Risk Discriminate And Control Of The Collapse Disaster In Mountain Tunnels

Mountain tunnels engineering generally have a bad construction environment and many hidden hazards.During the construction process,it is very easy to encounter risk disasters such as water inrush,collapse disaster,which increases the difficulty of construction.In view of this situation,it is very necessary to choose risk identification and control measures before tunnel excavation.With Taoshan Mountain Tunnel No.2 as the background,,this paper firstly uses the fuzzy analytic hierarchy process to conduct a risk assessment of the fault-bearing section geology.Then,using the assessment results as a guide,use TGP206 to predict the surrounding rock disasters and set the corresponding risk control plan.Finally,combined with the actual excavation conditions,the feasibility of the risk assessment and control measures is verified to discuss the risk assessment for tunnel opening The important value of digging.According to this complete process,the main research results of this article are:(1)In view of the unfavorable geological characteristics of Taoshan No.2 Tunnel,three risk factors of collapse disaster,water inrush and anmud disaster selected as the three first-level indicators for risk assessment,and the corresponding 14 second-level indicators are used.The fuzzy analytic hierarchy process establishes a mountain tunnels construction risk assessment model.(2)Combined with the geological conditions,the fault-bearing section is geologically divided into 9 tunnel mileages,and the established construction risk assessment model is used to determine the risk levels of the 9 tunnel mileages.The results are as follows:Compared with 12%,medium-risk mileage accounts for 55%and high-risk mileage accounts for 33%.(3)Using the results of the risk assessment as a guide,use TGP206 to analyze the surrounding rock in front of the palm face of each risk mileage segment,detect the mileage of the specific disaster in the high-risk segment identified earlier,and predict the type of disaster to be collapse disaster.(4)According to the disaster situation forecasted by TGP206 in the early stage,the risk control plan is determined as the advanced grouting small pipes,and the risk control plan and the actual engineering geology related parameters are used as conditions to establish the finite element software Midas/GTS NX to construct the tunnel excavation The model analyzes the supporting effect of the risk control scheme on tunnel excavation through numerical simulation.(5)Comparing the risk assessment with the actual working conditions,it was found that in the high-risk section judged by the risk assessment,a collapse accident occurred in the non-risk mileage section predicted by TGP206,which illustrates the limitations of the advanced geological forecasting instrument.Only use the risk assessment conclusion as a guide to obtain more reliable disaster prediction results.(6)The combination of disaster mileage and numerical simulation results is basically consistent with the site situation,indicating that the finite element software can verify the feasibility of risk control measures,thereby optimizing the evaluation method,and further illustrating the risk assessment work to analyze and avoid disasters before tunnel excavation...