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Understanding the interface shear strength is crucial for the design of geotechnical structures. This study investigates the effect of surface roughness on the interface friction angle, peak interface friction coefficient, and interface shear strength through direct interface shear tests. The experiments were performed on 10 samples of concrete and steel with the level of roughness varying and soil. The objective is to provide soil parameters for a site that is located around 6 km away to the south of Al-Amarah city, Southeast of Iraq where earthquakes hit frequently. The research is intended to investigate the effect of earthquakes on objects that are built in that particular region, by putting emphasis on the interaction between the soil structure and the roughness of the contact surface between the structural parts and the soil. In order to evaluate the roughness nature of structural materials, a test program was conducted using the SRT-6210 Digital Surface Roughness Tester. The average roughness parameter (R a) had the strongest association with shear parameters, and so it is the indicator to explain the shear behavior of sand‒concrete and sand‒steel interfaces. The direct shear box test was employed to find out the soil’s shear strength parameters as well as the interface shear strength parameters. The test shows a profound change in the shear strength characteristics of sand‒concrete and sand‒steel indispensable interfaces. As the roughness index increased. It depicted an upward slope of apparent shear strength and friction coefficient taken at the interface. The shear strength had increased by 25.13% when the roughness of the concrete was below 20 μm20{\rm{\mu }}{\rm{m}} and by 36.26% when the roughness of the steel was below 30 μm.\hspace{0.25em}30{\rm{\mu }}{\rm{m}}.\hspace{0.25em} Moreover, sand‒steel samples interface friction angle increased by approximately 31.5% with increasing surface roughness and sand‒concrete samples by 21.54%. The results also revealed that the peak interface friction coefficient (μp)\left(\mu p) increased with the increase in R a.

This study investigates the effect of surface roughness on the interface behavior between clayey soils and structural materials, aiming to determine the necessary parameters for soil-structural interaction. The research site, located in one of Iraq’s seismically active regions, was selected for its significance. Experimental measurements were conducted using the SRT-6210 Digital Surface Roughness Tester to assess the roughness characteristics of steel and concrete samples. Four distinct roughness parameters were measured, and their correlation with shear parameters was analyzed. The shear behavior of clay-steel and clay-concrete interfaces was successfully described using the average roughness parameter (Ra), which exhibited the strongest correlation with shear parameters. Direct shear box and interface shear box tests were employed to identify soil’s shear strength parameters and evaluate interface shear strength parameters. The experimental findings highlight the significant influence of surface roughness on the shear strength parameters of clay-steel and clay-concrete interfaces. The interface shear strength, friction angle, and adhesion exhibited an increasing trend with roughness. Notably, shear strength increased by approximately 29.76% when concrete sample roughness was below 20 μm and by 32.8% when steel sample roughness was below 30 μm. Moreover, increasing surface roughness improved the interface friction angle of clay-steel and clay-concrete samples by about 37.95 and 36.3%, respectively. Additionally, an increase in roughness led to a rise in the adhesion of concrete and steel samples by approximately 26.24 and 32%, respectively. These findings emphasize the significance of surface roughness in optimizing the interface behavior between clayey soils and structural materials. The results have important implications for enhancing the design and performance of soil-structural systems.

The shear strength parameters of loess samples are determined from conventional triaxial shear test results and used in the rational design of sustainable geotechnical infrastructures. However, the rubber membrane that is used in the triaxial shear apparatus for applying the all-around pressure to the test specimen has a significant influence on the measured shear strength parameters. In this paper, remolded and undisturbed unsaturated loess samples from northwest China are used in a comprehensive testing program to determine the shear strength from triaxial tests and understand the influence of a rubber membrane. The results show that the measured undrained cohesion from unconsolidated undrained triaxial tests on unsaturated soil specimens with and without a rubber membrane are significantly different. In this study, differences in the shear strength with and without a rubber membrane are assessed from shear strength index values that can be determined from undrained cohesion and the internal friction angle derived from conventional triaxial tests. Experimental results suggest that predominant changes arise mainly in the undrained cohesion values. The change rate of shear strength indices values of undisturbed loess shows a strong correlation with its water content; however, it is weak for remolded loess. The correlation coefficient between error and measured values of all shear strength indices is more than 0.8. Empirical correction relationships for triaxial shear tests with a rubber membrane for three different types of loess were established from the investigations. The simple approach used in this study can be used as a reference to apply corrections to the measured undrained cohesion values of unsaturated loess samples from northwest China. [ABSTRACT FROM AUTHOR]

The loads generated inside agricultural silos under static and dynamic conditions depend on the mechanical properties of the materials stored inside them. Silo calculation methodologies are based on these mechanical properties. Although it is known that moisture content greatly influences the values reached by these mechanical properties, only a few studies have been conducted to determine them. The present work determines the angle of internal friction, the apparent cohesion, the dilatancy angle and the apparent specific weight of wheat when subjected to different moisture contents. Direct shear and oedometer assay devices were used. In addition, a climatic chamber was used to moisten the wheat samples used in this work. From the different assays conducted, it could be observed that the values of the angle of internal friction, the apparent cohesion and the apparent specific weight were like those found in the literature. However, no values of the dilatancy angle of wheat as influenced by moisture content were previously reported. The values obtained here for this parameter are within the range of those specified for dry wheat samples. Finally, higher apparent specific weight values were observed as moisture content increased up to 13.4%, then decreasing at a moisture content of 15.5%. This was not expected according to the results stated by some authors, although others reported a similar tendency. The values here provided can be used in silo load calculations involving numerical methods for modeling technological processes. [ABSTRACT FROM AUTHOR]

One of the aspects that affect structure stability is the soil--structure interaction. A good example of this interaction can be witnessed in footings, in which the properties of the soil surrounding the structural parts and the structural parts themselves affect the engineering behavior of the interaction between concrete footings and the soil. Contact stress distribution represents such interaction. However, contact stress distribution beneath concrete footings does not solely rely on the soil type and behavior of footing in working limit state, but also on the variation in the concrete footings stiffness after cracking. The main purpose of this research is to investigate the effect of the reduction in the concrete footing stiffness due to cracking on the contact stress distribution beneath concentric isolated footings resting on cohesive soil. In this respect, numerical simulation and validation was carried out using a non-linear finite element program 'Abaqus'. A parametric study was conducted to extend this study by including soil cohesion, internal friction angle, rebars yield strength, and foundation depth as investigated parameters. The concrete foundation behavior and failure mode were analyzed. The findings of this research indicate that the different variations of cracks in reinforced concrete showed different shapes of contact stress distribution. [ABSTRACT FROM AUTHOR]

The current study proposes a novel field Torsional Direct Shear Test (TDST) that can measure the field shear strength of soils with particle sizes up to 12.5 mm. TDST apparatus comprises an open cylinder 300 mm in diameter and 90 mm in height. The cylinder has two vanes fixed at 90° to one another at the center. It also has a 25 mm thick circular cover plate, quarter plates covered by the vanes, and a vertical loading column. Here circular cover plate transfers the normal load applied to the loading column, and the torsional load is applied to the loading column using the lever arm. Quarter plates allow the soil to dilate while shearing, enabling the measurement of shear strength under a known, constant applied normal stress. To validate the performance of the TDST apparatus, set up modified, and used in the laboratory large box direct shear test setup. The results of the laboratory TDST setup were compared with those obtained using the laboratory DST. It was found that the angle of internal friction (ϕ) measured using the proposed TDST was nearly identical to that measured using the laboratory DST. In contrast, the cohesion (c) measured using TDST was about 1.2 times greater than that measured using DST. The proposed in situ TDST method does not require a large horizontal force. Instead, as the length of the lever arm increases, the required force to induce torsional stress in soil reduces, making the method much easier to perform than the conventional field DST. [ABSTRACT FROM AUTHOR]

So far, many studies have been completed on the traditional soil stabilisation using cement or lime, however, very limited literatures pay attention to the mechanical behavior of stabilised soil with new materials. The main objective of the current study was to investigate the mechanical behavior of stabilised soil with polyurethane (PU) foam. For this purpose, a series of direct shear tests were performed on soil specimens which were stabilised by PU foam. The study revealed that adding PU foam to sand resulted in a remarkable increase in the shear strength parameters (c and ϕ), which the increase of cohesion was more pronounced than the increase of angle of internal friction. The strength of PU foam-stabilised specimens increased gradually as the PU foam content increased from 0 to 10% and then decreased for additional PU foam content. The interaction between the sand particles and PU foam was investigated by optical micrograph analysis. Finally, a new model was developed to predict the shear strength of PU foam-stabilised specimens. Results indicated a satisfactory performance of the proposed model where the Pearson correlation coefficient was 0.94. [ABSTRACT FROM AUTHOR]

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The strength properties of subsiding loess soils are considered in the mathematical modeling of their compaction by deep explosions. Soil compaction is carried out in order to eliminate their subsidence properties. Correlation and regression analyzes of the dependences of strength on the physical characteristics of loess were carried out, using the soils of the North Caucasus as an example. The correlation dependence of the specific cohesion and the angle of internal friction on the physical characteristics of the subsidence soil is established. Correlation coefficients were obtained for various indices of moisture content and loess density. The studies were carried out before and after soil compaction in this way. Both positive and negative correlations between the studied characteristics of subsiding loess soil were recorded. With an increase in moisture, a high correlation was observed with the strength characteristics of the soil before and after its compaction by deep explosions. The equations of regression of specific cohesion and the angle of internal friction on soil moisture and density are constructed. The reliability coefficients of approximation of theoretical regression equations and experimental data demonstrate high values. The regression equations of specific adhesion and the angle of internal friction on soil moisture showed that the values of strength characteristics increase with decreasing values of soil moisture. The regression dependence of the specific cohesion and the angle of internal friction on the density of subsidence loess has been studied. It has been established that an increase in the values of strength characteristics was recorded with an increase in the density of loess soil before and after its compaction by deep explosions. The constructed regression equations make it possible to predict the strength characteristics of loess at the stage of designing the bases and foundations of construction objects.

Experimental data on the relationship of the residual shear strength of rocks in closed cracks with the functional characteristics of intact rocks – the tensile and compressive components of adhesion, the roughness of the crack surfaces, and the level of normal stresses are presented. A unified integrated approach determines the shear strength of intact and destroyed rocks, the residual shear strength of closed rough cracks has been developed. The approach provides for the selection of stress intervals corresponding to different types of fracture, for each of which a strength criterion is proposed, expressed in terms of functional characteristics of intact rock. An express method for estimating the residual shear strength of rocks by cracks with a rough surface has been developed, in which an improved method of loading samples with spherical indentors is used as a basic test method. The express method implements the transition from the data of mechanical tests of samples with spherical indentors to the shear strength indicators for cracks in the rock mass, taking into account the level of normal stresses and the roughness of the crack surfaces measured in field conditions. In this case the roughness scale developed by Barton is used. The express method is informative and available in the fieldwork.

Industrial processes are the main generator of littering agents, and the growing environmental awareness has contributed to a focus on the issue of littering. One of the biggest environmental issues in the world is how to manage this waste given the limited space available, the high cost of remediation, and the need for landfilling. However, the idea of reusing some of this waste is an alternative solution to decreasing the process of landfilling, and reducing the increase of waste. In this research, three different waste materials were used, namely plastic waste, aluminum waste, and silica sand. Each of these materials was mixed in a ratio of 1, 3, and 5%, with silty sand soil. The consistency limits of maximum dry density and the optimal ratio for the preferred materials were determined by examining and comparing cohesiveness and angle of internal friction. Research results showed that the maximum unit weight decreased after adding the waste materials: it decreased by 9.35 and 11.69% when 5% each of aluminum and plastic waste was added, respectively. At the same time, the increase in the inner angle of internal friction reached 26.41% at the highest percentage of plastic waste. The addition of 3% of silica sand gave the highest value of cohesion, and the increase reached 218.7% for soils not treated with silica. It also showed the effect of adding 1% of silica sand on the plasticity, reducing it by 72.7% from its original value.

Geosynthetics play a pivotal role in modern infrastructure projects, with geogrids serving as a common choice for enhancing bearing capacity and reducing soil settlement in road construction. This study investigates the influence of density and uniformity coefficients on geogrid-reinforced sandy and gravelly soils through a series of consolidated drained triaxial tests. The research covers six distinct soil types from Lithuania, each characterized by particle size distribution analysis and classified using various standards. A polyester biaxial geogrid is employed, and test specimens are prepared with and without geogrid reinforcement. Triaxial compression tests are performed at different cell pressures, mirroring real-world conditions in road construction. The results highlight the critical role of cell pressure in the reinforcement effect, with higher pressures reducing the geogrid's influence. The study also emphasizes the importance of soil type, as gravel soils consistently exhibit higher deviatoric stress than sandy soils. Notably, the geogrid enhances cohesion but reduces the angle of internal friction in most cases. Overall, this research provides valuable insights into the intricate interplay between soil properties, geogrid reinforcement, and cell pressure, shedding light on the mechanical behavior of geosynthetic-reinforced soils in road construction applications. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of unfrozen water content on the strength characteristics of unsaturated seasonal frozen soils, an experimental study was conducted on the strength characteristics of soil samples with different initial matrix suction under different temperature conditions, considering the variation of unfrozen water content, using an unsaturated powdered clay soil in a typical seasonal frozen zone as the research object, using the NMR test system and the GDS unsaturated soil triaxial test system. The results show that the unfrozen water content decreases with decreasing temperature under the same initial matrix suction condition, and decreases with increasing matrix suction under the same temperature condition. The change of volumetric unfrozen water content of unsaturated permafrost during freezing can be divided into subcooling stage (0°C~-1°C), rapid freezing stage (-1°C~-7°C), and stable freezing stage (-7°C~-17°C). As the temperature decreases, the total cohesion of soil samples increases in a refractive line as the unfrozen water content decreases. At temperatures above -5°C, matrix suction increases and total cohesion increases as unfrozen water content decreases; The total cohesion decreases with the decrease of unfrozen water content when the temperature is -10Ԩ or below. As the temperature decreases, the effective internal friction angle shows an overall decreasing trend with unfrozen water content: Under the conditions of 57kPa, 300kPa and 400kPa of matrix suction, the effective internal friction angle of soil sample decreases and then increases with the decrease of unfrozen water content; under the conditions of 100kPa and 200kPa of matrix suction, it will show a gradual decreasing trend with the decrease of unfrozen water content. At a certain temperature, the effective internal friction angle of soil sample decreases and then increases with the decrease of unfrozen water content. [ABSTRACT FROM AUTHOR]

Conventional asphalt pavement is the dominant mode of passenger and freight traffic in Pakistan. As a result, asphalt pavements suffer from various failures, where rutting, corrugation, and fatigue cracking are significant. Fine aggregates and mineral fillers play a pivotal role in providing structural integrity in asphalt pavements when subjected to traffic and the environment. The current study aims to examine the effects of various locally accessible fine aggregate and mineral filler materials on the interlocking properties of asphalt mixtures in relation to internal friction angle, rutting resistance, and controlling environmental pollution as an indirect benefit, thereby reducing wastes. Four distinct asphalt samples were prepared using cinders, stone dust, natural sand, and surkhi as fine aggregates and mineral fillers, as a full replacement, as per ASTM D1559, confirming the Asphalt Institute's gradation for asphalt wearing course. Optimum binder contents (OBC) of 4.40%, 4.1%, 6.57%, and 6.63% by weight of Marshall specimen were concluded for asphalt samples containing stone dust, natural sand, cinder, and surkhi, respectively. The results revealed that surkhi, natural sand, stone dust, and cinder all showed a diminishing tendency in developing interlocking properties in asphalt mixtures at internal friction angles of 35°, 33.7°, 32°, and 28.4°, respectively. The wheel tracking test results revealed that the asphalt samples made with surkhi as fine aggregates and fillers have the highest rut resistance, whereas samples made with cinders as fine aggregates and fillers have the lowest rut resistance. The direct shear test showed that fine aggregates with a larger angle of internal friction are significantly more stable in terms of rut resistance than fine aggregates with a smaller angle of internal friction. The current research will help to prevent pavement rutting and corrugation by adding surkhi into asphalt pavements, with the reduction in brick kiln waste providing an indirect benefit. [ABSTRACT FROM AUTHOR]

The soil properties are studied in mechanics, that is, the important properties according to which the soil can be classified. Based on mechanics, the information is being obtained on how the tested soil can be used. For example: which soil is favorable for the construction of various types of structures, which soil is favorable for the construction of embankments, etc. There are several ways to determine the elements of internal soil resistance, cohesion and angle of internal friction, using the laboratory tests, among which the most famous are the direct shear test, triaxial compression test and uniaxial compressive strength test. This paper will describe the "CU" triaxial test results.

The nature and manner in which structures are collapsing in Nigeria are alarming. It creates a room in which structural engineers, the building industry, government, estate developers, building consultants and other relevant stakeholders in the department building industry ask many questions about how and what is behind the sudden collapse of structures. Therefore, this research aimed to predict the ultimate bearing capacity of the square, strip and circular footing from shearing strength parameters using ANN and ANFIS. This paper, 200 data sets were used to develop the model; 75% were used for training and 25% for testing the model. ANN and ANFIS learning algorithms were employed in developing the models under various foundation types. Eventually, Various error measures, such as coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), and correlation coefficient (R), were employed to compare the efficiency of the models. The performance comparison findings indicated that the soft-computing system is an efficient instrument for risk reduction in soil engineering projects. The models were validated using external data and the correlation prediction capacity of the models where ANN-STRIP (89%), ANN-SQUARE (83%), ANN-CIRCULAR (89%), ANFIS-STRIP (86%), ANFIS-SQUARE (79%) and ANFIS-CIRCULAR (96%). All the models have shown a quite good and reliable prediction capacity, with ANFIS-CIRCULAR having 96% prediction accuracy of soil bearing capacity.

The loads generated inside agricultural silos under static and dynamic conditions depend on the mechanical properties of the materials stored inside them. Silo calculation methodologies are based on these mechanical properties. Although it is known that moisture content greatly influences the values reached by these mechanical properties, only a few studies have been conducted to determine them. The present work determines the angle of internal friction, the apparent cohesion, the dilatancy angle and the apparent specific weight of wheat when subjected to different moisture contents. Direct shear and oedometer assay devices were used. In addition, a climatic chamber was used to moisten the wheat samples used in this work. From the different assays conducted, it could be observed that the values of the angle of internal friction, the apparent cohesion and the apparent specific weight were like those found in the literature. However, no values of the dilatancy angle of wheat as influenced by moisture content were previously reported. The values obtained here for this parameter are within the range of those specified for dry wheat samples. Finally, higher apparent specific weight values were observed as moisture content increased up to 13.4%, then decreasing at a moisture content of 15.5%. This was not expected according to the results stated by some authors, although others reported a similar tendency. The values here provided can be used in silo load calculations involving numerical methods for modeling technological processes.

This study is aimed at determining the intermediate strength characteristics of soil at a given depth between boreholes using geoinformation systems. Changes in the strength characteristics of soils under the influence of load are studied, which is important for assessing the bearing capacity of the foundation and developing optimal solutions for its improvement and strengthening. A comparative analysis of Kriging and IDW methods in ArcGIS software package for determining the spatial variation of soil strength characteristics (c, φ) was carried out. The results showed differences in the values of specific cohesion and angle of internal friction varying depending on the chosen interpolation method. The proposed methodology for determining the intermediate soil strength characteristics takes into account the soil overlay, the thickness of the layers and the relative position of the known values obtained from the monolith selection. This is important for accurate determination of the bearing capacity of the foundation.

The relevance of the study is caused by the activation of landslide processes as a result of human engineering activities, leading to the destruction of infrastructure facilities for the life support of cities and settlements in the Sakhalin Region, as exemplified by a landslide in the area of ​​the clean water reservoir in the village of Sinegorsk in July 2017. At present, the Sakhalin Region is intensively developing the slopes of mountain spurs and sections of the foothills adjacent directly to the slopes. For example, the development of the «Mountain Air» sports complex and the construction of ski slopes cover the slopes that are part of the territory of the city of Yuzhno-Sakhalinsk, and, accordingly, are in close proximity not only to infrastructure facilities, but also to residential areas of the city. Other slopes with built tracks descend into river valleys with equipped reservoirs (the Rogatka and Elanka rivers). The development of unfavorable processes in the form of landslides in these areas can lead to the formation of debris flows of catastrophic proportions, directed also to the districts of the city. Purpose: to study the conditions for the formation of a landslide, evaluate its parameters, identify the reasons for the descent and give a forecast for the development of similar catastrophic processes in the future. Object: reservoir of clean water in the village of Sinegorsk, southern slope. Methods: route reconnaissance surveys, drilling of wells up to 10 m deep with sampling every 0,3 ... 0,5 m, geophysical studies by an OKO-2 GPR installation, laboratory tests of the physical and mechanical properties of soils. Results. According to the research data, the study of the engineering-geological structure of the landslide development site in the clean water reservoir area was carried out. The parameters of the descended landslide were studied, the conditions and reasons for its formation were revealed. A retrospective assessment of the stability of the slope before the descent of a landslide and assessment of the possible development of dangerous geological processes in the studied area in the future are given.

This study represents the angle of internal friction ( ϕ) estimation of silty sand (SM) of Bangladesh using SPT-N, the depth of sample collection, and the grain size analysis results using machine learning models. To develop the predictive model, Multiple Linear Regression (MLR), Support Vector Regression (SVR) and Artificial Neural Network (ANN) algorithms are used. Soil samples have been collected from 210 boreholes beside the rail track of the Joydevpur-Mymensingh-Jamalpur section. The performance of the models is evaluated using the R2 score, Root Mean Squared Error (RMSE) and Mean Squared Error (MAE). According to the evaluation metrics, SVR with Radial Basis Function (Rbf) kernel performs better than ANN and MLR, and a web application is prepared providing estimated ϕ based on the user input. Later SVR is compared with the established empirical equations and shows that Wolff's model is under-predicting and Nitish Puri's model is over-predicting than actual ϕ. However, the model proposed in this study produces lower residual internal friction angle and improved R2 score, RMSE and MAE which can be used to predict the internal friction angle of silty sand in Bangladesh with higher precision. [ABSTRACT FROM AUTHOR]

This work investigates the impact of changes in the moisture content of bulk materials. The regularity of moisture change in bulk materials was evaluated for three different particle size classes of clay powders. The research measures the angle of internal friction and flowability under four different normal loads, reflecting the varying pressures during bulk material storage. The influence of moisture change in bulk materials was most pronounced for the smallest particle size fraction, where even a very small moisture change in the order of tenths of a percent steeply affected flowability due to internal friction. After increasing the moisture content by a few percent, a steady state of flow occurred. Critical value was determined when water in the bulk material caused liquefaction. For larger particle size fractions, the impact of moisture change was evident only at higher values (12.5%), with no liquefaction occurring even at 30% moisture. The change in normal load, on the other hand, affected particles of larger size fractions, resulting in improved flow properties. [Display omitted] • The fine clay fraction 0–0.5 mm is extremely sensitive to changes in moisture • The change in fine clay moisture content showed an AIFE variance of up to 20° • The liquefaction and effect on clay internal friction and flowability were determined • Internal friction of fine clay is explained using regression model • As clay powders moisture increases the effect of normal load on AIFE [ABSTRACT FROM AUTHOR]

Geosynthetics play a pivotal role in modern infrastructure projects, with geogrids serving as a common choice for enhancing bearing capacity and reducing soil settlement in road construction. This study investigates the influence of density and uniformity coefficients on geogrid-reinforced sandy and gravelly soils through a series of consolidated drained triaxial tests. The research covers six distinct soil types from Lithuania, each characterized by particle size distribution analysis and classified using various standards. A polyester biaxial geogrid is employed, and test specimens are prepared with and without geogrid reinforcement. Triaxial compression tests are performed at different cell pressures, mirroring real-world conditions in road construction. The results highlight the critical role of cell pressure in the reinforcement effect, with higher pressures reducing the geogrid’s influence. The study also emphasizes the importance of soil type, as gravel soils consistently exhibit higher deviatoric stress than sandy soils. Notably, the geogrid enhances cohesion but reduces the angle of internal friction in most cases. Overall, this research provides valuable insights into the intricate interplay between soil properties, geogrid reinforcement, and cell pressure, shedding light on the mechanical behavior of geosynthetic-reinforced soils in road construction applications.

Abstract Electrical Resistivity Tomography (ERT) technique has been widely used conventionally to monitor slope instability; however, a detailed study to validate ERT models with geotechnical properties for monitoring of slope instability is still rare. The objective of this work was to evaluate soil water conditions in gravelly sand soil that influences slope instability. The ERT investigation was conducted on a 60 m survey length with 1.5 m electrodes space to obtain subsurface geological structures and geotechnical laboratory tests, and experiments were carried out to obtain soil engineering properties for validation of the ERT model results. Our results revealed three geological zones namely: saturated, weathered granite, boulders and floaters, and resistivity values of 1–800 Ωm, 1,200–4,000 Ωm, and >4,000 Ωm, respectively. The saturated zones were characterized by subsidence during dry season and possible collapsed structures of boulders and floaters during prolonged heavy rainfall. The analyzed ERT models revealed that the slip surface of a potential landslide may occur at the boundary between the saturated and weathered granite zones within 3.0 m depth. The analyzed geotechnical properties also confirmed the ERT result because the potential landslide sliding surface was delineated within 3.0 m depth at the boundary between gravelly sand with a lowest angle of internal friction of 30° and a cohesion of 8 KPa, which was easier to destroy, and silty sand with a high angle of internal friction of 33.8° and a cohesion of 12.7 KPa, which was more difficult to destroy. These findings are very fundamental in shaping the earth's surface, especially in the formation of landscapes.

The safe and sustainable design of rock slopes, open-pit mines, tunnels, foundations, and underground excavations requires appropriate and reliable estimation of rock strength and deformation characteristics. Cohesion () and angle of internal friction () are the two key parameters widely used to characterize the shear strength of materials. Thus, the prediction of these parameters is essential to evaluate the deformation and stability of any rock formation. In this study, four advanced machine learning (ML)-based intelligent prediction models, namely Lasso regression (LR), ridge regression (RR), decision tree (DT), and support vector machine (SVM), were developed to predict in (MPa) and in (°), with P-wave velocity in (m/s), density in (gm/cc), UCS in (MPa), and tensile strength in (MPa) as input parameters. The actual dataset having 199 data points with no missing data was allocated identically for each model with 70% for training and 30% for testing purposes. To enhance the performance of the developed models, an iterative 5-fold cross-validation method was used. The coefficient of determination (R2), mean absolute error (MAE), mean square error (MSE), root mean square error (RMSE), and a10-index were used as performance metrics to evaluate the optimal prediction model. The results revealed the SVM to be a more efficient model in predicting (R2 = 0.977) and (R2 = 0.916) than LR (: R2 = 0.928 and : R2 = 0.606), RR (: R2 = 0.961 and : R2 = 0.822), and DT (: R2 = 0.934 and : R2 = 0.607) on the testing data. Furthermore, to check the level of accuracy of the SVM model, a sensitivity analysis was performed on the testing data. The results showed that UCS and tensile strength were the most influential parameters in predicting and. The findings of this study contribute to long-term stability and deformation evaluation of rock masses in surface and subsurface rock excavations. [ABSTRACT FROM AUTHOR]

Introduction. Checking the soil of the subgrade and the layers of road pavement made of loosely cohesive materials by shear resistance is one of the three mandatory conditions for calculating road clothing according to strength criteria. The methodology for checking the soil of the subgrade and the sandy layers of the road pavement is constantly being modified, which is why changes concerning certain calculation details appear in each new version of the regulatory document. The purpose of this work is to analyze the advantages of the classical solution of A.M. Krivissky and to reveal the essence of the errors made in subsequent modifications of this calculation.Materials and methods. The analysis of solutions is carried out from the standpoint of compliance with the basics of mechanics. It is shown that the calculation of the total shear stress in the classical solution of A.M. Krivissky is performed in accordance with the principle of force superposition, which consists in calculating the components of the stress tensor from each force (time load and the own weight of the layer materials) separately, followed by summing the corresponding components. In this case, the active shear stresses from the temporary load and the own weight of the materials are calculated as the equivalent stress of the Mohr-Coulomb criterion. The calculation of these two components of the total shear stress is performed at the same value of the internal friction angle. Since the angle of inclination of the sliding surface to the main axes is determined by the sum or difference of 45 degrees and half of the internal friction angle, the tangential and normal stresses, which are components of the active shear stress, both from the temporary load and the own weight of the materials, are determined for the same shear surface rotated to the main axes at the same angle. In the current normative calculations, the active shear stresses from the temporary load and the own weight of the materials are determined at different angles of internal friction. This means that the active shear stresses from the temporary load and the own weight of the materials act on two different shear surface rotated to the main axes at different angles. Such stresses cannot be summed up or compared with each other. In addition to this error of the normative calculation methods, their other disadvantages are given.Results. As a result of a detailed analysis of the known modifications of the classical solution, obvious contradictions to the principles of continuum mechanics are established. As an alternative to modern calculation criteria for shear resistance, the article presents criteria for soil strength in which the shear stress exceeds the equivalent stress in the Mohr-Coulomb criterion. The principle of deducing formulas for calculating the first critical load and the total shear stress from the strength criteria under consideration is shown.Conclusion. Conclusions are drawn about the need to return to the classical solution obtained by specialists of the Leningrad School of the USSR, or to develop a fundamentally new solution based on a new plasticity condition in which the total shear stress exceeds the similar characteristic of the stress state of the original Mohr - Coulomb criterion.

The article describes the possibility of using the granulometric analysis of rock cuttings formed in controlled core scratching tests to estimate the angle of internal friction.The study object is the Kovykta gas-condensate field (GCF) that occupies a wide area in the southeastern part of the Irkutsk amphitheater of the Siberian platform. This uniquely complex geological structure holds significant reserves of hydrocarbons. Its sedimentary cover is composed of the Vendian – lower Paleozoic and partly Riphean formations. Their total thickness exceeds 6000 m, as estimated from the new seismic survey data [Vakhromeev et al., 2019].The sedimentary cover of the Kovykta GCF has been studied by surface and borehole geophysical techniques, remote sensing and geostructural methods, in combination with the tectonophysical approach [Seminsky et al., 2018] based on drilling data, including standard and special core sampling data.

Purpose: Application of deep neural networks (DNN) and ensemble of ANN with bagging for estimating of factor of safety (FOS) of soil stability with a comparative performance analysis done for all techniques. Design/methodology/approach: 1000 cases with different geotechnical and similar Geometrical properties were collected and analysed using the Limit Equilibrium based Morgenstern-Price Method with input variables as the strength parameters of the soil layers, i.e., Su (Upper Clay), Su (Lower Clay), Su (Peat), angle of internal friction (f), Su (Embankment) with the factor of safety (FOS) as output. The evaluation and comparison of the performance of predicted models with cross-validation having ten folds were made based on correlationcoefficient (CC), Nash-Sutcliffe-model efficiency-coefficient (NSE), root-mean-square-error (RMSE), mean-absolute-error (MAE) and scattering-index (S.I.). Sensitivity analysis was conducted for the effects of input variables on FOS of soil stability based on their importance. Findings: The results showed that these techniques have great capability and reflect that the proposed model by DNN can enhance performance of the model, surpassing ensemble in prediction. The Sensitivity analysis outcome demonstrated that Su (Lower Clay) significantly affected the factor of safety (FOS), trailed by Su (Peat). Research limitations/implications: This paper sets sight on use of deep neural network (DNN) and ensemble of ANN with bagging for estimating of factor of safety (FOS) of soil stability. The current approach helps to understand the tangled relationship of various inputs to estimate the factor of safety of soil stability using DNN and ensemble of ANN with bagging. Practical implications: A dependable prediction tool is provided, which suggests that model can help scientists and engineers optimise FOS of soil stability. -Originality/value: Recently, DNN and ensemble of ANN with bagging have been used in various civil engineering problems as reported by several studies and has also been observed to be outperforming the current prevalent modelling techniques. DNN can signify extremely changing and intricate high-dimensional functions in correlation to conventional neural networks. But on a detailed literature review, the application of these techniques to estimate factor of safety of soil stability has not been observed. [ABSTRACT FROM AUTHOR]

Purpose. The behavior of slope instability is influenced by many factors, both internal, such as the physical-mechanical properties of materials, and external, such as rain and seismic activity. Sensitivity analysis is used to determine the parameters that have the greatest impact on the level of slope stability. Methods. Sensitivity analysis of embankment slopes uses the coefficient of variation (CV) approach with input parameters namely cohesion and internal friction angle. Findings. The results of the study confirm that the internal friction angle is the most influential parameter on the embankment slope stability. The evidence is that at the highest percentage of CV, there is the highest probability of avalanches, based on these parameters. Originality. In this research, the coefficient of variation method is used to determine which parameters have heterogeneous data distribution and the greatest probability of failure, as well as to test mechanical sensitivity with the concept of changing the percentage of parameters to a safety factor value to validate calculations using the coefficient of variation approach. Practical implications. The sensitivity analysis results are not only limited to values, since the more important is finding out the cause of the influence of these parameters according to field conditions. The reason why the internal friction angle is the most sensitive parameter is the grain size approach, when the limestone mixture in the field has coarse and large grain sizes. Therefore, the surface tends to form rough waves and causes the relatively large grained rocks to have large internal friction angles. [ABSTRACT FROM AUTHOR]

This paper describes an investigation of sandy soil reinforced with vetiver (Vetiver zizanoides) root. Vetiver roots were chosen because of root morphology and root system. Consolidated drained (CD) triaxial compression tests were done on thirty reconstituted samples, mostly of sand-root matrix, where the emphasis was given to prepare the samples more-or-less for a fixed moisture content and density. Among these, three samples were prepared using clean sand for comparison and others were prepared reinforced with vetiver roots. In case of sand-root matrix, root length (RL) and root content (RC), defined as the percent weight of root on total sample weight, were varied in the range 2.54 ~ 6.4 cm and 1.0 ~ 3.5%, respectively. Shear strength parameters were determined from CD triaxial shear tests in the form of apparent cohesion c and angle of internal friction ϕ. The test result shows that the inclusion of root increases the overall strength of soil while decreasing ϕ (compared to the value bared sand) and increasing c, which was zero for bared soil. The increase of c was substantial and in the range of 18–64 kPa. It appeared that for each RC, there exists an optimum RL for which apparent cohesion, and hence overall strength was maximum. [ABSTRACT FROM AUTHOR]

This study focuses on utilizing cone penetrometer models to determine strength (resistance) of sandy soil and also assessment how the relative density and the angle of friction effects on the measured cone penetration resistance in sandy soil. Simple empirical equations are used also to determine the cone penetration resistance components such as the sleeve resistance and the tip resistance. Simple comparison is performed between the measured and calculated soil strength and well agreement is noticed between them.

Crushed soft rocks are becoming inevitable geotechnical materials for construction of foundations, fill material for transportation infrastructures, and earthen dams for economic and environmental reasons. The contemporary issue is to predict the water-induced disintegration of these non-traditional granular materials and its correlation with the friction angle of these soils. Machine learning techniques offer a viable solution in this context as they are widely used to understand and predict complex phenomena across various applications. In this work, a deep learning technique, artificial neural networks (ANN), was employed to an experimental dataset obtained from torsional shear tests on dry and saturated crushed soft rocks to predict the water-induced particle breakage potential (I D), peak friction angle (PFA), and residual friction angles (RFA). The experimental I D – PFA and I D – RFA correlations were also predicted using ANN model for all the three outputs (I D , PFA, RFA) with very low errors. [Display omitted] • Torsional shear testing on geomaterials of different geological origins was performed. • Water-induced degradation index and friction angles were experimentally determined. • An image based artificial neural networks (ANN) model was used. • The optimized ANN model predicted the degradation index and friction angles. • The degradation index – friction angle relationship was also predicted by the ANN model. [ABSTRACT FROM AUTHOR]

• The influence of coarse aggregate content on the early age transient properties are been studied. • The Mohr-Coulomb criteria was analyzed by varying the coarse aggregate volume ratio. • The cohesion development behavior of the 3D printable concrete was significantly different when compared to the mortar. • The coarse aggregate content was contributing to the angle of friction development with increase in rest time. This study deals with the criticality of binder-coarse aggregate interaction in the early age properties of 3D printable concrete (3DPC). The concrete with coarse aggregate (CA) behaves as two-phase material and has different rheological behavior. The transient early age concrete material properties are significant in simulating the plastic material yielding and elastic buckling failure patterns of 3DPC. Triaxial compression test (TCT) was adopted to measure apparent transient properties of 3DPC by Mohr-Coulomb criteria. Though this test methodology was adopted by some researches earlier for 3D printable mortars, a contradictory failure pattern was observed for 3DPC with CA of size 4 mm to 8 mm. The unconfined uniaxial compressive test (UUCT) was also performed to measure the green compressive strength and failure patterns were observed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Destructuring settlements due to frost heave during the structures' exploitation are often not taken into account at the designing stage, although they are indirectly related to the bearing capacity of the soils. The objective of this research was analyzing the effect of the number of freezing-thawing cycles on the strength characteristics of soils. A paired experiment with various initial parameters (void ratio, initial moisture content, and the number of freezing-thawing cycles) was carried out. According to the experimental results, the cohesion largely depends on the above parameters which might lead to its decrease by up to three times. The angle of internal friction demonstrated an indefinite behavior during the freeze-thaw cycles, which is confirmed by a literature review. Freezing–thawing cycles significantly decrease the soil bearing capacity: up to 44% after 10 freezing-thawing cycles for soil with e = 0.55 and   w = 16.5 % . However, in the case of e = 0.75 and w = 22.6 % , it increased by 33%. A program based on the least-squares method was used to calculate the approximation coefficients of the dependence describing the changes in strength characteristics from the abovementioned parameters. Changes in strength characteristics must be taken into account when designing structures, as they can lead to additional settlement or even subsidence of the foundations. [ABSTRACT FROM AUTHOR]

This paper describes the stability calculations of the most common road embankments slopes and their results using the modified Bishop method. By searching for the smallest possible effective angle of internal friction of the different slope steepness embankments, the possible different bases of the embankment, the weight of the embankment soil, the load caused by transport and the location of load application (shoulder) were evaluated. Analyzing the obtained calculation results, it was determined that at a slope of 1:2 (26.57°) steepness, to ensure slope stability, the calculated effective internal friction angle of the embankment soil should be φʹd ≥ 28.5°, and at a slope of 1:1.75 (29.74°) steepness – φʹd ≥ 29.8°. When the slope is 2:3 (33.69°) steepness, the stability of the slope cannot be guaranteed. [ABSTRACT FROM AUTHOR]

Analysis of slope stability is of critical importance in any open cast. A slope failure is a potential hazard as it can cause loss of lives of workers and economic losses that may lead to complete closure of the mine. The fundamental modes of failure are however varried and complex thus need for their indepth analysis. Such slope failure modes are guided by engineering geological condition of rock mass which differs from site to site, from sample to sample. This work was focussed at studying slope stability using numerical modells. The aim of the project is to know how and assess the usability of FLAC/slope and OASYS geoengineering software in determination of slope stability. Usage of these two softwares were a bit complicarted at the start of the analysis, however, with time we understood clearly how to use them and it can be concluded that they are user. Parametric studies led to a conclusion that angle of the slope plays a critical role and governs stability of slopes. Safety factors ranged from a value 0.64 way up to a value 1.38, for a depth variation from 10M110M while keeping the slope angle constant 45 degrees. This clearly elucidated that increase in bench height or depth of the mine leads to a significant decrease of safety, hence decreased stability of the respective slope. It could be recommended that the overall slope angle should be maintained at about 35 degrees or less since at an elevation of 100M, safety factors were found to exceed 1.2, which is deemed to be safer. Objectives of this study were therefore achieved, and we could recommend that in order to improve reliability of the model results, the models should first undergo field callibration through piezometric monitoring techniques in varried mining sites and varried conditions. [ABSTRACT FROM AUTHOR]

This paper presents the results of a laboratory study on the evaluation of the shear strength of compacted iron ore tailings (IOT) treated lateritic soil. Lateritic soil used was treated with 0 up to 16% IOT by weight of dry soil. Test performed include index test, compaction (using British Standard Light, BSL and West Africa Standard, WAS energies) and shear strength test. One-way analysis of variance was carried out using Microsoft Excel to determine the level of significance of IOT on the treated soil. The results of the triaxial test show that there is an improvement in the shear strength of soil with the improvement of its shear strength parameters (cohesion and angle of internal friction). Cohesion values decreased from 0 up to 8% IOT content and then increased while the angle of internal friction risen from 0 up to 8% IOT content and then decreased. Also, from the triaxial test carried out with varying cell pressures from 100 to 300 kN/m2, an increase in shear strength parameters and shear strength were recorded. The shear strength increased in value by 49.79% and 18.15% for BSL and WAS compaction at 8% IOT content, respectively. Statistical analysis carried out on the results using analysis of variance (ANOVA) shows that IOT has a significant effect on the lateritic soil. An optimal blend of 8% IOT improved the shear strength of the soil and can be used for geotechnical engineering applications such as roads and embankments.