Stability analysis considering the distribution and strength of the fissures for expansive soil slope

Shanxiong CHEN¹; Zhangjun DAI¹

¹ Institute of Rock and Soil Mechanics, Chinese Academy of Sciences

Baixar PDF doi:10.20906/CPS/CB-09-0061

Resumo

The stability of expansive soil slope is different from that of conventional clay slope. For many gradual slopes, if calculated through the conventional slope stability analysis method, they should be absolutely stable, but in fact the landslides happened. Fissure is one of the most typical engineering geological characteristics of expansive soil, and it is the key factor to affect the stability of the slope. Usually, the expansive soil slope with fissure structure is regarded as homogeneous. The effect of fissures is reflected by decreasing the strength parameters. This cannot be objective to reflect the characteristics of expansive soil fissures. At the same time, even if the strength parameters used in the calculation are the lowest strength on the fissure surface, for the actual slope, it is correct only when the sliding surface is located in the fissure surface. To complement the limitations of existing expansive soil slope stability analysis method, in which soil structure, especially fissure surface and weak interlayer are generalized, a method is found that take the slope as a combination of homogeneous soil, fissures with filling soils and tension fissures. Based on the investigation of a large number of landslides in the middle route of the South-to-North Water Transfer Project in China, take the spatial information such as height, angle, thickness and length of typical controlling fissure obtained from the site survey into the slope model, mainly including the vertical fissures in the surface soil and the filling fissures of clay minerals in the slope, to establish the geometric model of slope. Then, on the basis of triaxial tests and field large direct shear tests, take the strength parameters of the expansive soil and the fissure surface into account, establish a geological model of expansive soil slope with real fissures. Equilibrium methods, such as Janbu, Spencer and Morgenstern in program Slide, which meet compartmentalization between the forces and torque balance and are suitable for line slidin

Palavras-chave: Expansive soil; Slope; Fissure; Stability analysis; Sliding surface