Risk Evaluation Of Dangerous Rock Mass At Dam Abutment Of Dahuaqiao Reservoir Based On ROCPRO3D

Since the completion of Dahuaqiao Hydropower Station,the dangerous rock mass on both sides of the steep cliff has collapsed and fallen many times,which not only damages the equipment,but also poses a great threat to the safety of personnel and vehicles in the reservoir area.Therefore,evaluating the stability of the dangerous rock mass on both sides of the reservoir and the risk of the whole reservoir area from the collapse disaster can provide a great guarantee for the safe operation of the reservoir area.Nowadays,the risk assessment methods of geological disasters are mostly based on probabilistic methods,which realize the risk and risk assessment through statistics of factors affecting the stability of rock mass and assigning values.With the widespread use of UAV and the rapid development of rock fall trajectory simulation software,more possibilities are provided for the stability of dangerous rock mass in a small area and the evaluation of the risk of collapse of specific disaster bearing body.In this paper,the UAV technology is used to identify the potential dangerous rock mass in the reservoir area,and then ROCPRO3 D software is used to simulate the rockmass collapse movement trajectory in the unstable or unstable state.Then the dynamic parameters in the grid generated by the software are selected as the evaluation factors for risk assessment.Finally,the vulnerability assessment in the reservoir area is calculated and the risk assessment results are obtained.Specific work contents and achievements are as follows:1.Understand the basic situation of dangerous rock mass in the study area and establish a high-precision three-dimensional image model of the study area through field investigation and UAV flight operations.Based on the model,282 pieces of dangerous rock mass were identified manually,and the information of each dangerous rock mass and the control plane of each dangerous rock mass were measured and counted.The stability of dangerous rock mass was qualitatively analyzed by drawing the polar radiation erakeria projection map with the statistical structural plane information.Finally,the stability of each dangerous rock mass under three working conditions was quantitatively evaluated by using static analysis method.The quantitative evaluation results showed that many dangerous rock mass had poor stability under the working conditions of rainstorm and earthquake.2.ROCPRO3 D software is used to simulate the movement trajectory of each dangerous rock mass after collapse for 61 dangerous rock masses whose stability is in an unstable or unstable state.In order to reflect the randomness of rockfall movement,each dangerous rock mass is set in the software to simulate 50 times of collapse respectively with a probabilistic model.The kinetic parameters such as speed,bounce height and energy in the movement path of each dangerous rock mass were obtained,and the harm range,threat object and region of the dangerous rock mass on both banks of the study area were studied and analyzed.The simulation results show that when the dangerous rock mass with poor stability collapses under the conditions of rainfall and earthquake,the water inlet,the road on the left and right banks and the tunnel entrance tunnel are all within the influence range of collapse.In addition,the speed,bounce height and rockfall track frequency values in the 5×5m grid in the study area were calculated statistically,and these data were used as risk assessment factors to establish a risk assessment system to evaluate the risk of the study area.Finally,the distribution map of the collapse risk of the study area was obtained.The results showed that the risk of the switch station and the highway on the right bank were at a high level.On the left bank,the highway and the entrance of the traffic tunnel are at a moderate risk level.3.Disaster-bearing bodies are divided into fixed disaster-bearing bodies of engineering buildings and mobile disaster-bearing bodies of personnel and vehicles,and the impact force of each dangerous rock body with poor stability when it impacts engineering buildings is calculated according to the formula.Meanwhile,the impact bearing capacity limit of plate members such as shed and switch station is calculated according to the specifications.As the calculation of road vulnerability is difficult,0.1 historical disaster experience value is selected to calculate it.Based on the daily vehicle flow and pedestrian flow data of each section in the study area,the annual accident death rate of each section was calculated to obtain the vulnerability of the mobile disaster bearing body in the study area.Finally,the maximum vulnerability of fixed disaster bearing body and flowing disaster bearing body is assigned to each grid,thus obtaining the vulnerability distribution map of the study area.Risk evaluation can be calculated by multiplying risk and vulnerability,and then the distribution map of risk evaluation can be drawn.The risk evaluation distribution diagram shows that the collapse risk of the switch station section and the highway section of the upper dam on the right bank is in extremely high ~ high risk,while the risk of the highway section on the left bank,the highway section on the upper dam on the right bank and the highway section of the reservoir on the right bank is basically in low ~ very low risk.