The Research Of The Luwan Tunnel Construction Phase Risk Assessment And The Numerical Simulation

Since the economic and culture of the society are developing rapidly after the17th CPCNational Congress, both road and rail traffic has been unable to meet their basic requirements.In order to promote local economic development, it is one of the government’s major tasks toaccelerate the development of transportation construction of the remote area especially themountain area. However, a variety of known or unknown risks exist during the constructionof tunnel because of the technical requirement, the complicated process, the imperfectmanagement and the uncertain factors. These risks threaten the life of the constructionpersonnel and the machine, some of them may even paralyze the whole project. So it is ofgreat importance to make a risk assessment of the tunnel construction project for the safety ofthe personnel and machine and control of the cost as well as ensuring the time limit andquality for the project.Taking the Luwan tunnel as the research background and in combination with expertconsulting method、fault tree analysis and numerical analysis, the tunnel construction safetyrisk management and the hole construction was analyzed. The research and the mainconclusions are as follows:The thesis made a brief introduction about the latest development of the risk assessmentat home and abroad. The connotation of the highway tunnel construction safety risk, theprocess, method and index of risk assessment were included. The highway tunnel constructionsafety and risk management system is established.Using questionnaires and expert consultation method, identify the Luwan tunnelconstruction safety of the main risk factors, it is concluded that the bay road tunnelconstruction are large deformation, hole instability risk, object against risk, such as trafficaccident risk eleven security risks. The evaluation model is established by fault tree analysisand the probability of each basic risk factor is obtained by expert consultation method. Theprobability of occurrence of each risk events is calculated by fault tree analysis and is sortedby importance. Discovery bay road tunnel in the process of construction, the geological riskcaused by large deformation and the hole instability of the probability of occurrence of a riskis the biggest, the qualitative analysis is made on each risk event and countermeasures aregiven.In view of the large deformation, the hole instability risk,an analysis on the large-spanbias shallow buried tunnel hole technology was made by using FLAC3D software. Importantparameters of the wall rock during the hole tunneling process such as the vertical stress anddisplacement、internal force of the primary support while using double side drift method. Itwas found that the excavation of right heading and upper bench influence the wall rock mostobviously, the change amount of the vertical displacement and the horizontal displacement and the surface subsidence were comparatively larger. Large deformation increased risk;Theexcavation of the upper bench influence vault subsidence obviously and will probably lead toa hole instability risk. Therefore, it is necessary to strengthen the monitoring measurementand improve the construction quality of each aspect. Besides, a phenomenon of stressconcentration tend to occur during the excavation of left heading and lower bench. Therefore,it is rational to strengthen the construction quality of lock foot bolt.In this paper, the research results of large-span bias stage of shallow buried tunnelconstruction safety risk management and the hole construction technology research hasreference and application value.