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| MICROSCOPIC OBSERVATION AND ANALYSIS OF RING SHEAR SURFACE OF SLIP ZONE SOIL |
| LIU Dong1，2，CHEN Xiaoping1，2 |
(1. College of Science and Engineering，Jinan University，Guangzhou，Guangdong 510632，China；
2. Key Laboratory of Disaster Forecast and Control in Engineering，Ministry of Education，Jinan University，Guangzhou，Guangdong 510632，China) |
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Abstract Residual strength of slip zone soil is the major concern of slope engineering. There is a close relation between microstructure of the shear surface and the strength. Ring shear tests are performed on the clay samples (containing sand) that were obtained from an ancient landslide slip zone. The scanning electron microscope is used to analyze microstructure of shear surface and its relationship with strength. Unlike most clay，the shear strength of the investigated slip zone soils exhibits a slight strain-softening，and increasing coarse fraction significantly influences the post-peak strength. Micro characteristics of shear surface show that the shearing process resulted in directional arrangement of particle and microstructure change，followed by coarse particles broken，void ratio increased and particle shape narrowed. Besides，fractal study of the particle by the perimeter-area method reveals that the particle form has a strong fractal feature，suggesting a good negative linear correlation with residual strength.
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Received: 02 May 2013
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2013, Vol. 32 
