scholarly journals Numerical Analysis of the Effects of Crack Characteristics on the Stress and Deformation of Unsaturated Soil Slopes

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 194 ◽  
Author(s):  
Liuxin Yang ◽  
Enlong Liu
Keyword(s):  
Pore Water ◽  
Unsaturated Soil ◽  
Crack Width ◽  
Evaporation Rate ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Infiltration Rate ◽  
Soil Slope ◽  
Soil Slopes ◽  
Stress And Deformation

Cracks induced by evaporation or rainfall have a great influence on the stability of unsaturated soil slopes, which can lead to landslides during the rainfall process. In order to study the effect of crack characteristics on the evolution of stress and deformation of unsaturated soil slopes, a series of numerical analyses under different conditions were performed using a coupled elastoplastic finite element program that we developed for unsaturated soil. When carrying out the numerical analyses, the effective stress for unsaturated soil proposed by Bishop and an elastoplastic double-hardening constitutive model for the soil skeleton were employed. The varying parameters, including the crack location, the discharge speed, evaporation rate, infiltration rate, and tensile strength, were investigated to study the coupling process of pore water pressure and deformation in the process of evaporation and rainfall infiltration. The numerical results showed that the minimum pore water pressure of the soil slope at the end of evaporation/rainfall decreased gradually and the crack width increased gradually as the crack set closer to the slope; the larger the discharge speed of pore air, the greater the crack width. With the increase in the evaporation rate, the pore water pressure of the soil slope reduced and the crack initiated earlier and became wider. As the infiltration rate increased, the pore water pressure of the soil slope and the crack width increased, but the decreasing duration became shorter. The change of tensile strength had little effect on the pore water pressure, but the development of the crack width changed with evaporation and rainfall infiltration.

scholarly journals Seismic Stability Analysis of Saturated and Unsaturated Soil Slopes Using Permanent Displacement

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Shuai Huang ◽  
Yanju Peng
Keyword(s):  
Pore Water ◽  
Unsaturated Soil ◽  
Calculation Method ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Simple Calculation ◽  
Seismic Stability ◽  
Permanent Displacement ◽  
Soil Slopes

The permanent displacement has been widely used for slope seismic stability in practical engineering; however, the effect of the dynamic pore water pressure on the saturated and unsaturated soil slopes could not be neglected. In this paper, we propose a calculation method of dynamic pore water pressure by the hollow cylinder apparatus (GCTS) which is the most advanced and complicated device in lab testing on soil dynamics. Then, based on the proposed calculation method of dynamic pore water pressure combined with the limit equilibrium and finite element methods, we introduce a simple calculation method of permanent displacement, which avoids solving complex nonlinear equations and greatly simplifies the computational effort. Shaking table test results demonstrate the effectiveness and efficiency of the simple calculation method of permanent displacement, which could rapidly assess the soil slope seismic stability considering the effect of dynamic pore water pressure.

Infiltration characteristics of two instrumented residual soil slopes

2003 ◽  
Vol 40 (5) ◽  
pp. 1012-1032 ◽  
Author(s):  
Illias Tsaparas ◽  
Harianto Rahardjo ◽  
David G Toll ◽  
Eng-Choon Leong
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Measurements ◽  
Residual Soil ◽  
Rainfall Runoff ◽  
Rainfall Events ◽  
Pore Water Pressures ◽  
Soil Slopes ◽  
Pressure Changes

This paper presents the analysis of a 12 month long field study of the infiltration characteristics of two residual soil slopes in Singapore. The field measurements consist of rainfall data, runoff data of natural and simulated rainfall events, and pore-water pressure changes during infiltration at several depths and at several locations on the two slopes. The analysis of the field measurements identifies the total rainfall and the initial pore-water pressures within the two slopes as the controlling parameters for the changes in the pore-water pressures within the slopes during infiltration.Key words: infiltration, rainfall, runoff, pore-water pressure, field measurements.

The Effect of Rainfall Infiltration Time to the Unsaturated Soil Slope Stability

2011 ◽  
Vol 71-78 ◽  
pp. 4864-4867
Author(s):  
Guang Hua Cai ◽  
Hai Jun Lu ◽  
Wei He ◽  
Long Guan ◽  
Wei Qi Xu
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Rainfall Infiltration ◽  
Soil Slope ◽  
Soil Permeability ◽  
Rainfall Condition ◽  
Pressure Changes

Rainfall infiltration is currently one of the important factors in studying the soil-slope stability. By using saturated-unsaturated seepage theory, the traditional limit equilibrium method and so on, analyze the water content and the pore-water pressure changes under the rainfall condition, then analyze the influence mechanism of the slope stability. Through the Seep/W and the Slope/W of the GEO-Slope software, do the numerical simulation of the slope stability under the rainfall condition, to seek the distribution of pore-water pressure on the rainfall situation and the influence of the seepage field from various parameters such as rainfall intensity and the soil permeability coefficient, thus to study the slope stability.

Use of recycled crushed concrete and Secudrain in capillary barriers for slope stabilization

2013 ◽  
Vol 50 (6) ◽  
pp. 662-673 ◽  
Author(s):  
H. Rahardjo ◽  
V.A. Santoso ◽  
E.C. Leong ◽  
Y.S. Ng ◽  
C.P.H. Tam ◽  
...  
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Coarse Grained ◽  
Residual Soil ◽  
Soil Slope ◽  
Capillary Barrier ◽  
Concrete Aggregates ◽  
Crushed Concrete ◽  
Residual Soil Slope

A capillary barrier is a two-layer cover system having distinct hydraulic properties to minimize water infiltration into the underlying soil by utilizing unsaturated soil mechanics principles. In this study, a capillary barrier system was designed as a cover system for a residual soil slope to maintain stability of the slope by minimizing infiltration during heavy rainfalls in the tropics. The capillary barrier system (CBS) was constructed using fine sand as the fine-grained layer and recycled crushed concrete aggregates as the coarse-grained layer. The coarse-grained layer is commonly constructed using gravels or granite chips. However, due to scarcity of aggregates and in consideration of environmental sustainability, recycled crushed concrete aggregates were used as the coarse-grained layer in this project. The suitability of recycled crushed concrete aggregates as a material within the coarse-grained layer of a CBS is subject to the hydraulic property requirement. For comparison, another CBS was constructed using fine sand as the fine-grained layer and a geosynthetic (Secudrain) as the coarse-grained layer. The performance of each constructed CBS on the residual soil slope was monitored using tensiometers installed at different depths — from 0.6 to 1.8 m below the slope surface — and a rainfall gauge mounted on the slope. An adjacent original slope without the CBS was also instrumented using tensiometers and piezometers to investigate the performance and effectiveness of the CBS in reducing rainwater infiltration and maintaining negative pore-water pressures in the slope. Real-time monitoring systems were developed to examine pore-water pressure, rainfall, and groundwater level in the slopes over a 1 year period. Characteristics of pore-water pressure distributions in the residual soil slope under a CBS with recycled crushed concrete aggregates and in the original slope during typical rainfalls are highlighted and compared. The measurement results show that the CBS was effective in minimizing rainwater infiltration and therefore, maintaining stability of the slope.

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