The Forming Mechanism And Process Study And Risk Assessment On The Typical Geological Hazards In Zizhou County

Zizhou County was located in the Loess Plateau,The Loess terrain and ravined aremainly geographic;With loess loose structure, vertical joint development,and poor vegetationcover,geological environment is fragile,landslides and other geological disasters are welldeveloped,posed a great threat to people’s life and property safely of Zizhou County.In orderto reasonable identify and evaluate the impact of geological hazards to life and property scale,need to analyze the conditions of geological disasters, the mechanism and the process andmake the necessary risk assessments.Based on the detailed investigation of geological disasters of the study area,analyzes ofthe natural geographical and geological envirnment conditions;the formation conditions of thegeological disaster;the formation mechanism and the process of the typical geologicaldisaster;and the risk assessment of the typical geological disaster,Finally puts forward theacceptable level of risk management measures.Get the major findings as below:(1)Analyze the conditions of geological hazards of the study area, the system summarizethe formation conditions and the basic geological disasters caused by conditions of study air.Basic conditions include topography, lithology and rock structure,that the topography is themain control function,Controlled by topography and geomorphology of geological disasterare303, accounting for75%of the total number of geological disasters;trigger conditionsincluding water and human engineering activities,that the latter is the main triggerfacto,caused by human engineering activities are237,58.7%of the total;(2)Using finite element software Geo-studio,five original slope models are restoredbefore geological disaster being happened,calculating the stress、strain and the horizontaldisplacement,analyzing its formation mechanism.The maximum shear stress and shear strainof the Landslide are appearing in the slope toe and stratigraphic boundaries,the horizontaldisplacement focusing on the landslide, and decreasing from top to the bottom gradually;thetensile stress appears on the upper slope of the Collapses,and the x direction displacementincreasing gradually in-outward;So is tensile stress of the unstable slope，whose tensile strainand the horizontal displacement increasing along the x axis;(3)Using the discrete element2d-Block simulaing the formation process of geological disasters,the Landslide is divided into creep stage, sliding and accumulation phase; theCollapse being divided into slope cracking stage,dangerous rock mass damage stage,collapsebody accumulation stage;Unstable slope being divided into stages of creep, destruction andaccumulation phase.(4)Three typical are selected to the geological hazards risk assessment in the studyarea.Based on the Monte Carlo algorithm to the calculate the failure probability of theShiPanGouLandslide is P(L)=8.9%,the probability of reaching to the hazard-affected body forthe P(T:L)=1.0,the probability of risk for P(LOL)=0.031which belongs to the unacceptablerisk;NanFengShangCollapse,whose P(L)=20.98%,P(T:L)=1.0,P(LOL)=0.052,belongs to theunacceptable risk;HongLongMaoUnstableSlope,whose P(L)=47.82%,P(T:L)=0.7,P(LOL)=0.117,belongs to the unacceptable risk.