Evaluation Of Landslide Stability And Management Engineering Design Of Nianzhuanggou Motor City In Yan'an

The northwest loess plateau region is one of the most serious landslide area in China,landslide hazards have caused serious damage to industrial and agricultural production,railway and highway traffic,safety of the people and ecological environment in the vast areas of the loess plateau area.The loess landslides with its typical regional characteristics,formed in the bank slope of valleys,bedding slip along the red soil layers or flat sedimentary rock layers have a step-like shape as a large size of the body and are easy to appear landslide revival disaster under the engineering action of old loess landslides.The Motor City landslide at the Nianzhuanggou in Yan'an City belongs to the typical resurgent landslide that has been partially revived due to the excavation of the old loess landslide.Based on the analysis and evaluation of the landslide stability,the study on landslide management design is carried out.The main research results of this paper are as follows,(1)The landslide is a resurrection part of the old loess landslide under the action of artificial engineering.The lower part slides to the bedrock surface which belongs to the holocene loess landslide.The landslide factors are fully developed and the slope deformation during the exploration reaches 0.4 to 0.6mm/d which is in the period of creep change.(2)Using the model of limit equilibrium analysis,the overall stability coefficient of engineering landslide under the natural conditions is 0.999 to 1.041,indicating that the landslide is in an unstable and under-stable state.The residual lower thrust is 489.48 to 701.37 kN/m3 when the safety coefficient is 1.30.The stability coefficient is 0.981 to 1.022 considering the saturation condition,and the landslide is in an unstable and under-stable state(check).(3)Using FLAC3 D calculation model,using ideal elastic-plastic materials,based on the strength reduction method,Mohr-Coulomb which is common in numerical calculation is used to the nonlinear finite element analysis of slopes and obtains the safety coefficient of the slope.The overall stability coefficient of engineering landslide under the natural conditions is 1.000 to 1.040,indicating that the engineering landslide is in an under-stable state.The stability coefficient is 0.980 to 1.020 considering the saturation condition,indicating that the landslide is in an unstable and under-stable state.The conclusions of multiple calculation methods are consistent with qualitative judgments,so the conclusions are used to decorate the management plan.(4)The management plan is recommended in the conditions of adequate consideration of the environmental protection.Plan one,anti-sliding piles are arranged on the first-level platform,the front part is equipped with three seepage blind ditches,masonry stone slope protection are used at the front slope,and the systematic cut-off drains are arranged at the lateral side of the trailing edge.Plan two,the masonry stone retaining wall is set in the front edge of the landslide,the middle platform of the landslide body adopts the micro-piles,and the systematic cut-off drains are arranged at the lateral side of the trailing edge.This paper recommends plan 1 after the compare and selection.