scholarly journals Investigation of the Role of Crown Crack in Cohesive Soil Slope and Its Effect on Slope Stability Based on Extended Finite Element Method

2021 ◽  
Author(s):  
Yiding Bao ◽  
Yuchao Li ◽  
Yansong Zhang ◽  
Jianhua Yan ◽  
Xin Zhou
Keyword(s):  
Slope Stability ◽  
Extended Finite Element Method ◽  
Slope Failure ◽  
Slip Surface ◽  
Natural Soil ◽  
Tension Zone ◽  
Soil Slope ◽  
Extended Finite Element ◽  
Soil Slopes

Abstract Tensile cracks in soil slopes, especially developing at the crown, have been increasingly recognized as the signal of slope metastability. In this paper, the role of crown cracks in natural soil slopes was investigated and their effect on stability was studied. A numerical slope model based on the extended finite element method (XFEM) simulating the tensile behavior of soil was used. Before the simulation, a numerical soil tensile test was applied to validate the use of XFEM on tensile behavior of soil. Slope failure was simulated by using strength reduction technique, which can determine the potential slip surface of slope. The simulation results show that the crown crack forms in natural soil slopes when the plastic zone starts penetrating, and therefore it is reasonable to consider the crown crack as the signal of slope metastability. A sensitivity analysis shows that cracks are at the position of the tension zone or very long can obviously affect the slope stability. The stress variation analysis from the initial deformation to slip surface penetration shows that the slope is at a state of compressive stress initially. When plastic zone starts to penetrate, the upper part of slope generates tension zone, but the extent of tension zone is limited until slope failure. This shows why tensile cracks are difficult to form and be stretched in the deep part of the slope. The application of XFEM on slope stability analysis can be used to assess the tensile strength of soil and predict slope failure disaster.

scholarly journals The Rise of Groundwater Due to Rainfall and the Control of Landslide by Zero-Energy Groundwater Withdrawal System

2018 ◽  
Vol 7 (2.29) ◽  
pp. 921 ◽  
Author(s):  
Shamsan Alsubal ◽  
Nasiman Sapari ◽  
Indra S.H. Harahap
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Slope Failure ◽  
Groundwater Table ◽  
Groundwater Withdrawal ◽  
Natural Soil ◽  
Soil Slope ◽  
Soil Permeability ◽  
Zero Energy ◽  
The Third

Slope failure is a common issue in tropical countries. The rise of groundwater table due to rainfall is one of the main triggering factors. There are several methods for slope stabilization such as soil nailing, retaining walls, cut and fill, vegetation and so on. Most of those methods are costly and we are in need for stabilizing methods that are more economical and easier to construct. This article introduces a new method for slope stability. This method is examined numerically and experimentally. It is represented in an automatic zero-energy groundwater withdrawal system to enhance slope stability. The system is validated in a pre-fabricated model to ensure that it works on natural soil slope. The numerical simulation is performed in Soilworks software with coupled seepage-slope stability analysis using finite element methods to check the safety factor with and without the system. The effectiveness of this method is investigated with various rainfall intensities and soil permeabilities. The results for slopes with the application of groundwater withdrawal system are compared with the results without the system. The results demonstrate the effectiveness of the proposed method in reducing groundwater table and enhancing slope stability. The factor of safety for the slope with high soil permeability drops from 1.312 before the rainfall to 1.292 and 0.93 after the third rainfall event for the slope with and without pumping groundwater respectively. For soil slope with moderate soil permeability, the factor of safety deteriorates from 1.314 to 1.157 at the end of the third day, while it remains stable with pumping groundwater. Matric suction is highly increased at the crest of the slope due to pumping. 

scholarly journals An Extended Finite Element Method (XFEM) Study on the Elastic T-Stress Evaluations for a Notch in a Pipe Steel Exposed to Internal Pressure

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 507
Author(s):  
K. Yakoubi ◽  
S. Montassir ◽  
Hassane Moustabchir ◽  
A. Elkhalfi ◽  
Catalin Iulian Pruncu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Extended Finite Element Method ◽  
Research Study ◽  
Extended Finite Element ◽  
T Stress ◽  
Cracked Structures ◽  
Element Method

The work investigates the importance of the K-T approach in the modelling of pressure cracked structures. T-stress is the constant in the second term of the Williams expression; it is often negligible, but recent literature has shown that there are cases where T-stress plays the role of opening the crack, also T-stress improves elastic modeling at the point of crack. In this research study, the most important effects of the T-stress are collected and analyzed. A numerical analysis was carried out by the extended finite element method (X-FEM) to analyze T-stress in an arc with external notch under internal pressure. The different stress method (SDM) is employed to calculate T-stress. Moreover, the influence of the geometry of the notch on the biaxiality is also examined. The biaxiality gave us a view on the initiation of the crack. The results are extended with a comparison to previous literature to validate the promising investigations.

Determination of three-dimensional shape of failure in soil slopes

2015 ◽  
Vol 52 (9) ◽  
pp. 1283-1301 ◽  
Author(s):  
Roohollah Kalatehjari ◽  
Ali Arefnia ◽  
Ahmad Safuan A Rashid ◽  
Nazri Ali ◽  
Mohsen Hajihassani
Keyword(s):  
Slope Stability ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Failure Surface ◽  
Small Scale ◽  
3D Shape ◽  
Finite Element Software ◽  
Soil Slopes ◽  
3D Slope Stability

This paper presents the application of particle swarm optimization (PSO) in three-dimensional (3D) slope stability analysis to determine the shape and direction of failure as the critical slip surface. A detailed description of adopted PSO is presented and a rotating ellipsoidal shape is introduced as the possible failure surface in the analysis. Based on the limit equilibrium method, an equation of factor of safety (FoS) was developed with the ability to calculate the direction of sliding (DoS) in its internal process. A computer code was developed in Matlab to determine the 3D shape of the failure surface and calculate its FoS and DoS. Then, two example problems were used to verify the applicability of the presented code, the first by conducting a comparison between the results of the code and PLAXIS-3D finite element software and the second by re-analyzing an example from the literature to find the 3D failure surface. In addition, a hypothetical 3D asymmetric slope was introduced and analyzed to demonstrate the ability of the presented method to determine the shape and DOS of failure in 3D slope stability problems. Finally, a small-scale physical model of a 3D slope under vertical load was constructed and tested in the laboratory and the results were re-analyzed and compared with the code results. The results demonstrate the efficiency and effectiveness of the presented code in determining the 3D shape of the failure surface in soil slopes.

Research on the Soil Slope Stability Based on Soil Strength Deterioration in Seasonal Frozen Areas

2011 ◽  
Vol 243-249 ◽  
pp. 4270-4273 ◽  
Author(s):  
Qi Ge ◽  
He Wu ◽  
Ya Feng Gong
Keyword(s):  
Slope Stability ◽  
Slope Failure ◽  
Experimental Tests ◽  
Melting Process ◽  
Road Transport ◽  
Shallow Landslide ◽  
Soil Slope ◽  
Strength Deterioration ◽  
Freezing Soil ◽  
The Road

Soil slope is one of the main parts of the road engineering. The stability of the slope is an essential prerequisite to ensure the safe operation of road transport. In seasonal frozen regions, shallow landslide hazards in soil slopes usually happen, which pose a serious threat to road safety operations. During the melting process, there forms stagnant water lubrication between the melting soil and freezing soil interface, which constitutes the weak interface of landslide hazard. Special methods to form the freezing – thawing (F-T) surface is designed, and takes consider the interface strength as the foundation of experimental tests, then opening to research the soil slope stability. Safety factor modification of the soil slope is presented. The conclusions of this paper present well theoretical and applied value to the regional slope failure analysis.

scholarly journals Coupled Hydro-Mechanical Analysis of Rainfall-Induced Instability of Non-Uniform Soil Slopes

2021 ◽  
Author(s):  
Manyu Wang ◽  
Yong Liu ◽  
Lu Yang ◽  
Jing Wu ◽  
Guilin Niu
Keyword(s):  
Hydraulic Conductivity ◽  
Flow Rate ◽  
Large Scale ◽  
Slope Failure ◽  
Water Pressure ◽  
Mechanical Analysis ◽  
Soil Slope ◽  
Arithmetic Average ◽  
Average Value ◽  
Soil Slopes

In recent years, more considerable attentions are paying on the hazards of large-scale landslides induced by heavy rainfall. However, the heterogeneity in hydraulic properties of soils may affect the seepage pattern of water infiltrated into soil slopes. Inspired by this fact, this paper aimed to evaluate the effect of the spatial variability in hydraulic conductivity on failure mechanism of an unsaturated soil slope subjected to rainfall infiltration, being implemented in the framework of a transient coupled hydro-mechanical analysis. The concept of random field was adopted to model the spatial randomness of saturated hydraulic conductivity ks following a uniform distribution. The finite element method was then incorporated to conduct Monte Carlo simulations. The resultant findings show that the mode of shallow slope failure is more likely to occur than the deep one due mainly to the highly variable distribution of ks near slope surface. Note that the decrease in the effective stress of soils resulting from the increase of pore water pressure is the most critical reason for the occurrence of slope failure. In addition, from the random element analyses results, it indicates that the value of Qari calculated by performing a deterministic analysis based on arithmetic average value kari gives a prediction of flow rate on average, but the calculated Qmax based on maximum value kmax provides a more conservative assessment on total flow rate across soil slope, which can offer useful suggestions for practitioners to take available measures to drain in advance.

Influence of Anisotropic Internal Friction Angle on the Stability of Uniform Soil Slopes

2012 ◽  
Vol 170-173 ◽  
pp. 270-273 ◽  
Author(s):  
Lian Wei Zhang
Keyword(s):  
Slip Surface ◽  
Friction Angle ◽  
Soil Slope ◽  
Critical Slip Surface ◽  
Obvious Effect ◽  
Anisotropic Friction ◽  
Change Of Direction ◽  
Soil Slopes ◽  
Anisotropic Soil ◽  
The Stability

The effect of anisotropy of friction angle in natural deposited soil on the stability of soil slopes was studied in this paper. Stability analysis was performed on a uniform soil slope with anisotropic friction angle. Spencer’s method was used, and the variation of friction angle was assumed to be linear to the change of direction of the slip surface. It was shown that 7-10 percent of change in safety factor might achieve within a 10m-highed anisotropic soil slope. It was also found from the analysis that that frictional anisotropy had no obvious effect on the location of critical slip surface.

scholarly journals Strength Characteristics and Slope Stability of Expansive Soil from Pingdingshan, China

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ju-yun Zhai ◽  
Xiang-yong Cai
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Expansive Soil ◽  
Friction Angle ◽  
Natural Soil ◽  
Soil Slope ◽  
The Finite Element Method ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
The Stability

By analyzing the characteristics of expansive soil from Pingdingshan, China, the shear strength parameters at different water contents, dry densities, and dry-wet cycles of expansive soil are obtained. It is found that, at higher soil-water content, the internal friction angle is 0° and the shallow layer of expansive soil slope will collapse and destroy; this has nothing to do with the height of the slope and the size of the slope. The parameters of soil influenced by atmosphere are the ones which have gone through dry-wet cycles, and the parameters of soil without atmospheric influence are the same as those of natural soil. In the analysis of slope stability, the shear strength parameters of soil can be determined by using the finite element method, and the stability coefficient of the expansive soil slope can be calculated.

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