| In China,the distribution of loess area is very vast.It is due to its fragile geological condition,which makes it become the worst-hit areas of geological disasters,all the time.With the development of the western regions and the “One Belt And One Road”,more frequent engineering activities in the loess regions,often cause landslide disasters,which pose a serious threat to people’s life and property,meanwhile seriously restrict the development of regional economy.The mainly research direction of the essay is the mechanism of loess landslide induced by engineering excavation.The paper sets the Yan’an Liu wanjiagou landslide and 9.17 Baqiao landslide as the starting point,bases on the geologic background of loess landslides,expounds damage characteristics and analyzes the causes of the loess landslides induced by engineering excavation.On this basis,it utilizes the centrifugal model test to analyze the deformation and failure process of loess slopes induced by excavation,and plan different partitions of the loess slope.By taking advantage of the numerical simulation technology,through simulating the loess slope under different excavation conditions,it obtains the loess slope stability analysis in every situation.Finally,it summarizes the formation mechanism and failure mode of the loess slope instability induced by excavation.Getting the following conclusions:(1)Analyze the typical cases of the Yan’an Liu wanjiagou landslide and 9.17 Baqiao landslide.Expound the damage characteristics of the loess slope instability induced by excavation.The previous engineering excavation is the main cause of the landslide.(2)Through the centrifugal model test of the loess landslide induced by engineering excavation,it can be learned according to the experimental results:(1)Sort out changes of slope displacement field,analyze the deformation of loess slopes.According to it,plan different partitions of the loess slope,which is divided into sliding zone,deformation influence zone and nor-influence zone;(2)Analyze the origin of cracks in the loess slop,reflect trail-type damage characteristics and the forming process of slip zone.On the basis of the development process of cracks,explain the developing of the loess landsides.(3)By utilizing the numerical simulation technology,simulate the excavation conditions of different altitudes,depths and angles.The results are as following:(1)It has the greatest impact on the pure loess slope by the engineering excavation,while it has relatively little impact on the slope existing ancient soil layers by the engineering excavation.It concludes that in loess slopes,the more ancient soil layers in the slope,the stronger self-stabilization capacity under the effect of excavation unloading;(2)In the same excavation situation,the higher the slope is,the bigger the scope of failure would be,thus causing more serious slope damage.Even in a small excavation condition,the loess sloe will develop a large landslide;(3)From different angles of excavation,when the changing degrees of the stress state and displacement exceed the loess slope stability ability,the slope will happen integral sliding failure.(4)It has three processes in the loess landslides induced by engineering excavation,which respectively are the initial creep stage,accelerating creep stage and failure stage. |
