The Research On Safty Risk Assessment And Disater Control Technology Of Metro Shield Construction In Xi’an

Reseach of risk assessment theory and disaster control technology has importanttheoretical significance and engineering value for metro shield construction in Xi’an. Thispaper took Xi’an subway line2as background and studied with the methods of theoreticalanalysis,numerical simulation and field practice. The main conclusions follow:The main influencing factors of risk during subway tunnel shield construction in Xi’anwas proposed, which includes engineering geological and hydrogeological factors, loadfactors, construction factors, external factors and other four primary factors. And each primaryfactors contains several secondary influence factors. It established the identification method,identification basis and identification process construction of Xi’an metro shield risk, and usedAHP analysis the relation between the four primary factors and secondary influence factors.The four grade definition of Xi’an metro construction risk was given, fuzzy comprehensiveanalysis method which can quantitative evaluat risk grade of Xi’an metro shield tunnelconstruction was put forward by using fuzzy mathematics and analytic hierarchy processtheory, and the safety risk assessment method of Xi’an metro construction was established.Based on the characteristics of Xi’an metro shield construction with complex surfaceconditions, through multiple cultural relics and built (structure) constructed which was incollapsible loess area, Xi’an metro construction disaster prevention and control technologywhich can forecast and control the shield construction disaster was proposed. The main stepsas follows: first using numerical simulation to predict of surface deformation law induced byshield construction, secondly making reasonable construction scheme to control surfacedeformation according to the surface deformation law, finally using field monitoring andinformation construction technology to adjust construction schem in time, ensure theconstruction safety. The grade division of construction risk induced by tunnels shield construction acrossingrailway, bridge and the ancient city wall from Anyuanmen to North Street of Xi’an metro linetwo was completed. The use of disaster prevention and control technology reduced disastergrad of shield construction through the Longhai railway, the North Gate City wall and moatbridge. The deformation law of Longhai Railway subgrade, moat bridge and North Gate Citywall was studied by FLAC3D. Field practice shows that, disaster prevention and controltechnology is reasonable and effective.Risk assessment method and disaster control technology of metro shield construction inXi’an has important theoretical significance and engineering value. It can provide thetechnical support to prevent disaster for Xi’an metro construction. Deformation controlmeasures of shield tunnel through Longhai railway, the moat bridge, the ancient city wall canprovide references for the similar engineering.