Study On Deformation And Failure Mechanism Of Slope Driven By Karst Groundwater

In recent years,the slope instability caused by high groundwater pressure is increasing,which brings great hidden danger to the safety of people's life and property.According to the research on landslide induced by high groundwater pressure,it is generally believed that high groundwater pressure has a great influence on the destruction of landslide.For the discussion of the source of high groundwater pressure,many studies say that it is caused by surface rainfall infiltration.However,in carbonate rock area,karst is developed in the interior of the slope,and the high water pressure comes from the interior of the slope.For example,Yanxigou landslide and Yanbantan landslide have the following common characteristics: the landslide is a bedding slope,the lower bedrock surface is carbonate rock,the permeability of the upper sliding mass is relatively weak,the karst fissures are developed on the sliding surface,the groundwater is distributed in veins inside the slope,converges on the sliding surface,and is distributed in a plane on the sliding surface,with good recharge conditions,The special stratum structure makes the slope have the geological conditions of forming high water pressure.In extreme rainstorm or continuous rainfall,the groundwater level in the karst channel rises rapidly,which makes it easier to form high water pressure faster and causes more serious damage.Therefore,through geological analysis,model test and numerical simulation,this paper analyzes the deformation and failure characteristics,inducing factors and deformation and failure mechanism of karst slope driven by high pressure water head,and discusses the relationship between confined water and slope stability.The main achievements of this paper are as follows(1)According to the field geological survey,the recharge,runoff and discharge conditions of karst groundwater in landslide area are mastered.According to the field situation and investigation,it is known that when the slope is damaged,a large amount of sewage gushes out from the front edge.When the landslide is damaged,the toe of the slope first "crumples",and the front edge of the rear sliding mass is empty,and traction sliding occurs one after another.(2)Through the indoor physical simulation,it is concluded that the deep sliding failure of the slope occurs under the combined action of the hydrostatic pressure produced by the groundwater on the back edge of the slope and the uplift pressure produced by the bottom confined water;The shallow circular slip occurs under the seepage pressure of groundwater on the slope;Under the uplift pressure of groundwater on the bottom of the basement,the toe of the slope will collapse.(3)Through indoor physical simulation,the deformation and failure process and influencing factors of slope under different failure modes are obtained.(4)By using the limit equilibrium method,the stability of the slope is calculated under natural conditions,and it is concluded that the slope is stable;Under the condition of confined water,the stability of the slope is calculated when the confined water level is greater than or equal to the landslide trailing edge,and the critical water head is obtained when the slope is damaged.(5)Taking Yanbantan landslide as an example,seep / W module is used to analyze the distribution law of pore pressure of confined water on the sliding surface under the condition of water head change and whether the front edge of permeable layer is blocked or not.The influence of pore pressure of confined water on slope stability is analyzed by numerical method.