Study On The Mechanism Of Reactivation Of Old Landslide By Concentrated Seepage

Loess landslide is the most common geological hazard in the loess distribution area of northwest China.The analysis and stability evaluation of landslide formation is a very important subject in the study of geological hazards in loess area.The loess distribution area in northwest China is the largest loess accumulation area in the world,and it is also the largest arid and semiarid climate zone in China.Influenced by climate,local residents in order to ensure the production and living water needs people to build reservoir impoundment,when reservoir built on the slope,its use in the process of concentration produced by the drain water seepage is bound to affect the slope,might cause the loess landslide or induce geological disasters,such as old landslide revival.So choose typical landslides in the area for centralized water seepage old landslide mechanism research,the results can provide the basis for the landslide governance design directly,but also for the similar loess arid areas due to the mechanism of the effect of concentrated water seepage on the old loess landslides after the resurrection research and management to provide the reference.The lane county in Gansu province township of Beishan landslide as the research object,through field investigation,engineering geological surveying and mapping,engineering geologic survey,indoor test and other methods to determine the engineering geological conditions,the area of landslide deformation characteristics and the landslide rock mass physical and mechanical properties.On this basis,adopt Geostudio SEEP/W module of finite element analysis software,establishing two-dimensional lane township of beishan landslide concentrated water seepage seepage analysis model,and analysis the simulation results,after using the software of the SLOPE/W module and the SIGMA/W module coupled to the results,analysis of landslide stability and the change of displacement,stress and strain.The following knowledge is mainly obtained:(1)Concentrated water seepage is formed in the saturated zone around the sink hole,and the saturated zone extends along the sliding surface,and the transverse two water holes have a penetrating tendency,so that the weak zone expands from the sink hole to the surrounding area.(2)The concentrated water penetration increased the weight of soil,thereby increasing the down force,reduces the soil shear strength and smooth surface friction,which reduces the sliding resistance,with the increase of while water seepage,landslide stability continue to reduce,when the water permeates to the old sliding surface,the stability coefficient of the landslide increases and the state of the landslide gradually becomes unstable.When the sliding force is greater than the anti-sliding force,the landslide deforms and damages.(3)The concentration of water seepage increases the horizontal displacement,stress and strain of the old landslide,and the stress and strain increase at the bottom of the sink hole is large,which becomes the weak zone,and the displacement of the top soil mass increases greatly.