| The unstable rock of Shangsilhai Protection Station in Jiuzhaigou County is located on the northwest high steep slope of Shangsizhai Protection Station.The unstable rock is induced by the “8.8” Jiuzhaigou earthquake.Due to the effect of seismic force,the structural fractures and unloading fissures of the unstable rock are relatively developed,and there are large tensile cracks at the trailing edge of the unstable rock belt.The overall stability of the unstable rock is poor,and the upper Sizhai protection station and the slope foot scenic road are on the lower part of the slope.Causes a serious threat.According to the geological environment conditions of the development of the unstable rock in the Upper Sizhai,the basic characteristics of the unstable rock development are studied through field investigation.Combined with the analysis of the red plane projection,the potential deformation and failure modes of the unstable rock are obtained.Using the empirical formula and RockFall software,the calculation is carried out.The motion characteristics of the collapsed rock are analyzed and the targeted treatment measures are proposed accordingly.The main research results are as follows:(1)Unstable rocks are distributed along the north-south direction.The bedrock is medium-thick-thick layered limestone.The unstable rock areas can be divided into unstable rock belt 1,unstable rock belt 2 and unstable rock belt 3,three from south to north.In the unstable rock belt,seven typical unstable rock masses are developed.Combined with the red plane projection analysis,the potential failure modes of the unstable rock mass are mainly falling,dumping and slipping.The formation and development of unstable rock mass are affected by many factors,such as topography,stratum lithology,geological structure,rock mass structure,slope structure,etc.In addition,earthquakes,rainfall,weathering and human activities also affect unstable rocks.Formation and development.The earthquake is a direct trigger for the collapse of unstable rocks.(2)Based on the limit equilibrium theory,the safety factors of typical unstable rock masses in the study area are calculated.The results show that the stability of each unstable rock mass is in a stable-basic stable state under natural conditions,while in heavy rain and VIII earthquake Under the intensity,it is unstable and basically stable,and it is mainly unstable.Therefore,the stability of unstable rock in the unstable rock area is poor,and it is more likely to collapse in the case of heavy rain and earthquake.(3)UDEC discrete element analysis software is used to simulate the typical unstable rock mass W1-2,and the unstable rock mass is in a stable state under natural conditions.In the heavy rain state,the displacement is slightly larger,and the vertical displacement is up to 18 cm,but The unstable rock mass did not collapse and was in an unstable state.Under the seismic conditions,the unstable rock mass collapsed in an integrated manner.The results obtained by the simulation are basically consistent with the results calculated by the formula method.(4)Using the empirical formula and RockFall software to calculate and analyze the kinematics of the typical unstable rock mass,the results show that the moving speed of the rockfall movement to the position of the slope is 25.47~28.95m/s,the rockfall energy 645.7~940.3KJ and bounce height of 2.5~3.6m indicate that the potential damage of unstable rock is large.(5)Based on the research on the characteristics and movement path of the collapse rockfall,combined with the protection object,the comprehensive treatment plan of the stone wall + passive protection network is proposed. |
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