| Lvliang City is located in the west of Shanxi Province,located in the Loe ss Plateau in the west of Shanxi Province.Most areas of the city are covered with different thickness of loess,the hilly gullies are vertical and horizontal,th e internal geological environment is fragile,geological disasters occur frequently,especially loess landslides.According to the investigation,221 loess landslides have occurred in Lvliang City,including 172 small loess landslides,36 mediu m loess landslides,13 large loess landslides,and no super-large and giant land slides.Potential disasters in the area seriously threaten the lives and property o f the local people.The root causes,trigger factors and early warning of these disasters have become a major concern of the relevant departments.Based on the abundant investigation data of loess landslide,this paper find s out the location,quantity and type of landslide in Lvliang City,analyzes the patial and temporal distribution characteristics of landslide,and carries out the study on the vulnerability zoning of loess landslide in the study area.On this basis,in order to effectively formulate the single landslide prevention and contr ol policies,further summarize the typical loess landslide types,carry out the a nalysis of main controlling factors and disaster-forming models of typical loess landslides,based on unsaturated soil theory,in the early rainfall,The influenc e degree of daily rainfall on landslide stability was numerically simulated and analyzed.Based on the calculated results,a loess landslide early warning mode l was constructed to provide technical support for disaster prevention and mitig ation of loess landslides.The following conclusions have been reached:(1)The landslides in the study area are characterized by wide distribution,large number and non-uniformity,among which Liulin County and Jiaokou Cou nty are the majority.The spatial distribution is along different landforms,fold and fault blocks are divided into regions,disaster points are linearly distributed along roads,railways and rivers,and local distribution of disaster points is con centrated.From June to August of each year,the landslides occurred during th e period of high incidence,especially in July to August of rainfall concentration,accounting for about 75% of the total number of disasters.(2)The distribution of landslides is closely related to the topography and landform.The landslides are especially developed in the area of 800 ~ 1300 m elevation,5 ~ 25 °slope,sunny slope direction,concave slope and loess beam area.Landslide also has a good correspondence with stratigraphic lithology veg etation index and human engineering activities.(3)The degree of vulnerability of landslides in the study area is divided i nto four levels: high-vulnerability area,middle-prone area,low-vulnerability area and non-occurrence-prone area.Among them,the high-risk area accounts for 23.26% of the total area of Luliang City,including 115 landslide disaster points,accounting for 51.8% of the total disaster proportion,and the middle-prone are a accounting for 21.74% of the total area of Luliang City.85 landslide disaster points account for 38.28 percent of the total disaster,44.42 percent of Luliang City's area in low-risk areas,9 percent of the disaster proportion of 20 landsli de disaster points,and 10.58 percent of Luliang City's area in less prone areas.It contains 1 landslide point,accounting for 0.45% of the disaster.The high-ris k area and the middle-prone area account for 45% of the total area of Luliang City,and the disaster points of the two regions account for 90.08% of the tota l disaster points.This indicates that the structure of the vulnerable zone is reas onable.(4)The loess landslide in Lvliang city is divided into three types: Q3 sin gle layer sliding,Q3-Q2 composite stratum structural layer sliding and loess-mu dstone interface sliding.The landslide sliding in a single layer is mainly relate d to its own slope height.The higher the slope body,the more prone to the d isaster of slope.Rainstorm is often the dominant factor of this kind of landslid e.The landslides on the loess-mudstone interface are often formed in the high and steep slope where the occurrence of the bedrock is smooth,with the chara cteristics of large sliding potential energy,low sliding speed and small slip dist ance,and the landslide has the characteristics of large sliding potential,low sli ding speed and small slip distance.Torrential rain is often the leading factor to induce such landslides.Most landslides in the structural layer of Q3-Q2 interfa ce composite strata have the characteristics of steep slope and high slope.Rain storm and engineering activities are often the inducing factors of this kind of l andslide.(5)Based on numerical simulation and field investigation,the evolution process,disaster formation model and main control factors of different types of l andslides are analyzed.The results show that the loess landslides in the study area are formed under the coupling of human engineering activities and rainfal l..(6)On the basis of analyzing the characteristics of deformation and destru ction,the formation mechanism and the main control factors of the loess landsl ide in Puguicun,an early warning model of rainfall-rainfall in loess slope is es tablished,which is based on the analysis of the deformation and failure charact eristics,the formation mechanism and the main control factors.The model is v erified by the rainfall data of landslide sliding and the monitoring data obtaine d in recent years.The results show that the model is consistent with the actual situation and has a certain applicability. |
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