The Research of Slope Stability Based on Unsaturated Soil Theory

2014 ◽  
Vol 937 ◽  
pp. 590-593
Author(s):  
Chang Qing Shao ◽  
Nan Zhang ◽  
Feng Lan Lv
Keyword(s):  
Unsaturated Soil ◽  
Evaluation Methods ◽  
Rainfall Infiltration ◽  
Stability Factor ◽  
Analysis Method ◽  
Infiltration Process ◽  
Strong Activity ◽  
The Matrix ◽  
Matrix Suction ◽  
The Stability

With the deep landslide induced by rainfall or more in practice, the existing evaluation methods are not suitable for to explain this kind of landslide during rainfall, which is the phenomenon of strong activity. This paper tries to improve existing methods for analyzing the stability of the landslide, the article set up to consider soil stability analysis method of the matrix suction side article discusses rainfall infiltration process middle side matrix suction changes impacting on the stability of the landslide, the preliminary discussion on the effect of rainfall on deep landslide are studied. Considering soil of the side of the evaluation methods of matrix suction jettisoned traditional saturated unsaturated soil mechanics analysis method, it can well reflect the process of rainfall infiltration, the matrix suction decreases, and the inter-atomic forces, stability factor to reduce the process, providing a train of thought for landslides evaluation.

Stability Analysis of Unsaturated Soil Slopes under Rainfall Infiltration

2012 ◽  
Vol 594-597 ◽  
pp. 126-129 ◽  
Author(s):  
Rong Fang Zhou ◽  
Xue Wen Lei ◽  
Qing Shan Meng ◽  
Cong Lin
Keyword(s):  
Unsaturated Soil ◽  
Equivalent Plastic Strain ◽  
Material Model ◽  
Rainfall Infiltration ◽  
Finite Element Program ◽  
Soil Material ◽  
Element Program ◽  
Stability Of Slope ◽  
Transient Seepage ◽  
The Stability

The principle of effective stress based on unsaturated soil material model and the boundary conditions of rainfall infiltration on the slope are introduced. The numerical model is built according to the example, and then the ABAQUS finite element program, which is combined with fluid-solid coupling, is used to simulate the problem of transient seepage field caused by rainfall infiltration. With the powerful post processing functions ability of ABAQUS program, we can observe the variation law with the time of pore-pressure distribution and displacement field and equivalent plastic strain. Moreover, the effect on the stability of slope under rainfall infiltration is analyzed.

Second Canadian Geotechnical Colloquium: Appropriate concepts and technology for unsaturated soils

1979 ◽  
Vol 16 (1) ◽  
pp. 121-139 ◽  
Author(s):  
D. G. Fredlund
Keyword(s):  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Earth Pressure ◽  
Saturated Soil ◽  
Engineering Practice ◽  
The Matrix ◽  
Matrix Suction

A practical science has not been fully developed for unsaturated soils for two main reasons. First, there has been the lack of an appropriate science with a theoretical base. Second, there has been the lack of an appropriate technology to render engineering practice financially viable.This paper presents concepts that can be used to develop an appropriate engineering practice for unsaturated soils. The nature of an unsaturated soil is first described along with the accompanying stress conditions. The basic equations related to mechanical properties are then proposed. These are applied to practical problems such as earth pressure, limiting equilibrium, and volume change.An attempt is made to demonstrate the manner in which saturated soil mechanics must be extended when a soil is unsaturated. Two variables are required to describe the stress state of an unsaturated soil (e.g., (σ – ua) and (ua – uW). There is a smooth transition from the unsaturated case to the saturated case since the pore-air pressure becomes equal to the pore-water pressure as the degree of saturation approaches 100%. Therefore, the matrix suction (i.e., (ua – uW) goes to 0 and the pore-water pressure can be substituted for the pore-air pressure (i.e., (σ – uW)).The complete volumetric deformation of an unsaturated soil requires two three-dimensional constitutive surfaces. These converge to one two-dimensional relationship for a saturated soil. The shear strength for an unsaturated soil is a three-dimensional surface that reduces to the conventional Mohr–Coulomb envelope for a saturated soil.The manner of applying the volumetric deformation equations and the shear strength equation to practical problems is demonstrated. For earth pressure and limiting equilibrium problems, the unsaturated soil can be viewed as a saturated soil with an increased cohesion. The increase in cohesion is proportional to the matrix suction of the soil. For volume change problems it is necessary to have an indication of the relationship between the various soil moduli.There is a need for further experimental studies and case histories to substantiate the proposed concepts and theories.

Reliability Analysis on Yuwangbian Slop Based on Monte-Carlo Simulation

2011 ◽  
Vol 250-253 ◽  
pp. 3934-3940
Author(s):  
Yi Fang Feng ◽  
Hua Zhi Zhang ◽  
Yu Wang ◽  
Qing Jun Zuo
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Reliability Analysis ◽  
Working Condition ◽  
Actual Condition ◽  
Stability Factor ◽  
Analysis Method ◽  
Loess Slope ◽  
The Monte Carlo Method ◽  
The Stability

Based on the Yuwangbian high loess slope, which is located in Xi'an Yanta District, the basic principle of Monte-Carlo method is presented. By means of geotechnical engineering and geotechnical environment emulation software Geostudio-slope/w and based on Morgenstern-Price slope stability analysis method, the reliability and stability of the slope are analyzed under different kinds of working condition. The stability factor, reliability index and failure probability under the corresponding working conditions has been obtained. The results coincide with the actual condition, which makes the Geostudio software combine with the Monte-Carlo method and provides reference for the reliability analysis of loess slope.

scholarly journals Numerical Analysis of Unsaturated Soil Slopes under Rainfall Infiltration Based on the Modified Glasgow Coupled Model

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Guoqing Cai ◽  
Mengzi Li ◽  
Bowen Han ◽  
Kenan Di ◽  
Qianqian Liu ◽  
...  
Keyword(s):  
Unsaturated Soil ◽  
Fluid Velocity ◽  
Coupled Model ◽  
Rainfall Infiltration ◽  
Secondary Development ◽  
Infiltration Process ◽  
Integration Algorithm ◽  
Soil Slopes ◽  
Implicit Integration Algorithm ◽  
Numerical Program

An ABAQUS UMAT subroutine was used for the secondary development of the established coupled hydromechanical constitutive model of unsaturated soil considering the effect of the microscopic pore structure. Combined with Euler’s backward implicit integration algorithm, a numerical program was established for simulating the proposed model. The developed numerical program was used to simulate the rainfall infiltration process of an actual slope engineering example, and the effects of rainfall intensity and rainfall duration on the pore pressure, fluid velocity, and displacement of the unsaturated soil slope were analyzed. The results show that the developed numerical program can reasonably analyze the changes in the seepage field and displacement field of unsaturated soil slopes under rainfall infiltration.

Numerical Analysis Method for Dynamic Stability of a High and Steep Rock Slope in the Sichuan Wenchuan Earthquake

2011 ◽  
Vol 261-263 ◽  
pp. 1182-1190 ◽  
Author(s):  
Shi Guo Xiao ◽  
Wen Kai Feng
Keyword(s):  
Reduction Method ◽  
Time History ◽  
Time History Analysis ◽  
Strength Reduction ◽  
Stability Factor ◽  
Strength Reduction Method ◽  
Analysis Method ◽  
History Analysis ◽  
Seismic Force ◽  
The Stability

Near-field ground shock features are analyzed according to the seismological record of the May 12 Wenchuan earthquake made at the Wolong observation station. A numerical analysis model is established by taking the record as the input seismic load and a real high and steep rock slope on the bank of the Zipingpu Reservoir. The acceleration response and shear strain increment distribution features at different locations of the slope under horizontal seismic force are analyzed using Plaxis software. The moment when the widest plastic zone occurs for the slope is obtained by time history analysis. The corresponding stability factor of the slope at that moment is calculated using the strength reduction method (including shear strength and tensile strength). The above is the Time History Analysis–Strength Reduction Method presented in this article. In addition, the stability factor of the slope can be calculated using the pseudostatic method by taking the seismic force as the external load. This is the Time History Analysis–Pseudostatic method put forward in this paper. Analysis results demonstrate that, as far as the studied high and steep slope is concerned, at 31.89 s, the stability factor calculated with the Time History Analysis–Strength Reduction Method is 1.004, which is slightly larger than the 0.833 obtained using the Time History Analysis–Pseudostatic Method (Spencer method). Both results demonstrate that there is collapse and sliding failure of the localized rock mass at the top of the slope at that moment because of joint fracture. Field investigation after the earthquake further verified the calculation result, proving to a certain degree the rationality of the analysis method presented.

scholarly journals An Approach to Assess the Stability of Unsaturated Multilayered Coastal-Embankment Slope during Rainfall Infiltration

2019 ◽  
Vol 7 (6) ◽  
pp. 165 ◽  
Author(s):  
Jian-feng Zhu ◽  
Chang-fu Chen ◽  
Hong-yi Zhao
Keyword(s):  
Safety Factor ◽  
Search Algorithm ◽  
Random Search ◽  
Rainfall Infiltration ◽  
Sliding Surface ◽  
Linear Distribution ◽  
Groundwater Levels ◽  
Embankment Slope ◽  
The Matrix ◽  
The Stability

This study aims to develop a simple but effective approach to investigate the stability of an unsaturated and multilayered coastal-embankment slope during the rainfall, in which a Random Search Algorithm (RSA) based on the random sampling idea of the Monte Carlo method was employed to obtain the most dangerous circular sliding surface, whereas the safety factor of the unsaturated slope was calculated by the modified Morgenstern–Price method. Firstly, two typical distributions of matric suction were illustrated and the associated methods for determining the strength parameters of unsaturated soil were developed. Based on this, the Morgenstern–Price method was further modified to calculate the safety factor, and RSA was adopted to locate the most dangerous sliding surface of the unsaturated multilayered coastal-embankment slope. Finally, the slope breaking process under rainfall infiltration was simulated through continuously searching the critical slip surfaces under different groundwater levels by RSA. The results indicated that the stability of the unsaturated embankment slope was gradually deteriorated with the increase of rainfall infiltration. It was also found that both of the distributions of the matrix suction (ua-uw) and the suction angle (φb) had significant effects on the safety factor of the embankment slope. Basically, linear distribution of (ua-uw) along the depth and linear relationship between φb and (ua-uw) should be adopted in assessing the stability of the unsaturated multilayered coastal-embankment slope.

scholarly journals Supporting Characteristics of Soldier Piles for Foundation Pits under Rainfall Infiltration

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Changxi Huang ◽  
Xinghua Wang ◽  
Min Zhang ◽  
Hao Zhou ◽  
Yan Liang
Keyword(s):  
Unsaturated Soil ◽  
Moisture Absorption ◽  
Integral Transform ◽  
Earth Pressure ◽  
Rainfall Infiltration ◽  
Residue Theorem ◽  
Soil Permeability ◽  
Design Code ◽  
Rainfall Duration ◽  
The Stability

The evolution of supporting characteristics of soldier piles for foundation pits under rainfall infiltration is described in this paper. Based on the Richards seepage equation and earth pressure theory considering the effect of intermediate principal stress of unsaturated soil, the approximate solution of permeability coefficient in unsaturated soil is developed using the Laplace integral transform and residue theorem. The transition of the boundary condition from flux boundary to head boundary is taken into account, and the rationality of the solution is verified. The safety factor of soldier piles’ stability against overturning is derived, and its displacements are obtained by the finite-difference method. The results show that the stability of soldier piles gradually decreases with rainfall duration, and the actual embedded depth of the pile should be greater than the minimum embedded depth specified by the design code. The displacement response of pile top lags behind the rainfall and increases later in the rainfall period. The hysteresis time is shortened with the increase of soil permeability. Considering moisture absorption, the effect of rainfall on the properties of retaining structure is limited for the homogeneous soils with low suction or permeability.

Research on Calculation Method of the Stability Factor of Variable Cross-Sectional Concrete Filled Steel Tubular Laced Columns

2014 ◽  
Vol 587-589 ◽  
pp. 1420-1423
Author(s):  
Zhi Jing Ou ◽  
Lei Huang ◽  
Qiao Ling Yan
Keyword(s):  
Slenderness Ratio ◽  
Stability Factor ◽  
Computational Formula ◽  
Variable Cross ◽  
Analysis Method ◽  
Element Analysis ◽  
Cross Sectional ◽  
Finite Element Analysis Method ◽  
The Finite Element Analysis ◽  
The Stability

The finite element analysis method of variable cross-sectional Concrete-Filled Steel Tubular (CFST) laced columns is put forward. The influence of longitudinal elements slope and slenderness ratio on stability factor are analyzed, and the computational formula of slenderness ratio of variable cross-sectional CFST laced columns is presented. On the basis of the analytical results, a rational methodology for calculating the stability factor of four-element variable cross-sectional CFST laced columns is proposed.

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