scholarly journals An Experimental Study of Nailed Soil Slope Models: Effects of Building Foundation and Soil Characteristics

2021 ◽  
Vol 11 (16) ◽  
pp. 7735
Author(s):  
Mahmoud Mohamed ◽  
Mohd Ahmed ◽  
Javed Mallick
Keyword(s):  
Lateral Displacement ◽  
Slope Angle ◽  
Earth Pressure ◽  
Soil Mass ◽  
Material Strength ◽  
Soil Slope ◽  
Strength Failure ◽  
Economic Method ◽  
Building Foundation ◽  
Devices And Instruments

A soil nailing system is a proven effective and economic method used to stabilize earth slopes from the external (factors increasing the shear stress) and internal (factors decreasing material strength) failure causes. The laboratory models with scales of 1:10 are used to study the behavior of nailed soil slope with different soil and building foundation parameters. The models consist of Perspex strips as facing and steel bars as a nailing system to increase the stability of the soil slope. The models of sand beds are formed using an automatic sand raining system. Devices and instruments are installed to monitor the behavior of soil-nailed slope during and after construction. The effect of the soil type, soil slope angle, foundation width and position on the force mobilized in the nail, lateral displacement of the slope, settlement of the foundation and the earth pressure at the slope face, under and behind the soil mass at various foundation pressures, has been observed. It is found that the increase of soil density reduces both slopes facing displacement and building foundation settlements. The slope face displacement and footing settlement will increase with an increase in the width of the foundation and foundation position near the crest of the slope.

scholarly journals Determination of pressure in the near-ground space pile terminated and broadening of the surface

2018 ◽  
Vol 251 ◽  
pp. 04062
Author(s):  
Natalia Kupchikova
Keyword(s):  
Numerical Modeling ◽  
Circular Cross Section ◽  
Analytical Form ◽  
Soil Mass ◽  
Software Systems ◽  
Discrete Method ◽  
Building Foundation ◽  
Geological Conditions ◽  
Complex Engineering

The article deals with the problem of determining the stress state of a complex pile structure with end broadening in the form of a sphere in the soil mass in the analytical form by a discrete method. The calculation schemes for determining the stress tensor at the boundary of the pile of square and circular cross-section with expansions in the soil massif are shown. The elements of the polynomial are found by the discrete method in rectangular and spherical coordinates, which is a cumbersome complex mathematical apparatus for a modern design engineer. The stresses are determined. At present, as the analysis has shown, the solution of complex geotechnical problems of soil bases and foundations for different types of loads in numerical modeling is carried out using modern software. Numerical modeling and calculation with the help of specialized software systems allows to consider the system “building-foundation-ground foundation”, as dynamic, integrally developing. However, the interaction of the components of this system requires a theoretical justification of the resistance of foundations in the ground environment, especially in complex engineering-geological conditions.

scholarly journals Erosion Failure of a Soil Slope by Heavy Rain: Laboratory Investigation and Modified GA Model of Soil Slope Failure

2019 ◽  
Vol 16 (6) ◽  
pp. 1075 ◽  
Author(s):  
Xiaofei Jing ◽  
Yulong Chen ◽  
Changshu Pan ◽  
Tianwei Yin ◽  
Wensong Wang ◽  
...  
Keyword(s):  
Laboratory Investigation ◽  
Slope Failure ◽  
Slope Angle ◽  
Heavy Rain ◽  
Annual Rainfall ◽  
Soil Slope ◽  
Saturated Zone ◽  
Wetting Front ◽  
Rainfall Condition ◽  
The Impact

Rainfall has been identified as one of the main causes for slope failures in areas where high annual rainfall is experienced. The slope angle is important for its stability during rainfall. This paper aimed to determine the impact of the angle of soil slope on the migration of wetting front in rainfall. The results proved that under the same rainfall condition, more runoff was generated with the increase of slope angle, which resulted in more serious erosion of the soil and the ascent of wetting front. A modified Green-Ampt (GA) model of wetting front was also proposed considering the seepage in the saturated zone and the slope angle. These findings will provide insights into the rainfall-induced failure of soil slopes in terms of angle.

scholarly journals Application of Limit Equilibrium Analysis and Numerical Modeling in a Case of Slope Instability

2020 ◽  
Vol 12 (21) ◽  
pp. 8870
Author(s):  
Fhatuwani Sengani ◽  
François Mulenga
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Limit Equilibrium ◽  
Slope Angle ◽  
Road Construction ◽  
Soil Mass ◽  
Slope Instability ◽  
Equilibrium Analysis ◽  
Limit Equilibrium Analysis ◽  
The Common

The application of limit equilibrium analysis and numerical simulation in case of slope instability is described. The purpose of the study was to use both limit equilibrium methods (LEMs) and numerical simulations (finite element method (FEM)) to understanding the common factor imposing the selected slope into slope instabilities. Field observations, toppling analysis, rotational analysis, and numerical simulations were performed. The results of the study showed that the selected unstable slopes were associated with the sliding types of toppling; it was observed that the slopes were governed by tension cracks and layered soil mass and dominated with approximately two joints sets throughout. The simulated factor of safety (FoS) of the slopes composed of clay soil was denoted to be prone to slope instability while others were categorized as moderately stable. The simulated FoS of the slopes correlated very well with the visual observations; however, it is anticipated that properties of soil mass and other characteristics of the slopes contributed largely to the simulated FoS. The sensitivity of the model was further tested by looking into the effect of the slope angle on the stability of the slope. The results of the simulations showed that the steeper the slope, the more they become prone to instability. Lastly, Phase 2 numerical simulation (FEM) showed that volumetric strain, shear stress, shear strain, total displacement, and σ1 and σ3 components of the slope increase with the stages of the road construction. It was concluded improper road construction, steepness of the slope, slope properties (soil types), and multiple geological features cutting across are the common mechanisms behind the slope instability.

Study on the applicability of a retaining wall using batter piles in clay

2016 ◽  
Vol 53 (8) ◽  
pp. 1195-1212 ◽  
Author(s):  
Minsu Seo ◽  
Jong-Chul Im ◽  
Changyoung Kim ◽  
Jae-Won Yoo
Keyword(s):  
Lateral Displacement ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Integrated System ◽  
Element Analysis ◽  
Test Execution ◽  
The Earth ◽  
National University ◽  
Clay Ground ◽  
Batter Piles

A retaining wall using batter piles has been developed and studied to improve existing earth-retaining structures at Pusan National University. The earth-retaining method is a temporary excavation method using an integrated system of front supports and batter piles. The batter piles connected to the front supports significantly reduce the earth pressure acting on the front supports by distributing it to batter piles to increase structural stability. In this study, the existence of batter piles, the fixity of the tips of front supports or batter piles, the spacing between batter piles, and the verticality of front supports are varied across model tests. The lateral displacement of the earth-retaining wall decreased by approximately 40% and 15% for the existence and fixity of batter piles, respectively. The applicability of the earth-retaining method using batter piles has been verified with finite element analysis and field test execution in clay ground.

scholarly journals Numerical modeling of progressive failure and its implications for spreads in sensitive clays

2013 ◽  
Vol 50 (9) ◽  
pp. 961-978 ◽  
Author(s):  
Ariane Locat ◽  
Hans Petter Jostad ◽  
Serge Leroueil
Keyword(s):  
Progressive Failure ◽  
Limit Equilibrium ◽  
Pressure Ratio ◽  
Earth Pressure ◽  
High Sensitivity ◽  
Failure Surface ◽  
Soil Mass ◽  
Initiation And Propagation ◽  
Failure Propagation ◽  
Steep Slopes

Spreads are a type of large landslide occurring in sensitive clays. Stability analyses using the limit equilibrium method give factors of safety that are too large and are therefore not applicable to this type of landslide. The progressive failure mechanism is believed to explain the initiation and propagation of the failure surface and the dislocation of the soil mass in horsts and grabens, typical of spreads. A numerical method is presented to identify the parameters influencing progressive failure and to validate the application of this mechanism to spreads. The method evaluates the stresses acting in the slope before failure and models the initiation and propagation of the progressive failure. It is demonstrated that high, steep slopes, with a large earth pressure ratio at rest, are more susceptible to progressive failure and the failure surface propagates over a large distance. Failure is more likely to occur when soil with high brittleness is involved. Soil with low strength at large deformation induces failure propagation over a larger distance. Eastern Canadian clays can exhibit high sensitivity and large brittleness during shear and are susceptible to progressive failure, which explains the occurrence of spreads in these soils.

scholarly journals A Stochastic Rockfall Model Related to Random Ground Roughness Based on Three-Dimensional Discontinuous Deformation Analysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Lu Zheng ◽  
Zhiyuan Zhu ◽  
Qi Wei ◽  
Kaihui Ren ◽  
Yihan Wu ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Lateral Displacement ◽  
Grid Point ◽  
Slope Angle ◽  
Three Dimensional ◽  
Discontinuous Deformation Analysis ◽  
Cumulative Distribution ◽  
Deformation Analysis ◽  
Discontinuous Deformation ◽  
The Impact

The use of feasible 3-D numerical methods has become essential for addressing problems related to rockfall hazard. Although several models with various degrees of complexity are available, certain trajectories and impact dynamics related to some model inputs could fall in the rockfall observations area but are rarely calibrated against reflecting its range, especially the lateral deviations. A major difficulty exists in the lack of simulating the apparent randomness during the impact-rebound process leading to both ground roughness and block irregularities. The model presented here is based on three-dimensional discontinuous deformation analysis (3-D DDA). Despite similarities to previous simulations using 3-D DDA, the model presented here incorporates several novel concepts: (1) ground roughness is represented as a random change of slope angle by height perturbation at a grid point in DEM terrain; (2) block irregularities are modelled directly using polyhedron data; (3) a scaled velocity restitution relationship is introduced to consider incident velocity and its angle. Lateral deviations of rebound velocity, both direction and value, at impact are similarly accounted for by perturbing the ground orientation laterally, thus inducing scatter of run-out directions. With these features, the model is capable to describe the stochastic rockfall dynamics. In this study, 3-D DDA was then conducted to investigate the dynamic behavior of the rockfall and examine the role of sphericity of the rock block travelling on bench slopes with different ground roughness levels. Parametric analyses were carried out in terms of cumulative distribution function (CDF) to investigate for spatial distribution (both runout distance and lateral displacement), velocity and jumping height. The effects of block shape and ground roughness revealed by these factors were discussed. It suggests that ground roughness amplifies the randomness and plays important roles on the dynamic behavior of the system; irregularity from block sphericity will further amplify the randomness especially when the size of the rock is relatively small compared to the roughness level. Both irregularities should be taken into consideration in simulating rockfall problems. Further calibration of the new model against a range of field datasets is essential.

scholarly journals Deterministic and Probabilistic Analysis of Dasdhunga Soil Slope along Narayangarh-Mugling Road Section

2021 ◽  
Vol 6 ◽  
pp. 187-198
Author(s):  
Saurav Shrestha ◽  
Indra Prasad Acharya ◽  
Ranjan Kumar Dahal
Keyword(s):  
Limit Equilibrium ◽  
Water Pressure ◽  
Slope Angle ◽  
Friction Angle ◽  
Probability Of Failure ◽  
Soil Slope ◽  
Extrinsic Factors ◽  
Stability Of Slopes ◽  
Road Section ◽  
Truncated Normal

Instability of slopes is usually governed by a combination of intrinsic and extrinsic factors. The inherent variability of parameters make the problem probabilistic rather than a deterministic one. This research deals with evaluation of stability of slopes with the calculation of the factor of safety of Dasdhunga soil slope along Narayangarh- Mugling road section under different rainfall conditions through the use of coupled finite element and limit equilibrium method in GeoStudio and the determination of probability of failure by sliding, modeled as infinite slopes by using Monte Carlo simulation in R-Studio. Mean, standard deviation, minimum and maximum values of the parameters like- friction angle, cohesion and unit weight were computed from eight samples of the slope. The pore water pressure developed and its corresponding statistical data for different rainfall conditions were computed from FEM based SEEP/W simulation. The above parameters are assumed to follow truncated normal probability distribution function and the geometric parameters like height and slope angle are regarded as constant parameters. It was observed that the safety factors for theslopeis low in high intensity-low duration rainfalls and the probability of failure is high. The tendency to fail increases as the return period of rainfall increases and viceversa. Sensitivity analysis performed in both deterministic and probabilistic methods showed that friction angle is the most sensitive.

scholarly journals Model Test and Numerical Simulation of Single Pile Response under Combined Loading in Slope

2020 ◽  
Vol 10 (17) ◽  
pp. 6140
Author(s):  
Jianwei Zhang ◽  
Xiaoju Wang ◽  
Hao Wang ◽  
Hongyu Qin
Keyword(s):  
Numerical Simulation ◽  
Model Test ◽  
Lateral Displacement ◽  
Slope Angle ◽  
Combined Loading ◽  
Single Pile ◽  
Soil Pressure ◽  
Foundation Design ◽  
Sloping Ground ◽  
Horizontal Thrust

Vertical loads are commonly transferred by piles primarily in the upper structures. However, lateral loads are also significant compared with vertical loads in pile foundation design. Compared with a pile on level ground, there are many particular characteristics in a pile that is on sloping ground. These characteristics depend on the combined loading and the magnitude of the soil lateral displacement. In order to investigate the pile’s bearing characteristics, a model test was conducted and ABAQUS software was adopted to conduct 3D numerical simulation of a single pile with different slope angles under combined loads. The experimental results indicated that (1) the soil pressure along the slope direction was smaller than the other side, resulting in an asymmetry of the slope soil around the pile, and in turn introducing a horizontal thrust to the pile; (2) with the increase of slope angle, the horizontal thrust increased while the single pile’s bearing capacity decreased; (3) the vertical load caused more pile horizontal displacement with the growth of slope angle; and (4) the pile’s moment and the displacement also increased with the growth of the slope angle. The findings in this study can provide a useful reference in the design of piles or anti-slide piles in sloping ground.

scholarly journals Load-Settlement Response of A Footing Over Buried Conduit in A Sloping Terrain: A Numerical Experiment-Based Artificial Intelligent Approach

2021 ◽  
Author(s):  
Muhammad Umer Arif Khan ◽  
Sanjay Kumar Shukla ◽  
Muhammad Nouman Amjad Raja
Keyword(s):  
Machine Learning ◽  
Applied Load ◽  
Slope Angle ◽  
Unit Weight ◽  
Burial Depth ◽  
Multi Layer Perceptron ◽  
Soil Slope ◽  
Percentage Difference ◽  
Constrained Modulus ◽  
Sloping Terrain

Abstract Settlement estimation of a footing located over a buried conduit in a sloping terrain is a challenging task for practicing civil/geotechnical engineers. In the recent past, the advent of machine learning technology has made many traditional approaches antiquated. This paper investigates the viability, development, implementation, and comprehensive comparison of five artificial intelligence-based machine learning models, namely, multi-layer perceptron (MLP), Gaussian processes regression (GPR), lazy K-Star (LKS), decision table (DT), and random forest (RF) to estimate the settlement of footing located over a buried conduit within a soil slope. The pertaining dataset of 3600 observations was obtained by conducting large-scale numerical simulations via the finite element modelling framework. After executing the feature selection technique that is correlation-based subset selection, the applied load, total unit weight of soil, constrained modulus of soil, slope angle ratio, hoop stiffness of conduit, bending stiffness of conduit, burial depth of conduit, and crest distance of footing were utilized as the influence parameters for estimating and forecasting the settlement. The predictive strength and accuracy of all models mentioned supra were evaluated using several well-established statistical indices such as Pearson’s correlation coefficient (r), root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), scatter index (SI), and relative percentage difference (RPD). The results showed that among all the models employed in this study, the multi-layer perceptron model has shown better results with r, RMSE, NSE, SI, and RPD values of (0.977, 0.298, 0.937, 0.31, and 4.31) and (0.974, 0.323, 0.928, 0.44 and 3.75) for training and testing dataset, respectively. The sensitivity analysis revealed that all the selected parameters play an important role in determining the output value. However, the applied load, constrained modulus, unit weight, slope angle ratio, hoop stiffness have the highest strength with the relative importance of 18.4%, 16.3% and 15.3%, 13.8%, 11.4%, respectively. Finally, the model was translated into a functional relationship for easy implementation and can prove useful for practitioners and researchers in predicting the settlement of a footing located over a buried conduit in a sloping terrain.

scholarly journals Landslide Failure Mechanisms of Dispersive Soil Slopes in Seasonally Frozen Regions

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Lixiang Wang ◽  
Xiaoming Yuan ◽  
Miao Wang
Keyword(s):  
Soil Structure ◽  
Theoretical Calculations ◽  
Substantial Reduction ◽  
Soil Mass ◽  
Soil Slope ◽  
Soil Layers ◽  
Landslide Occurrence ◽  
Soil Instability ◽  
Seasonally Frozen Regions ◽  
Dispersive Soil

Hydraulic projects with dispersive soil in seasonally frozen regions are susceptible to landslide failures. The mechanism of such landslide failures has not been fully understood thus far; therefore, it was investigated in this study by using on-site surveys, laboratory tests, and theoretical calculations. The results showed that the landslides of dispersive soil in seasonally frozen regions could be categorized as shallow-seated landslides and deep-seated landslides. The preconditions for landslide occurrence were soil mass looseness and cracks, caused by freeze-thawing. The degradation of dispersive soil led to a rapid influx of water into the soil. The reason for shallow-seated landslides was that the numerous sodium ions present in the soil mass dissolved in water and damaged the soil structure, resulting in a substantial reduction in shear strength. The reason for deep-seated landslides, however, was the erosion due to rainfall infiltration after the shallow-seated landslides caused tensile cracks at the top of the slope, leading to soil instability. Landslide failures occurred when the dispersing soil slope underwent freeze-thawing and saturated soaking. The sliding surface was initiated at the top of the slope and gradually progressed to the bottom along the interface between the soil layers.

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