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 Bulletin of Engineering Geology and the EnvironmentJournal Prestige (SJR): 0.896 Citation Impact (citeScore): 2Number of Followers: 15      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1435-9537 - ISSN (Online) 1435-9529 Published by Springer-Verlag  [2658 journals]
• Correction to: Evolution of hydro‑mechanical behaviours and its
influence on slope stability for a post‑earthquake landslide:
implications for prolonged landslide activity

PubDate: 2021-10-13

• Correction to: Effect of frost damage on the pore interconnectivity of
porous rocks by spontaneous imbibition method

PubDate: 2021-10-11

• Influence of rock powder on the behaviour of an organic soil

Abstract: This paper aims to present the use of rock powder as an agent to improve the behaviour of organic soil. The rock powder, a waste material, was mixed with the organic soil at different contents, namely 10%, 20%, 35%, and 50% by dry weight of the mixture. Experiments have been conducted in fall cone, compaction, unconfined compression strength, and oedometer testing apparatuses. The influence of 50% rock powder content on the Atterberg limits and undrained shear strength (su) of organic soil was to be decreased of the order of 30% and 80%, respectively. The results have shown a marked effect of rock powder inclusion on compaction tests with a substantial increase in dry unit weight (γ) and a decrease in optimum moisture content (wopt). Although unconfined compressive strength (qu) values have increased slightly with the addition of rock powder, the dramatic decrease observed in energy absorption values indicates that the additive gives the mixture a relatively brittle behaviour. It is also among the observations reached that the waste rock powder inclusion affects consolidation characteristics at varying rates, with a substantial decrease in compression index (cc), swelling index (cs), initial void ratio (eo), and volumetric compressibility (mv), and increase in the coefficient of consolidation (cv) up to about 25%. The results are presented for reducing the environmental impact of rock powder by treating organic soil.
PubDate: 2021-10-11

• Hazard assessment of earthquake-induced landslides by using permanent
displacement model considering near-fault pulse-like ground motions

Abstract: A permanent displacement model (PDM) is often used for hazard assessment of earthquake-induced landslides (ELHA) at regional scale. Pulse-like ground motions (PLGM) are rarely considered in the existing PDMs, although they have been proved to have significant influence on the initiation of landslides in near-fault area. In this paper, taking an area affected by 1994 Mw 6.7 Northridge earthquake as an example, 3 PDMs composed of PLGM, and 11 other models were selected to compare and verify the effects of PLGM. According to the results of multiple evaluation metrics such as the ground failures captured (%GFC), receiver operating characteristics (ROC), and quality sum (Qs), it indicates that the PDMs composed of PLGM use less ground motion records, but the accuracy of evaluation results is higher. This shows that PLGM have significant effect on ELHA. The ELHA method considering the near-fault PLGM was applied to a certain area along the Sichuan-Tibet Railway. The results show that the displacement model considering PLGM predicted more landslides cells. Among them, 8.45% of the slopes are in the extremely high hazard area, and about 30% of the extremely high hazard area is within 5 km of the railway. The slope with high hazard of earthquake-induced landslide can be investigated and protected in advance to avoid casualties and property losses.
PubDate: 2021-10-11

• Rockburst intensity evaluation by a novel systematic and evolved approach:
machine learning booster and application

Abstract: Prediction of rockburst in underground engineering is of significance as it is close to the safety of support structures, personnel, and working environments. To improve the accuracy of rockburst classification, this paper proposed an ensemble classifier RF-FA model in which the random forest classifier (RF) and firefly algorithm (FA) were combined to achieve the optimum performance on rockburst prediction. Five key parameters of surrounding rock, i.e., the depth H, the maximum tangential stress σθ, the uniaxial compressive strength σc, the tensile strength σt, and the elastic energy index Wet, are selected as input variables while the rockburst intensity including none, light, moderate, and strong classes was chosen as output. A total of 279 cases worldwide were collected and used for train and test the proposed RF-FA model. The results showed that the FA can optimize the hyperparameters of RF efficiently and the optimum model exhibited a high performance on rockburst data from the independent test set and new engineering projects. The feature importance obtained by the ensemble RF-FA model indicated that the elastic energy index plays the most important role in rockburst. Besides, the proposed model showed much better accuracy on rockburst classification compared with previously existing RF models and empirical criteria, which means it is a useful and robust tool for rockburst prediction.
PubDate: 2021-10-09

• Improved dataset for establishing novel relationships between compaction
characteristics and physical properties of soils

Abstract: In the past, several studies were performed for assessment of compaction properties of different types of soils. A comprehensive evaluation of compaction parameters is essential for engineers working in practice. The main goals of compaction in landfills including highways and railways can be listed as reducing permeability and developing strength as well as enhancing the stability of soils. Literature includes various correlations proposed for establishing the link between the compaction properties of soils and Atterberg limits. Besides, many researchers performed laboratory studies to obtain correlations among soil index, strength, compression, and compaction characteristics of soils. In this study, in addition to authors’ own data composed of compaction, strength, index, and consistency identifiers of sand-clay mixtures from three different types of sands (S1, S2, Q) and two types of clays (kaolinite and bentonite), a vast amount of data from past studies including tests on different types of soils around the world were also compiled. The global database was evaluated to propose novel correlative relationships among compaction characteristics, grain size distribution properties, and Atterberg limits. Proposed equations and relationships for estimation of compaction characteristics seem to be viable to use in practice.
PubDate: 2021-10-07

• Displacement prediction of step-like landslides based on feature
optimization and VMD-Bi-LSTM: a case study of the Bazimen and Baishuihe
landslides in the Three Gorges, China

Abstract: Displacement prediction is critical for the early detection of landslides, and the empirical, statistical, and machine learning models have been commonly used. In the Three Gorges reservoir area (TGRA), many landslides experience step-like deformations due to the periodic change of influencing factors. In this study, a novel and dynamic model is proposed to predict the displacements of step-like landslides. Two typical landslides in the TGRA are taken as case studies. Variational mode decomposition (VMD) is used to decompose the cumulative displacements into stochastic, periodic, and trend components. The influencing factors are decomposed into low-frequency and high-frequency components. Two principles, including the physical connotation and minimum sample entropy, are employed to optimize the VMD parameters. The trend displacement is fitted and predicted by a polynomial expression with an optimized order, and the periodic and stochastic displacements are dynamically modeled by the bidirectional long short-term memory (LSTM) model. The cumulative displacement prediction is the addition of the three displacement components. The proposed model has been shown to exhibit superior performance in the displacement prediction of step-like landslides. To achieve acceptable prediction, a size ratio between the training and testing datasets greater than or equal to five is recommended. The min–max and zero-mean normalizations are applicable to the data preprocessing of this work.
PubDate: 2021-10-05

• Characteristics and control technology of face-end roof leaks subjected to
repeated mining in close-distance coal seams

Abstract: The roof usually collapses when exposed to the repeated underground mining; this will potentially lead to the instability of coal wall and even cause serious mining disasters. Based on this specific mining hazard, this work investigates the roof leak characteristics and corresponding control technology based on a coal mine in Guizhou province, China. The theoretical analysis, numerical simulation, and physical testing were carried out. By establishing a physical model, the roof structure and roof “pressure” law under repeated mining are studied, and the instable conditions of face-end roof are analyzed, so as to determine the influencing factors of face-end roof instability. By analyzing different roof structures, the working resistance of hydraulic support with stable face-end roof under repeated mining is determined. The leakage of face-end roof under different support working resistance, tip-to-face distance, and surrounding rock strength is simulated, and different methods are proposed to control face-end roof leaks. The results show that in the process of 17# coal seam mining, the roof collapse is serious, the roof pressure is frequent, and the broken roof instability would form the “granular arch” structure. Through the analysis of the roof structure, the tip-to-face distance, the strength of granular arch structure, and the working resistance of the hydraulic support affect the stability of the face-end roof. Using UDEC simulation software, it is obtained that the higher the strength of roof and surrounding rock, the smaller the tip-to-face distance, the more stable the face-end roof is. The prevention measures such as strengthening the broken face-end roof under repeated mining, improving the support strength of the working face hydraulic support and controlling the reasonable tip-to-face distance are put forward. Through field application, the face-end roof leaks have been effectively controlled, which has played a good reference for the prevention and control of face-end roof leaks under repeated mining.
PubDate: 2021-10-05

• Effect of frost damage on the pore interconnectivity of porous rocks by
spontaneous imbibition method

Abstract: Frost damage due to freeze–thaw activity in hard rocks is a process that influences the appearance of the geo-relief of the landscape. Methods of frost damage assessment in rocks are based on parameters obtained mainly by destructive testing of samples. In this paper, nondestructive methods for the determination of pore connectivity as an important topological parameter affecting the migration of the fluid in rock material, as well as its variability due to freeze–thaw cycling, were employed. Tuff, andesite, and travertine, as well as two types of sandstones, were subjected to spontaneous imbibition testing. Based on the variation of the diffusion front with time, the slope of imbibition curve- C(I) was estimated and compared before and after 100 freeze–thaw thermal cycles. The samples were tested within a temperature range from − 10 to 10 °C in a fully saturated state in a controlled thermal chamber. Imbibition slopes were analyzed for fast (0.1–1 min) and medium (1–10 min) time intervals due to the variable petrophysical properties of the tested rocks. A considerable increase in imbibition slopes was detected, making the C(I) value a promising parameter that characterizes the interconnectivity of pores inside porous rocks. This parameter, in combination with the length of ice crystallization tc obtained from a thermistor probe located in the center of saturated dummy samples prepared from the same rock type subjected to freeze–thaw cycling, is capable of giving important indications of the degradability of rocks due to frost damage.
PubDate: 2021-10-05

• Evolution of hydro-mechanical behaviours and its influence on slope
stability for a post-earthquake landslide: implications for prolonged
landslide activity

Abstract: There has been considerable research on the prolonged effects and evolution of post-earthquake landslides, as they are of significance for disaster relief and rebuilding plans in earthquake-impacted regions. There is a need to better quantify these prolonged effects and evolution based on the hydro-mechanical mechanisms of post-earthquake landslides. This study investigated the evolution of the hydro-mechanical behaviour and parameters of a single landslide by integrating experimental and theoretical analyses. Analyses were undertaken using a time series of in situ monitoring data over five hydrological years on a single landslide site in the Baisha River basin of Dujiangyan, in the Wenchuan earthquake region, China. Results indicated a linear increase in the angle of internal friction under prolonged effects, while soil cohesion decreased non-linearly, gradually approaching a lower limit. The saturated hydraulic conductivity ( $${K}_{s}$$ ) increased, and the soil residual water content ( $${\theta }_{r}$$ ) evolution curve conformed to the Boltzmann function distribution model. The soil–water characteristic curve parameters gradually increased. Based on the hydro-mechanical parameter evolution, the spatiotemporal decay of the landslide over the next decade under extreme rainfall conditions was predicted using the rainfall slope stability models and TRIGRS. This paper proposed a mechanistic explanation for the prolonged effects of a post-earthquake landslide in response to rainfall. Furthermore, it provided a reliable theoretical basis for the early warning and prevention of such landslides.
PubDate: 2021-10-04

• Investigation on the evolution characteristics and transfer mechanism of
surrounding rock pressure for a hard-rock tunnel under high geo-stress:
case study on the Erlang Mountain Tunnel, China

Abstract: Similar to the squeezing soft-rock tunnel, the surrounding rock pressure for a deep-buried hard-rock tunnel under high geo-stress also possesses certain long-term evolution characteristics, which have a significant impact on the safety performance of the supporting structures. This paper investigated the evolution characteristics and transfer mechanism of the surrounding rock pressure for a deep-buried hard-rock tunnel through the combinations of the field measurements and numerical simulation. Firstly, the triaxial compression and uniaxial creep tests for granite samples indicated that the hard-brittle rock could exhibit the rheological properties under high geo-stress. Secondly, the field measurements showed that the surrounding rock pressure continued to increase throughout a period of 1200 days. Thirdly, a new composite viscoelastic-plastic creep constitutive model was used to calculate the creep damage degree and scope of the surrounding rock. The results showed that the evolution characteristics of the surrounding rock pressure can be divided into three typical stages, i.e., phase I: rapid growth stage; phase I : decelerating growth stage; and phase III: basically stable stage. From the beginning of phase II to the end of phase III (about 1100 days), the pressure on the supporting structures increased by nearly 40% compared to phase I (about 50 ~ 150 days), and the average pressure-sharing proportions of the primary support and the secondary lining finally were stabilized at 0.6 and 0.4, respectively. The damage of surrounding rock was distributed mainly from the haunch to the vault and the bottom, with the degree and scope of the bottom being the most serious.
PubDate: 2021-10-04

• Effect of EPS beads in lightening a typical zeolite and cement-treated
sand

Abstract: The current study aims to assess the influence of EPS beads inclusion on the strength properties of stabilized poorly-graded sands. Various contents of zeolite and cement as stabilizing agents, with the total amounts of 4, 8, and 12% by dry soil weight, and also 0, 0.25, and 0.5% weight ratios of EPS beads ( $$\eta$$ ) are examined. Zeolite is opted among a variety of pozzolanic materials so as to replace a part of cement (0, 10, 30, 50, 70, and 90%) due to its superior environmentally friendly properties. The stress–strain behavior, unconfined compressive strength (UCS), peak strain energy (Eu), and California bearing capacity (CBR) of the zeolite and cement-treated sand-EPS beads mixtures are investigated through several mechanical tests. Results showed that zeolite incorporation (with the optimum value of 30% replacement) improves the UCS and CBR values significantly and the reduction observed by the use of EPS beads is well-compensated. At $$\eta =0.25\%$$ , the peak strain energy is also enhanced. Active composition (AC), which refers to the minimum value of CaO or the sum of Al2O3 and SiO2 in the mixture, is suggested to render a unique power equation that can readily estimate the UCS and CBR values. It was concluded that the increase of AC and porosity (n) of the mixture, respectively, increases and decreases the strength parameters. Therefore, by the increase of n/AC ratio, the values of strength parameters diminish. Finally, with the aid of the presented power formulas, high-accuracy equations are proposed to correlate the UCS and CBR values of the samples to the key parameter (n/AC).
PubDate: 2021-10-03

• Influence of water content and dry density on pore size distribution and
swelling pressure of two Indian bentonites

Abstract: The swelling pressure of compacted bentonites plays an important role in the design of deep geological repositories. The current study highlighted the influence of compacted specimen dry density and water content on pore size distribution (PSD) and swelling pressure of two Indian bentonites. Constant volume swelling pressure tests were carried out on one divalent bentonite and one monovalent bentonite at three different dry densities such as 1.4, 1.6, and 1.8 Mg/m3 by varying three initial water contents of 8%, 12%, and 16%, respectively. The change in pore size distribution and morphology of the bentonites were investigated using mercury intrusion porosimetry (MIP) and field emission scanning electron microscopy (FESEM). The results indicate that the compacted dry density has significant role on macropore alteration of both bentonites; however, its effect is marginal on micropores. The macropore volume was noted to significantly decrease in monovalent bentonite due to increase in water content from 8 to 16%. The hydration phenomenon in compacted bentonites was found to be strongly dependent on both the clay fabric and the pore diameter. The high macropore volume of monovalent bentonite exhibited collapse behaviour during swelling process and developed a new family of big pores. However, collapse behaviour was not observed in divalent bentonite due to its small pore diameter. At a given dry density, the compacted divalent bentonite predominantly having Ca-Mg montmorillonite and palygorskite possesses a higher swelling pressure than monovalent bentonite, which has Na-montmorillonite as a predominant component. The effect of initial water content was noted to be negligible on swelling pressure of the monovalent bentonite at a lower dry density of 1.4 Mg/m3. On other hand, irrespective of dry density, the swelling pressure of divalent bentonite decreased with an increase in initial water content; however greater percentage reduction was noted at higher dry densities for both bentonites.
PubDate: 2021-10-02

• Correction to: Strength and dilatancy of coral sand in the South China Sea

PubDate: 2021-10-01

• Correction to: Predisposing and triggering factors of large-scale
landslides in Debre Sina area, central Ethiopian highlands

PubDate: 2021-10-01

• Correction to: Effect of multi-cycle freeze–thaw tests on the
physico-mechanical and thermal properties of some highly porous natural
stones

PubDate: 2021-10-01

• Retraction Note: Relationship between water content, shear deformation,
and elastic wave velocity through unsaturated soil slope

PubDate: 2021-10-01

• Aperture measurements and seepage properties of typical single natural
fractures

Abstract: Fractures play an important role in controlling the hydraulic conductivity of rock masses, and the aperture significantly influences the magnitude of fracture seepage. In this study, field measurements and experiments were conducted at a well-exposed granite fracture site in the Beishan area, China. Several types of single natural fractures were selected to remove the weathered surface and expose the fresh fractures. Subsequently, measuring ruler dispersion-tangent middle axis (MRD-TMA) method was developed to measure the fracture aperture and capture fracture geometry. Then, electrical resistivity tomography (ERT) technique was employed to investigate the seepage properties of these fractures. The results reveal that MRD-TMA method achieved good flexibility and accuracy in the current measurement of fracture aperture, and ERT is a useful tool for detecting the seepage properties of fractures in hard rock masses. Combined with field observations, the filling form of fractures can be categorized according to the ERT inversion results, as follows: open-weak filling, open filling, loose filling, and fully cemented-closed form, whose seepage properties decrease as the filling density increases. Generally, the open-weak filling is the main water channel in a fracture network, while the fully cemented-closed type is a water-blocking fracture and typically exhibits a pseudo-fracture with a large surface opening. In summary, the method for obtaining the morphological characteristics of the aperture can provide a low-cost and time-efficient approach for fracture logging in the field, and ERT technique provides a reference for the detection of potential hazards caused by connected water-conducting fractures in rock engineering.
PubDate: 2021-10-01

• Rheological properties of combustion metamorphic rock slurry for coalfield
fire prevention

Abstract: Coal fire disasters seriously threaten the safety of coal mine production and the surrounding ecological environment. Grouting is an important coal fire control method that involves the sealing of underground cracks and isolation of coal-oxygen contacts. This paper proposes the use of combustion metamorphic rock as a new grouting material to replace loess grouting to resolve the scarcity of loess resources. Stability experiments showed that the slurry syneresis rate increased with increasing water-cement ratio and metamorphic rock content. Mixed slurries with a water-cement ratio of 0.45:1 and slurries containing 20 wt.% and 40 wt.% combustion metamorphic rocks with a water-cement ratio of 0.6:1 were determined to be stable. The addition of cement significantly increased the shear stress of the slurry and greatly improved the rheological properties compared to pure rock slurry. When the water-cement ratio was lower than 0.6:1, the viscosity of the mixed slurry increased with increasing combustion metamorphic rock proportion, whereas the opposite trend was observed for higher water-cement ratios. Based on the stability and rheology of the mixed slurries, the optimal composition was determined to have a 0.6:1 water-cement ratio and 40 wt.% combustion metamorphic rock. The results show that the use of combustion metamorphic rock as a grouting material to replace loess is a viable method for mitigating coal fire disasters. This study provides an important reference for the replacement of loess grouting, which serves to ensure the safety and environmental protection of coal fire areas.
PubDate: 2021-10-01

• Dynamic characteristics of Xianyang loess based on microscopic analysis: a
quantitative evaluation

Abstract: In order to achieve a quantitative evaluation of the relationship between microstructure and dynamic characteristics of saturated loess, scanning electron microscope tests were carried out on the undisturbed samples and the samples experienced dynamic triaxial tests which were performed under dynamic loads of different amplitudes, frequencies, waveforms and confining pressures. The dynamic elastic modulus and microstructural parameters of loess under different types of dynamic loads were quantified at different stages of dynamic triaxial testing. The relationship between dynamic elastic modulus and microstructural parameters such as the diameter, average abundance, average fractal dimension and directional probability entropy of the structural units and pores was established through grey relation analysis and multivariate linear regression analysis; then, the global sensitivity analysis method (Morris method) was used to analyse the global sensitivity of each parameter. The result shows that when the waveform, confining pressure and amplitude are different, the dynamic elastic modulus of samples is mainly controlled by the microstructural characteristics of the pores. However, it is mainly controlled by the microstructural characteristics of structural units when the frequency changes. Furthermore, the sensitivity of microstructural parameters of pores is generally higher than that of structural units under different loading conditions.
PubDate: 2021-10-01

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