The Establishment And Application Of Mountain Tunnel Project Construction Environmental Risk Index System

Many big tunnels in China, such as Liangshan tunnel, Dabashan tunnel, and Da yaoshan tunnel, have great influence on the environment during their construction, bringing various environmental damage like drying up the surface water and the ground’s collapse. Meanwhile, as the period of tunnel construction lasts, large drainage will also raise problems. However, compared with the risk of construction security, the environmental danger of tunnel construction has been paid less attention, the most important one of which is the environmental risk of ecological environment. The seventeenth major report of the party points out clearly that to destroy ecological environment does not accord with the policy of "ecological civilization" Thus, the analysis of environmental risks and the countermeasures during the tunnel construction of mountain areas is of huge significance.The paper first discusses the theory and method of the risk evaluation, including risk connotation, risk identification, risk estimation and risk assessment, based on which we establish the environmental risk index system of mountain tunnel construction according to the establishing principles of Risk Index System.With the sixth tender of Lan-Yu railway, Zizhuyuan tunnel, as the object, we conduct the environmental risk evaluation of the construction through the AHP Fuzzy Comprehensive Evaluation and draw a conclusion that the risk assessment turns out to be "high risk". The result shows that during construction the indicators of high risk cover the physical and chemical influence risk C1(weight0.188), dust risk outside the tunnel C4(weight0.07-91), dust risk inside the tunnel C6(weight0.0764), risk of soil erosion C18(weight0.2006) and risk of surface water depletion C18(weight0.107). According to the study, the environmental damage and risk mainly result from the waste water, discard ballast, gushing water and blasting and so on. Aiming at the above problems, we have proposed the corresponding control measures in this research.