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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  [2469 journals]
• Particle breakage and shape analysis of calcareous sand under
consolidated-undrained triaxial shear

Abstract: Abstract To investigate the meso-fabric characteristics of calcareous sand (CS) under undrained shear conditions, multiple consolidated-undrained triaxial shear tests were conducted on CS under different effective confining pressures ( $${\sigma }_{3}^{^{\prime}}$$ ), and the particle gradations and shapes of CS before and after triaxial shear tests were measured using screening tests and particle shape scanning tests, respectively. According to the results, (I) the consolidated-undrained triaxial shear tests on CS can be regarded as a process of transforming from weakening frictional strength to reinforcing cohesive strength. (II) The relative breakage ratio (Br) and modified relative breakage index ( $${\text{Br}}^{*}$$ ) of CS both increased in power function form with increasing $${\sigma }_{3}^{^{\prime}}$$ . The Br of CS was less than its $${\text{Br}}^{*}$$ under the same $${\sigma }_{3}^{^{\prime}}$$ . The connection between the Br and plastic work of CS under undrained shear conditions was established. Splitting and abrasion were the main particle breakage patterns of CS during consolidated-undrained triaxial shear. (III) After consolidated-undrained triaxial shear tests, the particle shape of CS became increasingly regular. Due to the diversity of particle breakage patterns, the mean particle shape parameter of CS did not show any monotonic change with increasing $${\sigma }_{3}^{^{\prime}}$$ .
PubDate: 2022-05-12

• Response of landslide deformation to rainfall based on multi-index
monitoring: a case of the Tanjiawan landslide in the Three Gorges
Reservoir

Abstract: Abstract Landslide deformation in the Three Gorges Reservoir Area (TGRA) is mainly caused by water level fluctuations; however, it is also influenced by rainfall. The Tanjiawan landslide is one of the most notable landslides affected by rainfall in the TGRA. This study investigates the landslide’s deformation mechanism by analysing reconnaissance data, which are surface deformation survey data, and GPS displacement data for the last 16 years along with several types of monitoring data from equipment installed in 2020. The landslide has undergone significant deformation since September 2014. Subsequent rainfall events have caused severe deformation, and tension cracks have appeared in many parts of the landslide. Owing to the slope structure and rainfall events, a deformation feature has developed, in which sliding masses no. 1 and no. 2 are the active and secondary deformation zones, respectively. The surface displacement of the landslide is clearly step-like, and its episodic deformation is controlled by rainfall. Landslide deformation leads to the development of cracks in the slope, producing dominant seepage channels. As rainwater enters belowground along the cracks and with the influence of the bedrock morphology, the groundwater level in the middle and rear parts, and hence, the hydrodynamic pressure, increase, thereby activating landslide deformation. Both continuous rainfall and heavy rain are responsible for this phenomenon; sliding mass no. 1 shows an overall downward motion. Finally, the seismic data recorded by microcore piles and the change rate in soil moisture content after rainfalls can currently be used for reliable early warnings of landslide instability.
PubDate: 2022-05-11

• Multimethod geophysical investigation in karst areas: case studies from
Silesia, Poland

Abstract: Abstract Carbonate rocks are particularly susceptible to karstification, resulting in the formation of structures, such as enlarged fissures, caverns, and sinkholes. These structures pose direct risk to construction and human safety, especially in urbanised areas. In this study, we demonstrate the application of multimethod geophysical reconnaissance, combining electrical resistivity tomography (ERT), induced polarisation (ERT-IP), seismic refraction tomography (SRT), and multichannel analysis of surface waves (MASW), to identify the subsurface karst structures at two sites in the Silesian District, Poland. This methodology allowed the identification of the geological structure to a depth of up to 40 m, which exceeds the requirements for geotechnical reconnaissance. At site 1, Niedzieliska, a 30-m-wide and 20-m-deep structure, filled with younger sediments, was interpreted as a karst sinkhole. At site 2, Tucznawa, a 180-m-wide fault zone overlain with suffusion-susceptible sediments was identified. The multimethod geophysical approach presented here can be applied to locate and interpret subsurface karst forms in similar karst terrains worldwide.
PubDate: 2022-05-11

• Probabilistic assessment of effects of heterogeneity on the stability of
coal mine overburden dump slopes through discrete element framework

Abstract: Abstract The proper assessment of stability of overburden (OB) dump slopes for the prevention of unforeseeable incidents has become a crucial issue for the coal mine industries across the globe. Coal mine OB is a highly heterogeneous material varying in shape, size and mineralogical composition. In the present study, Voronoi tessellation scheme is adopted for the simulation of OB dump materials through the programmable discrete element–based software, Universal Distinct Element Code (UDEC). A probabilistic investigation based on the concept of factorial design approach is carried out to consider the uncertainty of heterogeneous material parameters. A prediction model has been framed for the evaluation of factor of safety (FOS) of the coal mine OB dump slope taking into account, the aspect of its heterogeneity. The influence of various material parameters on the stability of the OB dump slope is also investigated. Finally, the probability of failure of the OB dump slope has been evaluated using Monte-Carlo technique.
PubDate: 2022-05-10

• Automatic identification of rock discontinuity sets using modified
agglomerative nesting algorithm

Abstract: Abstract Identification of rock discontinuity sets is essential for each studied jointed rock slope, and is also an initial step in many existing methods for rock slope stability analysis. This paper presents a new hierarchical agglomerative clustering method using modified agglomerative nesting (MAGNES) algorithm for automatically partitioning discontinuity sets. It is an orientation-based clustering method, and different linkage criteria (single, complete, and average) are incorporated for merging two closest clusters. The performance of MAGNES is tested using a complicate artificial data set, Shanley and Mahtab’s data set, and a real data set from unmanned aerial vehicle (UAV) survey. In addition, the clustering results of four other well-recognized clustering methods are also chosen as comparisons. It shows that the single linkage criterion is inapposite for partitioning orientations and the complete linkage criterion is not robust. Only MAGNES using average linkage criterion (MAGNES_AVG) shows good performance for detecting discontinuity sets. Generally, the main discrepancies among the clustering results lie mainly in the poles at the boundary of two adjacent joint sets. Considering the real data sets are characterized by “ground truth,” the artificial data set with known classification labels is used to further test which method performs better. The number of misclassification points is adopted as an evaluation index, and MAGNES_AVG performs best in partitioning the poles at the boundary of adjacent joint sets. Another advantage of the proposed algorithm is that it is independent of initial parameters, which is user-friendly.
PubDate: 2022-05-10

• Study on correlation between ground motion parameters and soil slope
seismic response

Abstract: Abstract The reasonable selection of parameters will be of great significance for earthquake landslide assessment. To study the correlation between the ground motion parameters and slope seismic response, 100 records of actual ground motion with different characteristics were selected, and each of the ground motions’ peak ground acceleration (PGA), peak ground velocity (PGV), peak ground displacement (PGD), effective peak acceleration (EPA), arias intensity (AI), cumulative absolute velocity (CAV), duration, and characteristic period were taken into account. Moreover, a two-dimensional finite element model of soil slope was established; the deformation and stress response of the slope under each ground motion condition were simulated. The influence law of the ground motion parameters on soil slope seismic response has been revealed, with the correlation between the ground motion parameters and the soil slope seismic response being reflected. The results can provide a theoretical basis for selecting the ground motion parameter indexes in the soil slope seismic analysis and the hazard evaluation of earthquake-induced landslide (EQIL).
PubDate: 2022-05-07

• Repeated failure of a high cutting slope induced by excavation and
rainfall: a case study in Fujian, Southeast China

Abstract: Abstract The slide of a cutting high slope has frequently been induced by rainfall during excavation, gradually transforming the small deformation of the slope into a large hazard. It embodies the complexity, diversity of landslide mechanism, difficulty in selection, and optimization and implementation of a control scheme. Based on the case analysis of disaster control for a typical high cutting slope, this paper firstly introduced its engineering geological model, the characteristics of deformation and failure of the repeated sliding, and the corresponding control measures. Second, the repeated deformation characteristic and failure mechanism of the high cutting slope under the condition of excavation and water-level variation were analyzed using the finite element strength reduction method. Finally, the experiences and lessons of landslide control were concluded, such as the forecasting and fixing of failure mode, identification and control of unstable factors, optimization and adjustment of supporting measures, selection and avoidance of construction timing, and management and control of engineering quality. Research indicates that the engineering excavation was a sensitive factor for slope instability, and the groundwater level caused by continuous rainfall simultaneously decreased the stability of the slope, resulting in repeated deformation. Landslide control is a systematic process of engineering risk regulation comprising qualitative judgment, quantitative calculation and dynamic assessment of slope stability, targeted optimization of landslide control schemes, reasonable plan in timing and process of treatment, strict management, and monitoring of engineering quality.
PubDate: 2022-05-07

• Correction to: What causes the excessive metro tunnel settlement in soft
deposits: learned from a detailed case with factor decomposition

PubDate: 2022-05-06

• System reliability analysis of landslides subjected to fluctuation of
reservoir water level: a case study in the Three Gorges Reservoir area,
China

Abstract: Abstract Reservoir-induced landslides are a common type of geological hazards in the hydropower area, where the frequent occurrence of catastrophic landslides has attracted widespread attention. This study focuses on the Huangtupo Riverside Slump 1#, a reservoir-induced landslide in the Three Gorges Reservoir Area of China, which has been investigated with double sliding surfaces. First, a series of numerical analyses are conducted to obtain the seepage field inside the landslide subjected to fluctuation of reservoir water level. Then the stability of the landslide is analyzed by employing the results of the seepage field. Subsequently, considering the uncertainty of strength parameters of sliding surfaces, the failure probabilities for the individual sliding surfaces are assessed via first order reliability method, and then the system reliability of the landslide is analyzed by applying the Ditlevsen’s bounds method. The results indicate that the change of seepage field is closely related to the scheduling of reservoir water level and lags behind the scheduling, which has a greater impact on the stability of the 1–1# failure surface than the 1–2# failure surface. Similarly, the bounds of system failure probability vary with the reservoir water level, and the most dangerous probability occurs when the water drops to the lowest level. Evaluating the landslide from the perspective of system reliability greatly narrows the risk range, which has potential for further application in risk management and control. Besides, the relationships between the correlation coefficient of strength parameters and the landslide system response are discussed through parametric analyses.
PubDate: 2022-05-06

• Influence of water content on the basic friction angle of porous
limestones—experimental study using an automated tilting table

Abstract: Abstract An accurate evaluation of the shear strength of discontinuities is frequently a key aspect for determining the safety of mining and civil engineering works and for solving instability issues at rock mass scale. This is usually done by using empirical shear strength criteria in which the basic friction angle (φb) is a relevant input parameter. Tilt testing is probably the most widespread method to obtain the φb due to its simplicity and low cost, but previous research has demonstrated that the results are strongly affected by several factors (e.g. surface finishing, cutting speed, specimen geometry, wear, time and rock type). In this connection, despite it is well known that water significantly reduces the mechanical properties of sedimentary rocks, very scarce research has focused on assessing the impact of the variations in water content on tilt test results. With the aim to fill this gap, saw-cut slabs of three limestone lithotypes were tilt tested in dry state, wet condition (fully water saturated, non-submerged samples) and under exposure to an environmental relative humidity (RH) of 90%. The results revealed that full water saturation caused moderate φb reductions in two lithotypes and a φb increase in one lithotype. This can be explained by their different microstructure and mineralogy, which makes that lubrication effect prevails over suction effect or vice versa. However, the exposure to a high RH environment did not cause significant φb variations. In addition, some important considerations related to tilt testing are provided and discussed, such as the intrinsic variability of the sliding angle (β) and the impact of multiple sliding on the same rock surfaces on β.
PubDate: 2022-05-05

• Hydraulic properties of ignimbrites: matrix and fracture permeabilities in
two pyroclastic flow deposits from Cimino-Vico volcanoes (Italy)

Abstract: Abstract Hydrological properties of ignimbrites are known in detail only for some areas, although these rocks cover large areas with considerable thicknesses in many volcanic regions of the world. This study investigates hydrological properties of two ignimbrites of Latium (Central Italy), different in age, composition, and origin. The dual porosity of the ignimbrites was examined through laboratory tests, pumping tests, and outcrop surveys. The degree of welding, composition, and stratigraphy of the two ignimbrites are the main factors determining their hydrological properties. The two ignimbrites share a low matrix permeability, showing a different fracturing degree. The more welded ignimbrite is characterized by lower porosity of the matrix and higher fracturing degree, while the less welded ignimbrite is characterized by higher porosity of the matrix and lower fracturing degree. Hydraulic conductivity and storage capacity of the highly welded ignimbrite mainly depend on the denser network of discontinuities. The hydraulic conductivity of the younger ignimbrite, less welded, mainly depend on the sparser network of discontinuities and on the layer of unconsolidated coarse pyroclastic deposits at its base, while the storage capacity depends on the more porous matrix. Should the pyroclastic rocks be used as aquifer for water supplies, or, in other cases, as substratum of waste disposal sites, the dual porosity of the ignimbrites must necessarily include different scales of analysis in order to evaluate the role of matrix and fractures on the permeability of rock mass. In any case, the results of laboratory and on-site tests are to be interpreted taking into account the stratigraphy of the ignimbrite.
PubDate: 2022-05-04

• Comparative study on the deformation moduli of roadway surrounding rock in
coal mines: a case study

Abstract: Abstract Since deformation modulus of rock mass is an important parameter for analyzing the mechanical properties of roadway surrounding rock in coal mines, accurate acquisition of the deformation modulus of roadway surrounding rock is essential for mining design, roadway support, and disaster prevention. To achieve this aim, the roadway surrounding rock in Chahasu Coal Mine was taken as the research case. First, uniaxial compression experiments and true triaxial compression experiments were carried out on coal and rock samples. The laboratory deformation modulus of rock mass was determined by stress–strain curves, and the in situ deformation modulus of rock mass in coring boreholes was obtained with the aid of the GY-75 borehole jack. Meanwhile, based on the results of rock mass quality evaluation, the estimated values of deformation moduli of roadway surrounding rock were obtained through an empirical equation. As displayed through the comparative study on the relations between deformation moduli obtained by different methods, with the increase of rock mass depth, in situ deformation modulus increases gradually with reduced growth amplitudes, and its spatial distribution characteristics can be expressed by an exponential function. For roadway surrounding rocks at the same depth, the relation between in situ deformation modulus and deformation moduli obtained from the uniaxial compression experiment and the true triaxial compression experiment can be given by an exponential function and a linear function, respectively. The empirical equation based on the single index RMR shows strong applicability in estimating the deformation modulus of roadway surrounding rock.
PubDate: 2022-05-04

• A data-driven method for predicting debris-flow runout zones by
integrating multivariate adaptive regression splines and Akaike
information criterion

Abstract: Abstract Debris-flow runout zones are important parameters for delineation of endangered areas and design of mitigation works. It is necessary to properly determine the debris-flow runout for hazard assessment and control measures design. Many empirical-statistical correlations have related runout characteristics (e.g., runout distance) to debris-flow volume or topographical parameters. However, the predictability of empirical-statistical models is always questionable due to the great randomness of debris flows and assumption of inputs and functional relationships prior to analysis. This paper develops a data-driven method to predict the debris-flow runout by integrating multivariate adaptive regression splines (MARS) and Akaike information criterion (AIC) without assumption of input parameters and specific function relationships. The debris-flow volume and topographical parameters (e.g., catchment internal relief) are investigated as candidate inputs to train MARS models for estimating the runout characteristics of debris flows. Then, the most appropriate inputs and MARS models for debris-flow runout are identified by AIC. The proposed approaches are illustrated using channelized debris-flow data in Wenchuan earthquake zone. Results showed that the developed method can select the most appropriate MARS models for the debris-flow runout zones in Wenchuan earthquake-stricken area. The developed MARS models portray the regression relationships entirely "driven" from the training data and provide objective and explicit relationships of debris-flow runout zones. Compared with the previous empirical correlations in Wenchuan area, the proposed MARS models have higher prediction accuracy. Even for extreme debris-flow events, the MARS models also show satisfactory accuracy.
PubDate: 2022-05-04

• Influence of grain size or anisotropy on the correlation between uniaxial
compressive strength and sound velocity

Abstract: Abstract Uniaxial compressive strength (UCS) is a critical rock strength parameter, and sound velocity tests are often employed to estimate UCS. However, the equations relating UCS to the sound velocity are grain size or anisotropy dependent, and how such equations respond to these factors remains unknown. To provide guidance for using the sound velocity to predict the UCS of heterogeneous rocks, sandstone (fine- and coarse-grain) and gneiss (0°, 45°, and 90° inclined anisotropy) samples are used to explore the effect of grain size and anisotropy, respectively, on correlations between UCS and the sound velocity. Several significant formulas for predicting UCS can be developed via the sound velocity, except in the case of gneiss with vertical anisotropy. The coarse-grain size and 45° inclined anisotropy increase the discreteness of the UCS data but not the sound velocity. The varying grain size and anisotropy orientation exert a negative influence on the correlation degree between UCS and the sound velocity. UCS values estimated using fine-grain rocks have the lowest relative errors, while considerable relative errors in the estimated UCS occur when using the sound velocity from samples with multidirectional anisotropy. Using empirical equations while ignoring grain size and anisotropy may therefore yield considerable discrepancies in the estimated UCS. This study suggests that the P-wave velocity is the best choice for predicting UCS. Tests should take into consideration varying grain sizes and be performed on rocks with unidirectional anisotropy; however, tests should not be conducted parallel to the anisotropy because of the lack of significant correlation.
PubDate: 2022-05-03

• Stabilization and improvement soils characteristics using natural and

Abstract: Abstract The purpose of the present research is to study different soil stabilization methods using natural and industrial additives. soil samples were collected from three areas in southwestern of Iran (Khorramshahr, Chooebdeh port of Abadan and Imam Khomeini port (Mahshahr) using scanning electron microscopy (SEM), X-ray diffraction (XRD) mineralogical, and laser particle size analyzer (LPSA) method to monitor samples’ physicochemical and granulation. The additives were Portland cement type II (with 5% and 8% composition by volume), hydrated lime (with 5% and 7% volumetric composition), propylene fibers (with a combination of 0.5% and 1% by weight), and micro silica powder (with 5% and 8% volumetric composition). The research findings indicated relatively similar distribution of soil particles, despite the relative differences in geo-environmental conditions and a high abundance of clay and silt particles. The results also showed that increasing the additives to the original samples will multiply the parameters of plasticity index, consolidation of dry density, adhesion coefficient, internal friction angle, and the compressive strength for all samples. Moreover, It is demonstrated that of the additives used at all three understudied regions, cement with 8% composition by volume on the plasticity index (8.55% increase), micro silica powder with 8% volumetric composition on consolidation of dry density in Khorramshahr (4% increase), propylene fibers with a combination of 0.5% on the adhesion coefficient (0.44% increase), cement with 8% composition by volume on internal friction angle, and propylene fibers with a combination of 1% had much greater effects on compressive strength. According to the research results, it is recommended to use propylene fibers with a combination of 0.5% or micro silica powder with 8% volumetric composition to soil improvement.
PubDate: 2022-05-03

• IoT-based hydrological monitoring of water-induced landslides: a case
study in central Norway

Abstract: Abstract Water-induced landslides pose a great risk to the society in Norway due to their high frequency and capacity to evolve in destructive debris flows. Hydrological monitoring is a widely employed method to understand the initiation mechanism of water-induced landslides under various climate conditions. Hydrological monitoring systems can provide relevant information that can be utilized in landslide early warning systems to mitigate the risk by issuing early warnings. These monitoring systems can be significantly enhanced, and wider deployments can be achieved through the recent developments within the domain of the Internet of Things (IoT). Therefore, this study aims to demonstrate a case study on an automated hydrological monitoring system supported by the IoT-based state-of-the-art technologies employing public mobile networks. Volumetric water content (VWC) sensors, suction sensors, and piezometers were used in the hydrological monitoring system to monitor the hydrological activities. The monitoring system was deployed in a case study area in central Norway at two locations of high susceptible geological units. During monitored period, the IoT-based hydrological monitoring system provided novel and valuable insights into the hydrological response of slopes to seasonally cold climates in terms of VWC and matric suction. The effects of rainfall, snow melting, ground freezing, and thawing were captured. The current study also made an attempt to integrate the collected data into a physical-based landslide susceptibility model to obtain a more consistent and reliable hazard assessment.
PubDate: 2022-05-02

• Investigating deformation patterns of a mining-induced landslide using
multisource remote sensing: The songmugou landslide in Shanxi Province,
China

Abstract: Abstract Landslides induced by mining always cause serious economic losses and human deaths in mining areas. The nature of these disasters argues for a reverse analysis of slope monitoring data to assess the cause, size, and temporal evolution and to further predict the potential risks of future disasters. In this paper, we investigated the Songmugou Landslide based on multisource remote sensing techniques. More specifically, we first investigated the geomorphological features and the time series subsidence rates across this slope from December 7, 2015 to April 26, 2019, by exploiting unmanned aerial vehicle (UAV) and small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) monitoring, we then analyzed the deformation characteristics, active zonation, and secondary landslide risk of the study area by integrating geological, engineering, and rainfall data. Finally, we discussed reasonable evolution sequence and potential risk of the landslide and provided several suggestions for subsequent geological hazard prevention. The results indicate that this comprehensive approach can be used to back-analyze and reasonably predict the evolutionary mechanism of landslides.
PubDate: 2022-05-02

• Kinematic limit analysis of the slope encapsulating a laterally loaded
pile

Abstract: Abstract This study aims to present a theoretical method for the safety factor of a slope encapsulating a laterally loaded pile. The factor can be derived by the object function concerning the external work rate and internal energy dissipation based on kinematic limit analysis, after assuming the log-spiral failure mechanism of the slope. To address the core issues (the critical point depth and lateral force provided by the pile) in the analysis, the modified strain wedge technique and the soil wedge assumption were adopted to evaluate the soil resistance and extra earth pressure around the pile, respectively. Besides, the proposed method was verified by published data and numerical methods, and the slope failure mechanism was revealed by observing two wedge-shaped failure regions around the pile. Furthermore, the variations of normalized safety factors with normalized lateral loads can be empirically fitted by cubic functions, and the normalized safety factor mainly depends on the lateral load and pile location but is not sensitive to the shear strength. The safety factor of the slope encapsulating a laterally loaded pile (FoS1) can be thus alternatively predicted by scaling the safety factor of the slope without the lateral load (FoS0) with the corresponding normalized safety factor η.
PubDate: 2022-04-29

• The effect of metamorphism on the aggregate properties of gabbroic rocks

Abstract: Abstract Granitic rocks are durable materials sought after for the production of road and railroad aggregates. Granitic bedrock commonly, however, includes gabbroic components, which may enhance or decrease the aggregate performance. This study evaluates the variation in resistance to fragmentation (Los Angeles value, LA) and wear/abrasion (micro-Deval value, MDE) for the fraction 10/14 mm of gabbro in different metamorphic states. Samples were collected along a 150-km profile where metamorphic conditions grade from epidote–amphibolite to high-pressure granulite-facies, and the degree of metamorphic recrystallization varies with the amount of hydrous fluid. Rocks with no or incipient metamorphic recrystallization preserving their primary igneous fabric and interlocking texture meet the criteria for both asphalt base course and track ballast in railroad, with LA and MDE values below 25% and 14%, respectively. Mafic granulite and fine-grained amphibolite have LA values below 25% and can be used in unbound layers. Mafic granulites crystallize at high temperatures but commonly preserve a relict igneous texture due to limited hydration. Coarse-grained amphibolite and migmatitic amphibolite have the poorest performance. They recrystallized at hydrous conditions, leading to complete recrystallization, grain coarsening, and loss of interlocking igneous texture. This study shows that both temperature and infiltration of hydrous fluids significantly affect the technical properties. Even at high metamorphic temperatures, gabbroic rocks may yield aggregates of high technical performance. At hydrous conditions, however, recrystallization results in rock aggregates suitable for unbound layers only. The variation in metamorphic grade and hydration is easily assessed by the geologist in the field and by using standard petrographic microscopy.
PubDate: 2022-04-28

• Determination of rock quality designation (RQD) in metamorphic rocks: a
case study (Bayburt-Kırklartepe Dam)

Abstract: Abstract The role and importance of rock mass classification systems from past to present in engineering designs are indisputable. Therefore, the correct estimation of the parameters that make up these systems is essential in terms of reliability, time, and economy. One of the crucial parameters commonly used in rock mass classification is the rock quality designation (RQD). This study aimed to indirectly estimate the RQD value determined from the core samples obtained from the exploration drillings. In this context, P wave velocity (Vp) was obtained by seismic refraction tomography (SRT) from the geophysical measurements applied in the metamorphic rock mass, and the discontinuity frequency parameter was obtained from the line survey studies carried out on the rock mass. What determined RQD values with the help of simple regression analyzes and empirical equations with high estimation capacity using Vp and discontinuity frequency parameters were obtained without drilling in the rock mass. Accordingly, the performance indexes of the equations produced by different researchers and the equations produced in this study were evaluated in determining the RQD parameter. In the generated equations, the highest coefficient of determination value depending on joint frequency and Vp wave velocity with RQD was calculated as R2 = 0.89 and R2 = 0.82, respectively. When the produced equations are evaluated according to the performance indexes, it is seen that the empirical equations obtained by previous studies have the highest root mean square error (RMSE) and values account for (VAF) values compared to the other equations and have very high estimation capacities. Thanks to the equations with high estimation capacity, the RQD value was determined depending on the joint density and Vp speeds.
PubDate: 2022-04-28

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