Research On Seismic Risk Of Mountain Tunnels Based On Fuzzy Comprehensive Evaluation Method

With geological movement activing and the earthquake occurring frequently in recent years,some strong earthquakes have caused severe damage to some underground structure.The research on the seismic response of tunnel and underground engineering has just started in china.At present,there is no unified classification and evaluation method for the earthquake damage of tunnel,and mountain tunnel hasn’t been brought into the risk management category,let alone set up fast and efficient tunnel earthquake risk assessment system.Based on the damage materials and basis data of mountain tunnels collected in Wenchuan earthquake,this thesis has a deep research on the earthquake damage form and regular pattern of mountains tunnel,analysis the reckoning mechanism from multi-aspects,and set up the earthquake damage database preliminarily.Fuzzy comprehensive evaluation system on earthquake damage of mountain tunnel is developed based on risk management theory by using the fuzzy comprehensive evaluation method,AHP,theory analysis,model testing and value simulation.Seismic risk assessment is carried on to 25 tunnels in Yaan-Shimian-Lugu Expressway under construction,and risk deal measures are put forward verified by many ways.The major work done in this paper is listed as followings:1.A large number of detailed fundamental materials of tunnels including earthquake investigation,special inspection data and tunnel design,construction and operation maintenance information are collected;the Wenchuan earthquake damage database with 59 mountain tunnels is established.2.Earthquake damage form and regular pattern of mountain tunnel is summarized;the tunnel earthquake damage mechanism is explored in detail in the application of numerical simulation technology,large shaking table model test and theoretical analysis method.(1)Differential Stiffness between tunnel lining and surrounding rock is an important factor to the severity of tunnels,and should be matched on the basis of meeting static condition for tunnels by adopting the shock absorption measures.(2)Seismic response characteristics of tunnels are put forward,and the severity is evaluated according to portal sections,common body,fault zone and fractured zones.(3)Severity of seismic damage attenuates quickly with the epicenter distance,relatively serious and serious seismic damage of tunnel mainly focuses on the distance from the seismogenic faults within 10km,the moderate is within 10 to 20km.and there is no relatively serious and serious seismic damage outside 20km.(4)Severity of seismic damage of tunnels across fault and fracture zones is related to fault movement;it is most serious in narrow fault movent,the second in wide fault movent,and is the light in the fault without rupture.(5)In high intensity earthquake areas,the earthquake damage is serious when the intersection angle between tunnel axis and seismogenic faults is 60-90°,and is relatively light when it is 30-60°.3.Quantitative index is put forward to evaluate severity of seismic damage of tunnels affected in Wenchuan earthquake according to portal sections,common body,so do the main influencing factors on seismic damage to establish membership function distribution and determine the earthquake risk factors on tunnels.4.Fuzzy comprehensive evaluation system on earthquake damage of mountain tunnels is developed in the application of fuzzy comprehensive evaluation method,AHP and theoretical analysis method.Furthermore,sensitivity analysis is carried out on the influencing factors,numerical simulation technology and large shaking table model test are adopted to verify reliability of the system.A visualization software system is developed.5.Seismic responses of mountain tunnels in Wenchuan earthquake zone are validated by using tunnel fuzzy comprehensive evaluation system for earthquake damage.6.Seismic risk assessment for 25 tunnels in Yaan-Shimian-Lugu Expressway under construction is carried out,and risk deal measures are put forward and verified by shaking table model test and numerical simulation method.