Stability Analysis And Intelligent Monitoring And Treatment Of Dangerous Rock Collapse

Dangerous rock collapse is a common geotechnical hazard.Because of the irregularity of the shape and boundary conditions of dangerous rock,how to accurately and quantitatively analyze and evaluate the stability of dangerous rock collapse has always been a difficult problem in preventing geotechnical hazards.Taking the dangerous rock of high rock slope at the entrance of Xincai Tunnel in Shenzhen as an example,through the site engineering geological survey and data collection of the slope,the stability of the collapse of dangerous rock is analyzed by means of stereographic projection analysis,theoretical calculation of the movement path of dangerous rock falling,simulation of Rocfall falling path,etc.The active protection of dangerous rock slope is proposed by using embedded optical fiber composite FRP intelligent bolt.A set of on-line real-time monitoring system for weathering rockfall of high rock slope is established.The main conclusions are as follows:(1)Joint and fissure planes of the upper and middle slopes of Xincai Tunnel slope are well developed,especially the upper weathered rock mass.The rock mass is cut by joint and fissure,and the slope surface is relatively fragmented.There are some loose rock blocks on the slope surface,and three dangerous rock zones are found.(2)Through quantitative calculation and stereographic projection analysis of the stability of dangerous rock slope,it is found that there exists a space condition of slip along the fracture combination surface when the slope is partially cut by joints and cracks.Therefore,it is more likely to predict the local failure of the slope under adverse factors(such as rainstorm),which is manifested by the collapse or roll of rock blocks on the local slope surface.Zhixincai Tunnel Road Safety.(3)Through the determination and study of the formation mode of dangerous rock fall,the movement path of dangerous rock fall is calculated theoretically,and the simulation calculation of the movement path of dangerous rock fall is carried out by using Rocfall,a computer numerical simulation software.It is found that the SNS passive protective net(5 m high)can no longer block all rockfalls,and further control measures are needed.(4)According to the principle of fiber Bragg grating strain sensing and the fabrication technology of FRP bolt,an embedded fiber composite FRP intelligent bolt is made.It has the superiority that the traditional monitoring methods of steel bolts can not match,and provides a reliable basis for the online real-time monitoring system of slope.(5)Combining with the engineering geological characteristics of Xincai Tunnel,the active-passive treatment method of dangerous rock is proposed.The main active protection modes are shotcrete on slope and active protection net hanging outside;the passive protection modes are planting protective forest,passive SNS flexible protection net and new steel structure shed tunnel opening.According to the traffic flow and its importance of the new color tunnel,an on-line real-time monitoring system based on embedded fiber-optic composite FRP bolt is proposed to monitor the generation and spalling of weathered rocks on high rock slopes,which has the effect of real-time monitoring and on-line early warning.