Research On Dynamic Disaster Mechanism And Mitigation Measures Of The High-locality And Long-runout Landslide

High-locality landslide are mainly distributed in the high-mountain gorge areas,western China.It has the features of burst slide,destructive and wide hazard scope.It has seriously imperilled the safety of people-'s lives and property.Thus,strengthening the study of long-runout and dynamic disaster mechanism of the high-locality landslide is important.It could reveal the transformation between potential energy and kinetic energy and develop the movement mechanism.Tacking the Xinmo landslide as an example,based on the field geological survey,satellite images analyses,theoretical derivation,physical model test and numerical simulation,the disaster-forming mechanism,dynamic impact,accumulation,early identification and hazard mitigation measure are analysed.The main results of this research are as follows:(1)Based on the analysis of typical high-position landslide geological disasters at home and abroad,the definition,classification and characteristics of high-locality landslide disasters are summarised.Moreover,the disaster control mechanism of a slippery geological structure is analysed(i.e.,Weak structural belt,Locking section and Freeze-thaw of loess).The mechanism of high position landslide induced by earthquake,rainfall and human engineering activities is analysed.Finally,the chain disaster mode of high-level and long-runout landslide is discussed.(2)By geological field survey,remote sensing image analysis and laboratory test,the engineering geological conditions and the distribution of ancient landslides in the study area are analysed.It is found that the Xinmo landslide stratum is mainly the marble formation of metamorphic sandstone mixed with slate.The shape of the collapse-landslide body presents the“U”type.Fractures are very developed in the mountain ridge.Rock mass was meshed by earthquake and dominant joint cutting.The study shows that the failure of landslide buckling under long-term self-weight and rainfall.The microscopic test results show linear scratches,mineral directional aggregation arrangement and micro-fracture development.These indicate that the sliding body moves violently,and the collision disintegration effect is obvious.(3)Based on the failure equation of curved structure and Hoek-Brown strength criterion,the change trend of critical length of collapsing section is analyzed.According to the principle of peak residual drop,starting speed and running speed of the Xinmo landslide are calculated.According to the principle of potential energy transform,the calculation model of dynamic impact force of the two Xinmo landslides with or without initial velocity is established.Moreover,the influence of gradient and loading volume on dynamic impact force is analyzed.What's more,the stability of the Xinmo old landslide under dynamic impact load is calculated.The result shows that when the loading volume is 100-150×10~4m~3,the accumulation will slide.(4)According to the UAV aerial photograph and digital image recognition technology,the variation law of particle size and fractal number of Xinmo landslide along the landslide movement direction is analysed.The results show that the farther the sliding distance is,the higher the fragmentation degree of the sliding body is.There were accumulation landform characteristics in the frontal area of the landslide,such as accumulation platform,moving ridge and block stone directional arrangement.Using the methods of ensemble empirical mode decomposition(EEMD)and time-frequency analysis,the study displays the seismic signal of Xinmo landslide is dominated by low frequency.Based on the geological characteristics and dynamic analysis,a dynamic disaster zoning method for Xinmo landslide is proposed:rapid occurrence area,impact loading area,fragmentation migration area and scattered accumulation area.(5)Landslide dynamic methods mainly include experience method,continuum method and discrete element method.These methods simulate the entire process of the Xinmo landslide to obtain the speed,thickness and movement law of the typical position.The discrete element method is more suitable for simulating kinematic process(.i.e.,impact load,old landslide instability,avalanche).Based on the physical model test method,the effects of particle size,slope and mass on the velocity and accumulation range of landslide were discussed.What's more,the motion models of the rockslide debris are established.(6)By the detailed geological survey,the geological indicators for early identification of high-positin landslide are proposed,including slope structure,rock type,topography and so on.What is more,the early identification method is improved.This paper presents an early recognition method based on the easy-sliding geological structure and space remote sensing monitoring of"Space-Air-Ground"integration,coupled with the analysis of the easy-sliding and collapse geological strength index,which can effectively guide the analysis of the evolution process of the high-level landslide from disaster preparation to imminent disaster,making it one of the important methods for disaster prevention and reduction of the high-level landslide.