Slip Surface Identification And Stability Study Of Jinjiling Landslid

The complex geological conditions in the Three Gorges Reservoir area and the special regional meteorological and hydrological conditions make it very easy to induce the generation of new landslides and the resurrection of ancient landslides under the conditions of human engineering activities and heavy rainfall.Based on this,this paper takes the Jinji Ridge landslide in Longshui Village,Jiangdong Group,Wushan County New District as an example,which is obviously deformed after heavy rainfall,and obtains the location and morphology of Jinjiling landslide slip surface through site investigation,high-density electrical method,borehole full-wall imaging method and deep obliquity measurement method,based on which a correct engineering geological profile is drawn,and initially concludes the main influencing factors of Jinjiling landslide development and the This will provide a technical basis for the subsequent study of landslide stability.In order to further identify the genesis mechanism of the landslide,the stability of the landslide under different working conditions was analyzed by using the limit equilibrium method and numerical simulation method,in which a finite element model was established to analyze the stress,strain field,displacement field and seepage field of the landslide by numerical simulation method,and compared with the actual monitoring displacement data to comprehensively determine the genesis mechanism of the Jinjiling landslide.The specific research contents and the results obtained are as follows:（1）High-density electrical method,borehole full-wall imaging method,deep obliquity measurement and other technical methods were used to determine the specific location of the potential sliding surface.The geological interpretation shows that the Jinjiling landslide is a mixed rock-soil,water-bearing landslide,and the sliding surface is located at the boundary line between T₂b¹marl and T₂b²mudstone;the deep displacement monitoring reveals that the landslide is a shallow surface soil body sliding,and the sliding surface is consistent with the location of the sliding surface from the geological interpretation;the horizontal displacement monitoring shows that the deformation rate of the shallow distributed Hou Bang landslide and Pan Jia Ling landslide is fast and strong.The leading edge of the Jinjiiling landslide slides along the intersection of mudstone and marl,and the middle part shears from the interior of mudstone,while the trailing edge slides along the rock-soil interface or the interior of soil,so the slide bed of the Jinjiling landslide is mainly T₂b¹marl and T₂b²mudstone;while the Pan Jia Ling landslide and Hou Bang landslide are soil landslides,whose sliding surface is the rock-soil interface and the slide bed is T₂b²mudstone.At the same time,the main influencing factors for the development of the Jinjiling landslide and the genesis mechanism of this landslide are initially derived.（2）The stability analysis of the Jinjiling landslide was carried out using the limit equilibrium method and the numerical simulation method,and the similarities and differences between the two analysis methods in the process of landslide analysis were compared.The stability coefficients obtained from the numerical simulation method are higher than those obtained from the limit equilibrium method by about 4.2%on average under the status quo condition,about 5.4%higher than those obtained from the limit equilibrium method under the drained groundwater condition,and about 4.8%higher than those obtained from the limit equilibrium method under the heavy rainfall condition.The stability coefficients derived in the case of heavy rainfall are on average about 4.8%higher than those derived from the limit equilibrium method.By comparing the measured monitoring data and numerical simulation results,it was found that the cumulative displacement of the actual monitoring gradually approached the numerical simulation,indicating a trend of further sliding of the landslide.The position and shape of the potential slip surface calculated by the finite element strength reduction method are basically consistent with the position and shape of the real slip surface.When there are multiple potential shear outlets and slip surfaces,the finite element strength reduction method is recommended for analysis.（3）The topography of the Jinjiling landslide is chair-like,the topography of multiple gullies,the loose lithological structure of the strata,and the local oblique geological structure are the physical sources and site conditions for the formation of the landslide,and the"6·18"heavy rainstorm and human engineering activities are the external triggering factors for the formation of the landslide.The high and steep prominence formed by the construction has destroyed the stability of the landslide itself and further reduced the stability of the landslide,and the coupled rainstorm conditions are the triggering factors for the destabilization of the Jinjiling landslide.（4）The Jinjiiling landslide as a whole is in the unstable～basically stable state under the current situation;it is in the unstable～basically stable state under the drained groundwater situation;it is in an unstable to unstable state under the heavy rainfall situation,and destabilization damage may occur;among them,the Panjialing soil landslide and Hou Bang soil landslide are strongly deformed and damaged.The Jinjiling landslide belongs to the nudging slip and shallow soil secondary slip deformation,and the deformation and damage trend from local to overall and from superficial to deep;the numerical simulation results further verify that the relevant drainage management measures are reliable and effective.It is recommended to pay close attention to the"water management"measures,especially for landslides with shallow water table and abundant surface water,and to strengthen surface drainage to prevent surface water infiltration,strengthen continuous monitoring of landslides in the later stage,and adjust the measures in time according to the situation.