Informatics Publishing Limited

Xiaohua Qin ¹, Dongsheng Liu ², Qianghui Song ³

Affiliations
1 Department of Civil Engineering, Logistical Engineering University, Chongqing-401311, CN
2 Chongqing Bureau of Geology and Minerals Exploration, Chongqing-400071, CN
3 Chongqing Key Laboratory of Geomechanics & Geoenvironmental Protection, Chongqing-401311, CN

Abstract

Soil-water characteristic curve (SWCC) is a very important curve on reflecting mechanics characteristics of unsaturated soil, and plays an important role in researching the hydraulic and mechanical properties of unsaturated soil. To study the soil-water characteristic curve of loess, the value of air-entry suction and residual saturation of undisturbed and remoulded loess were defined based on Van Genuchten model of unsaturated soil, and the tests of soil-water characteristic curve about unsaturated loess were carried out. The variation of soil-water characteristic curve of unsaturated loess and the differences between undisturbed and remoulded loess were analyzed within the control range of suction, and the Van Genuchten model parameters and expressions were received about undisturbed and remoulded loess. The curves of Van Genuchten model about undisturbed and remoulded loess were acquired based on Van Genuchten model expression. At the same time, the results were used to calculate the seepage field of loess slope and the variation of stability before or after rainfall were acquired based on ABAQUS and strength reduction method.

Keywords

Loess, Soil-Water Characteristic Curve, Model, Saturation, Suction, Slope.

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Xiaohua Qin ¹, Dongsheng Liu ², Qianghui Song ³, Runze Wu ¹, Xu Wang ¹

Affiliations
1 Department of Civil Engineering, Logistical Engineering University, Chongqing-401311, CN
2 Chongqing Bureau of Geology and Minerals Exploration, Chongqing-400071, CN
3 Chongqing Key Laboratory of Geomechanics & Geoenvironmental Protection, Chongqing-401311, CN

Abstract

Landslide is a major natural disaster, and large number of landslide disasters show that rainfall infiltration is a main factor to induce instability for unsaturated soil slope. To explore the failure mechanism of soil slope under extreme rainfall, the influence of rainfall infiltration for soil slope’s saturation, pore water pressure and displacement are analyzed based on fluid-structure coupling and theory of unsaturated soil mechanics under different extreme rainfall conditions. The results show that: (1) It has same rainfall discharge and rainfall duration for the four kinds of rainfall patterns, but they have different space-time effect on soil slope’s saturation, pore water pressure and displacement. (2) The rainfall pattern has large impact on slope’s displacement, and gradually increasing rainfall has most effective for slope’s displacement than other rainfall patterns after rainfall last 48 h, followed by first increasing and then decreasing rainfall after the first type, the third is gradually decreasing rainfall, and the least is stability rainfall. (3) Different rainfall patterns have different danger points during rainfall, but it occurs at the time that when rainfall intensity up to the maximum. According to the paper, gradually decreasing rainfall has most impact on slope’s stability at early-term of rainfall, first increasing and then decreasing rainfall has most impact on slope’s stability at medium-term of rainfall, and gradually increasing rainfall has most impact at last-term of rainfall.

Keywords

Soil Slope, Failure Mechanism, Extreme Rainfall, Fluid-Structure Coupling, Stability.

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