Construction Risk Assessment And Control Measures For TBM Crossing Fault Fracture Zone

When the TBM method encounters bad geology such as fault fracture zone in the construction of deep and long tunnels,due to the poor adaptability of TBM to the sudden change of geological environment,it is very easy to lead to construction safety accidents such as jam,resulting in serious economic losses and delay of the construction period.It is an effective way to ensure the efficiency and safety of TBM tunneling by clarifying the pregnant risk environment,disaster-causing factors,and their correlation,optimizing TBM tunneling parameters,and formulating a targeted support scheme for TBM tunneling.By using the methods of literature investigation,data mining,and theoretical analysis,this thesis probes into the risk factors in the construction process of TBM crossing fault fracture zone,extracts the main weight indexes,establishes a risk assessment model which can describe the construction process of TBM,uses HAZOP analysis method to analyze the construction safety risk of TBM construction technology,and puts forward the risk management method of TBM crossing fault fracture zone construction process.Finally,combined with the Gaoligong Mountain tunnel project case to verify the above methods,the main research contents and results are as follows:(1)Through the literature research through Cite Space,taking the current research trend of TBM-risk assessment and management as the object,based on bibliometrics and knowledge graph,build the mode layer and data layer of TBM construction process,and construct the ontology knowledge graph of TBM construction safety progress model.This thesis summarizes the sources of seven main risk factors encountered in the construction of TBM crossing the fracture zone: design scheme risk,geological risk,hydrological risk,mechanical failure,technical risk,construction management risk,and material risk,etc.,and forms the evaluation index system of construction risk of TBM crossing fault fracture zone.(2)According to the risk knowledge graph and evaluation index system of TBM,using the evaluation method combined with the AHP-Fuzzy method,through the hierarchical model construction,weight calculator,time and consistency analysis of the process of TBM crossing fault,the hierarchical index synthesis set and index evaluation set of TBM crossing fault fracture is formed,and the membership function and its membership degree are determined.(3)Combined with the construction technology of the TBM crossing fault fracture zone,the relationship between HAZOP risk information and control measures in the TBM construction process is studied,and the accident emergency disposal information module and the database in TBM crossing fault construction process are established.Based on the five stages of preparation,initiation,advance,stop and tool change,arrival and reception of TBM,the nodes are divided for HAZOP analysis.According to the types and characteristics of possible TBM construction accidents,the causes of accidents,the evolution path of follow-up risks and emergency countermeasures are studied.(4)Through the establishment of a knowledge graph and the analysis of AHPFuzzy risk assessment and control countermeasures,it is concluded that the safety grade of TBM driving in the fault fracture zone of Gaoligong Mountain tunnel is III.By comparing and analyzing the on-site accident disposal situation and the accident comprehensive response method in the construction process of the TBM crossing fault fracture zone,it is proved that the method in this thesis is consistent with the on-site disposal strategy.The research results can provide theoretical and technical support for safe tunneling and accident prevention of TBM passing through the broken zone.