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| Mechanical mechanism and simulation experiment of the collapse of gully cliff in Yuanmou Dry-Hot Valley |
| Chen Anqiang1,2,3, Zhang Dan1,2,3, Fan Jianrong1, Liu Gangcai1,3 |
| 1. Institute of Mountain Hazards and Environment, Chinese Academy of Science & Ministry of Water Resources, 610041,Chengdu; 2. Graduate University of Chinese Academy of Sciences, 100049, Beijing; 3. Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences, 610041, Chengdu: China |
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Abstract The alternating layered distribution of sand soil and clay soil body creates condition for the occurrence of gully cliff collapses in Yuanmou valley. On the basis of previous studies, the mechanical mechanism of gully cliff collapse under flow lateral erosion was analyzed by the simulation test method. The results showed that the flow shear stresses of different flows were within 1.71-8.55Pa, and they were much larger than the critical shear stress (0.13Pa) of started sand moving. The flow scouring caused the lateral recession of sand layer. The formula of lateral recession distance of sand layer was ΔBs=20.131CtΔt(τ-τc)e-1.3τc/γs+0.0047. The main factor of gully cliff instability was caused by the lateral recession of sand layer. By the simulation test, the overhang soil occurred the rotating collapse (Fsb=0.767<1 when the lateral erosion distance of sand layer was 0.312m. When the overhang soil body appeared the tension fractures of 5, 10, 15, and 20cm, those cracks development also accelerated the instability of overhang soil body.
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Received: 01 December 2011
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