Study On Failure Precursor And Damage Transport Mechanism Of Fluidized Landslide

The Wenchuan earthquake has caused a lot of collapses,landslides and other disasters which have the features of large number,wide distribution,the extent of the damage because of strong damage ability in the southwest mountain area and it has formed large blocks,fine clastic materials which often accumulate in the channel,which cause two landslide and debris flow under the rainfall recharge and river recharge.In this paper,Wenjiagou accumulation of loose material selected for the study after the earthquake,and mainly through flume physical simulation experiments were carried out to study on failure precursor and damage transport mechanism of fluidized landslide and to provide some experience for future research.The loose bodies were stacked body tri-axial tests,permeability measurement test,settlement test and porosity measurement to understand their physical and mechanical properties of the material and considering the effect of different area and different fine content basin on the loose accumulation body.Draw the following conclusions:(1)The fluidized landslide mainly through the following stages Under the conditions of rainfall.(a)Because of the infiltration of rainwater and the upper soil initial collapse,the lower soil will be made compacted under rainfall condition.(b)With the increase of rainfall time,there will be a slight shear in the saturated region of the loose deposits.(c)The excess pore water pressure caused by the compression shear zone and then causing the rapid shear to form the fluidized landslide.(2)For the fluidized landslide,the pore water pressure rises slowly before landslide slipping and water level will maintain a stable stage in the soil for the rise in rainfall or trailing groundwater.Early in the development,soil internal displacement meter monitoring found displacement has a small change but large displacement mainly occurred in the sliding regime the detailed flow stage,and large displacement mainly occurred in the sliding stage and sliding stage mainly experienced acceleration,uniform speed,deceleration stage,the acceleration change is relatively large.(3)We found both vibration signals in sliding will change significantly by monitoring the microseismic signals and vibration signal mainly concentrated in the stage of IMF1.We can see the internal structure readjustment of the landslide through the HHT conversion,especially after water into the flume and before sliding along with the development of time signal is more and more obvious by acoustic emission can be found.We also found the fine particle migration in coarse particles through particle size analysis of each part of the water flume through the test.(4)For the destruction process of effective rainfall area and different fine content can be seen in the rainfall experiment,the effective rainfall area of loose deposits have no impact for fine content is 0%.When the fine content is over 16% retrogressive sliding occurred in small effective rainfall area and then into the bulk flow type and sliding.The landslide performed overall liquefaction damage when the fine content is over 8% at large effective area(two cases).The first performance of erosion of slope surface,and then into the liquefaction damage when the fine content over 25%.The results show that the fine particle content and the drainage area have some influence on the fluidized landslide.(5)Fluidized landslide start time decrease and then increase with the increase of fine particle content and the shortest time is 16%.The sliding distance is increased with the increase of fine particle content and the effective rainfall area is greater,more far away from the corresponding sliding.The fine content of 16% is maximum in the toe volume decline accumulation.(6)At the same time position of super pore water pressure value of fuidized landslide,can see: the fine content and effective rainfall area is larger,the excess pore water pressure is greater.The high frequency part of the vibration signal decreases with the increase of the content of fine particles and the larger the effective rainfall area,the greater the vibration energy.(7)The effect of fine content liquefaction of loose accumulation body is not monotonous: loose deposits can not slide when no fine.The fine particle content mainly play the role of lubrication and will promote the increase of pore water pressure when the fine content is small and will easily produce fluidized landslide.The fine particle content play a major role of cementation when the fine content exceeds a certain value and easily occur debris flow.