Abstract
Expansive soil is a kind of clay soil that expands rapidly after being immersed in water and shrinks significantly after losing water. The expansive soil slopes exposed to the atmosphere are in the process of continuous dry and wet cycles and are extremely unstable under the conditions of rainfall. Based on saturated-unsaturated seepage theory, the unsaturated seepage process and humidification process of the expansive soil slope under rainfall were simulated, and a related FORTRAN language program was developed. The effects of matrix suction changes, seepage softening, and moistening expansion during the seepage process were considered. The effects of strength attenuation, seepage softening, and moistening expansion on the overall stability of the expansive soil slope were analyzed. The results show that under the action of rainfall, the failure mode of the expansive soil slope after multiple dry-wet cycles is shallow collapse, and the failure surface is located in the weathered area, which is quite different from the traction landslide of the homogeneous expansive soil slope. After considering the moistening expansion and softening effects, the maximum displacement of the slope increased by an order of magnitude, and the safety factor decreased significantly. The significant increase in the horizontal stress of the lower half slope is the main reason for the landslide. The research results well explain the special tractive and shallow properties of typical expansive soil landslides.
Highlights
Expansive soil is a special soil widely distributed all over the world
Expansibility and strength attenuation are the two most critical factors affecting the stability of expansive soil slopes, but the current research fails to consider the effects of both at the same time
The amount of moistening absorption deformation is calculated based on the change of the humidity field of moistening the slope caused by rainfall, the strain field is updated, and a new stress field
Summary
Expansive soil is a special soil widely distributed all over the world. Expansive soils have been found in more than 40 countries around the world, covering six continents. A lot of research has been carried out on the influence of dry-wet cycle on the strength of expansive soil and the slope stability. Wang Guoli [7] used a centrifugal model test to study the stability of expansive soil slope under the condition of dry and wet cycles. Yin Zongze [8] divided the expansive soil slope into three layers: completely weathered layer, semi-weathered layer, and non-weathered layer He gives the approximate determination method of the strength parameters of each layer but does not consider the influence of the expansibility, so the calculated stability coefficient is too large. Expansibility and strength attenuation are the two most critical factors affecting the stability of expansive soil slopes, but the current research fails to consider the effects of both at the same time.
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