| Rockfall disaster is a common geological disaster in China,especially in some mountainous provinces,and it is more frequent,which can not be ignored.Before the rockfall,it was connected with the parent slope in the form of dangerous rock mass.Because of the irregular shape,complex distribution and uncertainty of dangerous rock mass,it has always been a difficult problem in engineering practice to predict the stability of dangerous rock mass,the impact caused by falling,the risk rating of rockfall area and what effective measures should be taken.Therefore,this paper takes the dangerous rock mass of the natural slope at the waterfall in Qianzhangyan Scenic Area as the research object,and on the basis of on-the-spot investigation,data collection and analysis,combined with the characteristics and influencing factors of the dangerous rock mass,uses the methods of numerical simulation and drone modeling to evaluate the risk level of the research area,and puts forward some targeted prevention measures and suggestions.The main research contents and achievements of this paper are as follows:(1)Through on-the-spot investigation,a three-dimensional real-life model is established by using UAV tilt photography technology.By analyzing and calculating the point information of the 3D model,the structural plane data are obtained,and the special geological environment and structural conditions of the area where the current dangerous rock engineering geology is developed are found out.Combined with stereographic projection analysis,the stability of typical dangerous rock mass is evaluated.Through stability judgment,it is found that dangerous rock mass is in an unstable state,and it is easy to collapse and form falling rocks.(2)Taking the sections of five typical dangerous rock masses in the unstable state of W1～W5 in the study area as the calculation sections,using Rocfall software,combined with the data such as the position of dangerous rock mass,the longitudinal section and volume of the mountain at the point measured from the three-dimensional real-life model,the movement parameters such as movement trajectory,impact kinetic energy,movement speed,bouncing elevation,etc.during caving are analyzed.The results show that the dangerous rock masses W1,W2,W4 and W5 are likely to enter the lower footpath when they fall unsteadily,which has a great potential safety hazard,while W3 is less likely to enter the footpath when it collapses.(3)17 kinds of rockfall risk assessment methods at home and abroad are selected,and their advantages and adaptability are analyzed and compared,and the RRRS risk assessment method suitable for natural slope risk assessment is selected.The method is improved,that is,five parameters,such as rock size,typhoon,weathering,protective and remedial measures and the degree of obstacle blocking the line of sight,and two parameters,such as removing karst and earthquake hazard,are added.Aiming at the problem of strong subjectivity of analytic hierarchy process(AHP),the method of determining weight based on literature analysis and factor frequency is improved,and finally it is concluded that the risk level of the study area is high.(4)According to the evaluation grade,the corresponding preventive measures combining active(bolts and anchors)and passive(protective net,wire rope,fence and removing unstable stones)are put forward.At the same time,the special factor that the study area is a scenic spot is fully considered,and the method of "avoiding if you can,not avoiding when you can" is put forward for 17 dangerous rocks and dangerous rock zones in the study area.The research results of this paper have important reference significance for the field investigation,stability analysis,risk assessment and prevention and treatment of dangerous rock mass similar to high and steep natural slopes. |
PDF Full Text Request