| In mountainous regions of Yunnan Province,the development of dangerous rock masses on steep slopes on both sides of hydropower stations has become a key area of research for engineering prevention and control due to the potential risk of rockfall hazards.This paper takes the hazardous rock masses on the slope of the Xiaowan hydropower station as the research object,investigates the background,genesis mechanism,and failure mode of these rock masses,analyzes their stability,and studies the influencing factors of rockfall movement characteristics.The main research results of this paper are as follows:1.Using unmanned aerial vehicle tilt photogrammetry and airborne Li DAR remote sensing survey technology,a three-dimensional disaster scene model of the study area was constructed,and 172 hazardous rocks,70 isolated rocks,and 33 groups of hazardous rock mass and isolated rock mass were identified on both sides of the hydropower station.2.Based on the investigation results,the background and genesis mechanisms of the hazardous rock masses in the study area were analyzed.The results show that the geological features of the region,river systems,climatic vegetation,and human interference are the main factors influencing the formation of hazardous rock masses.According to different failure mechanisms,the hazardous rock masses were classified into four types: landslides,toppling blocks,falling rocks,and isolated rocks and rock groupings.3.The structural characteristics of the hazardous rock masses were obtained by three-dimensional measurements of the disaster scenes and field inspections.The stability of 236 single hazardous rock masses was analyzed using the Chi-Ping projection analysis method.The results show that five hazardous rock masses are in an unstable state,114 hazardous rock masses have poor stability,88 hazardous rock masses are basically stable,and 29 hazardous rock masses are in a stable state.The stability of hazardous rock masses under different load combinations was calculated using fracture mechanics.The results show that the hazardous rock masses are stable under natural conditions,unstable under rainfall conditions and especially unstable under heavy rainfall conditions.The tensile stress generated by the crack water pressure is the main reason for the dangerous rock masses failure close to the structural surface under heavy rainfall conditions.4.The Rockfall software was used to study the influence of different parameters such as rock mass quality,launching height,slope features,and slope angle on the movement characteristics of falling rocks.The results show that the kinetic energy parameters of falling rocks mainly depend on the size of the rock mass when a high-altitude hazardous rock fails.When the hazardous rock fails of middle-and low-altitude positions,the steepness of the terrain slope and the higher proportion of exposed bedrock surface area lead to higher bounce heights,faster speeds,and greater impact kinetic energy of the falling rocks.5.Using Rockfall software to simulate rockfall movements at six characteristic profiles in the study area,it was found that the hazardous rock masses on profiles 1-4 have a minor impact on important buildings downhill after failure.Furthermore,their protective measures are adequate and do not require additional protection measures.However,hazardous rock masses on slopes at profiles 5 and 6 could threaten the main buildings of the hydropower station after instability,so existing protective capacity should be improved,and additional protective measures should be established accordingly. |
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