Study on feature of dangerous rock of Purple Mountain in Tibet and its stability and movement characteristics
XU Tenghui;JIN Wenxiang;SUN Shuqin;QIAO Yuan;State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology;
Dangerous rock is one of the common types of geological disasters in mountainous regions,of which the movement characteristics of the instability-collapse is quite difficult to be predicted,while its hazard is great. In order to explore the stability and movement characteristics of dangerous rock,the stabilities of all the dangerous rock zones are qualitatively and quantitatively evaluated herein by taking the dangerous rock of Purple Mountain in Tibet as the study case,and then the impact from freeze-thaw effect on the dangerous rock is analyzed through the relevant lab experiment with the movement trajectory after the instability of it simulated by the software of Rockfall,while the in situ verifications are made on the division of the dangerous rock zones,the strata lithologies and the joint-fissure developments in combination with the means of UAV images,3 D laser scanning and field investigation. The result shows that all the dangerous rock zones are located at the steep cliffs of the mountain ridges under the conditions of basic stability and unstability,of which the stabilities are to be lowered to some extent under the conditionsof rainfall and earthquake. Through the study,it is obtained that the formations of the dangerous rocks are impacted by many factors,i. e. topography,lithology,earthquake,freezing-thawing,etc.,in which the freeze-thaw effect is mainly exhibited as the freeze-thaw damage along with micro-cracks formed on the rock surface. After the instability-collapse,it is to bounce and roll on slope surface and finally stop. The study result can provide a reference for the design of dangerous rock prevention.