| On October 14,2019,at about 16:00 p.m.,a gently dipping soil landslide induced by lateral recharge of groundwater from an alluvial ditch occurred in Zhenning County,Anshun City.Due to the special geographical conditions,there are two seasonal alluvial ditches on both sides of the slope body,and the joint fissures are developed in the ditch,and the rock-soil contact surface is locally visible,and the landslide cannot occur under conventional conditions.In order to study the formation mechanism of landslide,this paper takes Xuhuang landslide as the research object and starts the master’s thesis research.Based on the collection of previous research data and field investigation,the regional geological survey and hydrogeological survey are conducted on Xuhuang,and the deformation and damage characteristics and formation mechanism of Xuhuang landslide are systematically studied by using engineering geological analysis method,field refinement survey and historical deformation monitoring,numerical simulation and other methods.The main results and understanding of the research are presented.The main results and understanding of the research are summarized as follows:(1)Xu desolate landslide planform is nearly tongue-shaped,south east high north west low,the back edge of the slope body for the boundary,the front edge of the construction of residential buildings led to shear exit is not easily identified,located between two seasonal drains,deformation characteristics are more obvious,mainly fissures,arc-shaped spreading,visible depth,fissure width of a few centimeters to tens of centimeters,extending a few meters to tens of meters.Landslide main slip direction337°,the volume of about 1.22×10~5m~3,landslide scale medium-sized.(2)According to the morphological characteristics of the landslide and the deformation and damage characteristics,the Xuhuangli landslide is divided into the initiation area and the traction area,and it is known that groundwater is the main influencing factor of landslide initiation.The construction of the residential houses at the foot of the slope and the loading of the road lead to the obstruction of the groundwater transport channel in the slope,and the groundwater is silted up inside the slope body Yonggao,and the temporary pressure bearing occurs at the foot of the slope and the collapse and damage occurs.(3)Based on the SBAS-In SAR technique of permanent scatterer,during the monitoring time period from January 1,2017 to December 31,2021,the slope deformation is obvious,mainly concentrated in the front edge,middle and rear of the landslide and both sides of the wash,with an average surface deformation rate of-9 to8mm/a and a maximum settlement rate of 9mm/a.Taking the landslide occurrence time as the node,the time series deformation analysis shows that The difference of slope deformation before and after the occurrence is large.(4)Combined with the numerical simulation results,the formation of Xuhuang landslide mainly goes through two stages,one is in the initiation area by groundwater bearing pressure plays a major role,hydrostatic pressure and super pore water pressure plays a propulsive role in the stress concentration stage,the foot of the slope first collapse damage,the back slide front edge of the hollow;the second is with the lateral gully continuously recharge groundwater,the slope body potential slip surface is softened,followed by downward traction sliding,deformation damage mode for creep slip-pull crack.(5)For the calculation of landslide stability under the conditions of lateral recharge groundwater in the flushing ditch,the form of water pressure distribution at the sliding surface of different pressure-bearing water levels should be taken into consideration in the calculation process.(6)The stability of slopes with pressurized water is sensitive to the pressurized water level,especially in the season of continuous rainfall,the pressurized water level will be raised due to the blockage of the foot of the slope.In the prevention and control,attention should be paid to keep the seepage section of the front edge of the slope unobstructed,and at the same time,attention should be paid to reduce or stop the lateral recharge of groundwater from the cracks and gullies at the back edge to reduce the pore pressure of the slippery surface and reduce the influence of rainfall on the stability of the slope. |
