr) ranging from 2.5 to 10.0 mm/min. The laboratory test results confirmed that the shear strength of ballast-subballast interface was highly influenced by the applied normal stress (σn) and rate of shearing (Sr). The friction angle (φ) of unreinforced ballast-subballast interface was found to decrease from 63.24° to 47.82° and dilation angle (ψ) from 14.56° to 5.23° as the values of σn and Sr increased from 20 to 100 kPa and 2.5–10.0 mm/min, respectively. Further, the breakage of ballast (Bg) was found to increase from 2.84 to 6.69%. However, geogrid inclusions enhanced the shear strength of the ballast-subballast interface and also reduced the extent of Bg. The results indicate that it is possible to establish a relationship between the friction angle (φ) and breakage of ballast (Bg), wherein the friction angle (φ) of both unreinforced and geogrid-reinforced interfaces reduces with the increase in breakage (Bg). The interface efficiency factor, defined as the ratio of the shear strength of the geogrid-reinforced ballast-subballast interface to the original shear strength of ballast-subballast interface varies from 1.04 to 1.22. Moreover, the current study revealed that the shear behavior of ballast-subballast interface was influenced by geogrid aperture size (A).
  • Effect of vacuum removal on consolidation settlement under a combined
           vacuum and surcharge preloading
    • Abstract: Publication date: February 2019Source: Geotextiles and Geomembranes, Volume 47, Issue 1Author(s): Pengpeng Ni, Kai Xu, Guoxiong Mei, Yanlin Zhao The combined vacuum and surcharge preloading technique is extensively used to accelerate the consolidation process of subsoils. The effect of vacuum pressure is often considered as a loading/unloading cycle of mean effective stress, such that elastic rebound occurs after vacuum removal, which cannot explain the observed postconstruction settlement in the field. In this study, the stress state of subsoils subject to vacuum and surcharge preloading is analyzed and decomposed into two components: (a) geostatic consolidation at a different depth, and (b) loading/unloading in the minor principal stress direction. A series of consolidated drained triaxial tests is conducted to simulate the soil behaviour after vacuum removal. Results show that the contribution of unloading in the minor principal stress direction outweighs the magnitude of elastic rebound after vacuum removal, and hence continued settlement dominates. A field case for highways is provided to further demonstrate the proposed mechanism.
  • Magnitude and significance of tensile strains in geomembrane landfill
    • Abstract: Publication date: Available online 30 January 2019Source: Geotextiles and GeomembranesAuthor(s): R. Kerry Rowe, Yan Yu The implications of the tensile stress/strain developed in high density polyethylene (HDPE) geomembranes (GMB) is explored in the context of a reduction in stress crack resistance due to ageing in contact with leachate in a municipal solid waste (MSW) landfill. The experimental evidence of GMB cracking and ultimately failure when subject to excessive tensile strains is discussed to highlight the need to limit the maximum tensile strain sustained by an HDPE GMB to an acceptable level if good long-term performance is to be ensured. The effect of both local GMB indentations induced by gravel in an overlying drainage layer or an underlying clay liner on tensile strain is reviewed. In addition, the tensile strains caused by down-drag in the GMB on side slopes with settlement of the waste is examined. The key research related to tensile strains developed in GMBs from these sources is reviewed and new data presented. It is shown that an appropriate protection layer over the GMB can limit local GMB tensile strains to less than 3% and that the selection of a suitable slope inclination and stiffness of a geotextile reinforcement layer can limit the GMB strains due to down-drag to less than 2% and geotextile strains to less than 4% after long-term waste settlement.
  • Experimental and theoretical studies on the ultimate bearing capacity of
           geogrid-reinforced sand
    • Abstract: Publication date: Available online 23 January 2019Source: Geotextiles and GeomembranesAuthor(s): Chao Xu, Cheng Liang, Panpan Shen Geosynthetic reinforced soil (GRS) structures have gained popularity in replacing concrete rigid piles as abutments to support medium or small-spanned bridge superstructures in recent years. This study conducted 13 model tests to investigate the ultimate bearing capacity of the GRS mass when sand was used as backfill soil. The GRS mass was constructed and loaded to failure under a plane strain condition. Test results were compared with two analytical solutions available in literature. This study also proposed an analytical model for predicting the ultimate bearing capacity of the GRS mass based on the Mohr-Coulomb failure criterion. The failure surface of the GRS mass was described by the Rankine failure surface. The effects of compaction and reinforcement tension were equivalent to increased confining pressures to account for the reinforcing effects of the geosynthetic reinforcement. The proposed model was verified by the results of the model tests conducted in this study and reported in literature. Results indicated that the proposed model was more capable of predicting the ultimate bearing capacity of the GRS mass than the other two analytical solutions available in literature. The proposed model can be used to predict the ultimate bearing capacity of GRS structures when sand was used as backfill material. In addition, a parametric study was conducted to investigate the effects of friction angle of backfill soil, reinforcement spacing, reinforcement strength, and reinforcement stiffness on the ultimate bearing capacity of the GRS mass calculated with and without compaction effects. Results showed that the ultimate bearing capacity of the GRS mass was significantly affected by the friction angle of backfill soil, reinforcement spacing and strength. Compaction effects resulted in an increase in the ultimate bearing capacity of the GRS mass.
  • Local stiffness characteristic of geogrid-stabilized aggregate in relation
           to accumulated permanent deformation behavior
    • Abstract: Publication date: Available online 23 January 2019Source: Geotextiles and GeomembranesAuthor(s): Yong-Hoon Byun, Erol Tutumluer Accumulated permanent deformation is the primary source of damage in a pavement unbound aggregate base layer. Mechanical stabilization with the help of a geogrid installed in unbound aggregate base provides lateral restraint to the flexible pavement, however, the local stiffness characteristic of geogrid-stabilized aggregate in relation to permanent deformation behavior is not clearly known. This study presents variations in shear modulus properties of geogrid-stabilized and unstabilized aggregate specimens in relation to permanent deformation accumulation. To characterize the local stiffnesses near and far away from geogrid, two pairs of bender elements were inserted in triaxial specimens as shear wave transducers. With the number of load cycles, the variations in the shear wave velocities at two different specimen heights were monitored. The test results show that, after the specimen preparation, the shear modulus near the geogrid was greater than that far away from the geogrid. Further, the shear modulus estimated at both levels of unstabilized specimen was similar to that estimated far away from geogrid in the mechanically stabilized specimen. This study demonstrates that the local stiffness of aggregate can be monitored by using the bender elements in relation to trends in permanent deformation behavior, and suggests the bender element systems can be effectively used to validate the benefits of geogrid stabilization by quantifying local stiffnesses at various levels of accumulated permanent deformation.
  • Corner reinforced slopes: Required strength and length of reinforcement
           based on internal stability
    • Abstract: Publication date: Available online 21 January 2019Source: Geotextiles and GeomembranesAuthor(s): Fei Zhang, Dov Leshchinsky, Yufeng Gao, Shangchuan Yang This paper develops an analysis procedure for turning corner in Geosynthetic-Reinforced Soil Structures (GRSS's). The procedure includes the calculations of the required strength and length of the reinforcement for internal stability. The calculations are based on the variational limit equilibrium analysis of three-dimensional (3D) stability of slopes. Seismic effects are also considered using the pseudo-static method. Results are presented in a condensed form of design charts, providing a simple tool to determine the required tensile strength and embedment length of the reinforcement. Two examples are given to demonstrate the use of the design charts. Compared with the conventional design based on plane-strain analysis, the presented design procedure yields longer reinforcement for the 3D internal stability of the corners. Generally, 3D design requires longer reinforcement than 2D as the seismic acceleration increases. The trend of obtained result is in good agreement with performance observations related to corners reported in commentary of AASHTO.
  • Microscale investigation into mechanical behaviors of heat-bonded nonwoven
           geotextile using DEM
    • Abstract: Publication date: Available online 18 January 2019Source: Geotextiles and GeomembranesAuthor(s): Hong-Xin Chen, Xin Liu, Shi-Jin Feng, Jie-Ni Chen, Dong-Mei Zhang, Annan Zhou Heat-bonded nonwoven geotextiles (HBNGs) made from synthetic fibers are widely used in engineering practices. One of the challenges on the way is to link the properties of fibers and the fabric's microstructure to the deformation and failure mechanisms of HBNGs. In this study, a random distribution geometry method was developed to reproduce the complex fibrous structure of HBNG. A piecewise linear model was adopted to reproduce the nonlinear stress-strain relationships of single fibers. The present method has been successfully applied in the simulation of uniaxial and biaxial tensile tests and puncture test. The orientation distribution of fibers and the mechanical behaviors (e.g., deformation, strain localization, force-strain relationship) of HBNG specimen were reasonably simulated. Specifically, the hourglass shape during uniaxial tensile test, the axisymmetric deformation pattern during biaxial tensile test and the trumpet shape during puncture test were all well reproduced. The present method provides an applicable tool to study the complicated mechanical behaviors of HBNG and is also helpful to obtain a better understanding of its deformation and failure mechanisms.
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Heriot-Watt University
Edinburgh, EH14 4AS, UK
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