Abstract:Daguangbao landslide is the largest landslide triggered by “5•12” Wenchuan earthquake. The exposed sliding zone with a length of 1.8 km and highly ruptured rock mass occurred on the south side of the landslide,which attracted great attention across the world and was a focus in the past 6 years. The engineering geological mapping and exploration in the past made the cataclastic characteristics of rock mass in sliding zone to be well revealed. The sliding zone was found to be bedding on a fault zone of the slope. Because of the strong vertical ground motion near the seismogenic fault,the slope was separated along the bedding fault zone which was the relatively weaker interlayer. Vertical impacting or tamping within the weaker layer occurred leading to the further fragmentation. Mesoscopic analysis of sliding zone confirmed the existence of the earthquake induced fragmentation in sliding zone and revealed the dilation effect in the process of fracture,which was further verified with the physical simulation and PFC numerical simulation. The rock mass fragmentation and dilation of sliding zone were thus concluded to be very significant. Firstly,the further fragmentation and fine grains of the rock mass reduces the friction of sliding zone. Secondly,what is more important,because of the tamping and synchronous dilation within the sliding zone,groundwater will be strongly squeezed into the dilated space,which may stimulate the water hammer with the rapid increase of pore water pressure and the sharp reduction of shear resistance and as a result,causes initiation of the landslide suddenly with high traveling speed.
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HUANG Runqiu,PEI Xiangjun,CUI Shenghua. Cataclastic characteristics and formation mechanism of rock mass in sliding zone of Daguangbao landslide. , 2016, 35(1): 1-15.
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