Laboratory and Field Testing Study on Shear Strength of Soil Slopes

Based on a practical landslide engineering ,eight horizontal push-shear tests in situ and four teams of repetitive direct shear tests in laboratory were done in order to study the effects of water content on the parameters of shear strength of soil in slide zone and the difference between the peak strength and residual strength. The results show that the progressive slopes have enough time to form a sliding surface so that the stability of this kind of slopes depends on the residual strength, not the peak strength of soil in slide zone. And the results also indicate that the increasing of water content in the soil causes significant decrease of shear strength of soil, which is adverse to the stability of slopes. With the water content increasing, the peak strength also reduces and the shear deformation increases. The horizontal push-shear test in situ can make the stress paths certain according to practical engineering requirement ,and be done under the state of the original structure and water content of soil, which makes it to be a more reasonable , effective and reliable method comparing with the direct shear test in the laboratory.