| Wulipo landslide is the studying subject in this paper, basing on field survey, we analysis and describe the accumulation characteristics after failure of landslide and divide each district. Basing on the 1:10000 original topographic map generation by DEM elevation data and the landslide primary state restoring by image information of Google Earth, the formation and evolution mechanism of Wulipo landslide is discussed initially. At the same time, we study the strength characteristics of mudstone in slip zone, including conventional three axis compression test and three axis compression rheological test. At last, we carry out the numerical simulation to analysis the impact of earthquake, intensive rainfall and the properties of mudstone rheological to the landslide, making further study on the formation and evolution mechanism of the landslide, some major conclusions are made as follows:(1) Wulipo landslide is the typical shatter slope after earthquake, instead of occurring in the Wenchuan earthquake, the landslide failed overall in the later continuous intensive rainfall. Through field survey, Wulipo landslide is divided in three regions in planet, slip source region, scraper region and scraper accumulation region;(2)Through the analysis of the influence factors to Wulipo landslide, speculating the type of deformation mechanism is sliding-tension. It started by collective effect of earthquake, intensive rainfall and the properties of mudstone rheological;(3)Through the conventional three axis compression test and three axial compression rheological test on natural and saturated mudstone, we obtained the instantaneous strength parameters and long term strength parameters of mudstone under natural and saturated conditions. Through comparative analysis, we found that long-term shear strength and internal friction angle are reduced by 17.58% and 19.49% compared with the instantaneous shear strength in natural condition, long-term shear strength and internal friction angle are reduced by 39.29% and 35.21% compared with the instantaneous shear strength in saturated condition, the rheological effect of mudstone under saturated condition is more obvious than that under natural condition;(4)Using Burgers component combination model to analyze the linear rheological characteristics of mudstone under natural and saturated conditions, the fitting effect is preferable. At the same time, basing on Burgers component combination model, introducing a damage factor D and the starting time t* from the steady state creep stage to the accelerated creep state, a new nonlinear rheological model of mudstone is established, the applicability of the model is verified basing on the LM algorithm to fitting analysis;(5)Detailed description and comparison of the failure characteristics of mudstone under conventional three axis test and three axis rheological test under natural and saturated conditions are carried out, finding that he failure of mudstone under conventional three axis test and three axial rheological test is shear failure under natural condition, but the failure surface are different. The mudstone is mainly realized by axial compression failure in conventional three axis test in saturated condition, the failure surface is existed but non-through. In three axial compressive rheological test, the failure surface of mudstone is first to produce the splitting failure along the axial direction, and eventually the shear failure along the most dangerous surface under saturated condition;(6) Using the UDEC software to simulate and analyze Wulipo landslide under earthquake effect, the landslide is steady before Wenchuan earthquake, the integrity of rock mass in the landslide was destroyed in the earthquake, the specific performance is that vertical joints are mainly tensile failure and the layer joints are mainly shear failure. And the analysis results show that instead of occurring in the Wenchuan earthquake, but only local collapse failure;(7)Using the Seep module in Geo-studio series software to analyze the effect of the internal flow field under the action of intensive rainfall of Wulipo landslide after Wenchuan earthquake, during the intensive rainfall, the change of the seepage field in the slopes is mainly reflected in the elevation of the groundwater level in the seismic fissure, and the groundwater level in other parts of the slope changes little;(8)Using the Slope module in Geo-studio series software to calculate the stability of Wulipo landslide in three schemes that designed including only considering the effect of intensive rainfall, only considering the rheological properties of mudstone in slip zone and comprehensive considering the effect of intensive rainfall and rheological properties of mudstone. The results show that the failure of Wulipo landslide occurred in considering the intensive rainfall and the rheological properties of mudstone, and concluded that the failure of Wulipo landslide is the comprehensive of earthquake, intensive rainfall and rheological properties of mudstone in slip zone. |
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