Research On The Development Law And Movement Characteristics Of Multi-stage Volcanic Rock Collapse In Extremely Cold Mountain

Volcanic eruption is one of the most spectacular sights in nature.and its related magmatic activities and geological phenomena are the base of the study of volcanic geology.However,the unique geological conditions formed after the volcano erupted are mostly accompanied by the occurrence of volcanic geological disasters,such as collapses and debris flows.Therefore,to explore its relationship with volcanic geological characteristics.The relationship between volcanic geological disasters will help to understand the types,characteristics and distribution laws of disasters,and have certain practical significance for disaster prevention.The Changbai Mountain Tianchi Volcano is the youngest and most dangerous Cenozoic active volcano in China.The Erdaohe Canyon in the northern part of Tianchi is a must-see attraction for both Chinese and foreign tourists,and it is also an area with frequent geological disasters.Therefore,this paper takes Erdaobaihe Canyon in the northern scenic area of Changbai Mountain as the research object,analyzes the development and distribution characteristics and potential failure mode of dangerous rock mass in the study area,and discusses the effect of freeze-thaw cycle on rock quality deterioration and the frost heaving force on dangerous rock mass The effect of stability.Through theoretical analysis,model test and numerical simulation of the three-dimensional movement of the rolling stones,the movement characteristics of the collapsed rolling stones in the study area are analyzed,and the deformation response characteristics of the lining structure under different prevention measures of overhead rock mass are compared.Risk assessment system to evaluate the danger of dangerous rocks in scenic spots.Through the above research,the main results of this paper are as follows:（1）Through detailed on-site investigations,combined with three-dimensional laser scanning and high-density electrical method,etc.,grasp the development and distribution law of volcanic rock collapse in the study area,and summarize the instability model of dangerous rock mass in the study area due to the multi-stage volcanic eruption discontinuity Compressed dangerous rock masses controlled by coarse-faced tuff breccia and primary columnar joints are the main ones.（2）The effects of factors such as lithology,freezing and thawing times,saturated water or not on the degradation of the freeze-thaw cycle of the rock were analyzed through the freeze-thaw cycle test,and through X-ray diffraction test（XRD）,electron microscope scanning test（SEM）,uniaxial The compression test analyzes the deterioration and damage of physical and mechanical properties such as the migration of coarse rock and tuff material components,the expansion of micro-cracks,and the peak strength.（3）Evaluate the stability of dangerous rock masses with different instability modes from the qualitative and quantitative dimensions through the calculation methods of erythroid projection and rock fracture mechanics.In the quantitative evaluation process,combined with the freeze-thaw test results,the frost heave force was introduced as the stress intensity factor to analyze the stability of the dangerous rock mass under four different working conditions such as freeze-thaw.（4）The two-dimensional kinematics theory is used to analyze the whole process of the formation of rockfall due to the instability of dangerous rocks,including the initial movement phase,flight phase,collision phase,rolling phase and sliding phase.Based on the indoor model test,it is clear that the characteristics of the slope cover are the main influencing factors of the rolling stone collision recovery coefficient.At the same time,the regression analysis is used to obtain the empirical formula of the collision recovery coefficient y=0.791-0.162x₁ for the Erdaobaihe Canyon of Changbai Mountain,and it is passed The Rockfall software example verifies the rationality and applicability of the empirical formula,and provides a basis and reference for the calculation of the three-dimensional motion characteristics of the rolling stone.（5）Based on the point cloud data generated by the three-dimensional laser scanning,a three-dimensional model is built,combined with the empirical formulas summarized in the field investigation and model test,and applied to the three-dimensional motion simulation software CRSP-3D to analyze the massive rock instability of four typical slopes The movement path,bounce height and stop range of the rock formed afterwards provide data support for the risk assessment of dangerous rock mass in the study area.（6）Based on the field investigation results and analysis on the basis of 7 kinds of evaluation index,evaluation index factor as the foundation with space multi-level evaluation method（SMCE）construction of changbai mountain scenic area 2 baihe valley north risk assessment system,the risk in the studied area partition,and using ROC curve analysis of the evaluation model of credibility.