Construction Optimization And Safety Control Of Double Hole Tunnel With Large Cross Section Based On GangKengShan Tunnel Engineering

Based upon the GuangKengShan tunnel engineering,according to the engineering geological conditions,shallow buried bias and poor lithology section,through theoretical analysis and numerical simulation analysis,combined with the analysis of the construction site monitoring,measurement test and observation results analysis,the research is carried out about under complex conditions of large section tunnel construction,mainly about the research of construction optimization and safety control of the tunnel,the main conclusions are as follows:(1)Based on the tunnel construction,the thesis carried out the safety risk assessment,drawing the conclusion that the tunnel is high risk(level III).The results show that the collapse and large deformation of complex surrounding rock sections are main risks during the tunnel excavation and support process.Accordingly,the technical countermeasures for large deformation and collapse risk events are formulated,which provide a theoretical basis and technical guarantee for controlling the collapse and large deformation of the tunnel.(2)The numerical analysis model of the double side drift method and seven step three step method has been Established to carry out the research on the optimization method of construction,the results show that the double side drift method is better than the seven step three step method in the control of surrounding rock deformation,especially in the ground settlement.(3)According to the project,which under the condition of complex surrounding rock,the numerical analysis model of large section double hole tunnel excavation is established,to carry out the interaction study of double hole tunnel construction.The results pointed out that the space of the double tunnel face of GuangKengShan tunnel should be greater than 60 m(3.5~4.5D),in order to ensure the safety of tunnel construction while the tunnels are constructed.(4)That numerical analysis excavation of shallow buried tunnel bias,has been Carried out.The results show that the left arch and vault larger subsidence displacement and stressconcentration at the tunnel pipe roof support during the excavation process,the ground appears a larger settlement.In order to improve the overall strength of the surrounding rock and control the deformation of surrounding rock and surface,strengthening support and grouting are carried out in the process of construction.At the same time,it is pointed out that the lateral displacement of the central part of the pipe shed and the stress change of the pipe roof may be caused by the bias of the tunnel and the excavation of the right line.(5)Based upon the built model of GuangKengShan Tunnel Collapse Treatment numerical analysis,the thesis is carried out tunnel collapse treatment research of the project,and developed the corresponding technical solutions and technical measures.The site monitoring results show that the scheme and technical measures are reasonable and effective,which provides technical basis and reference for similar tunnels.