Stability Analysis Of Overlapping Adjacent Tunnel Construction

In recent years,with the rapid development of urban construction,traffic facilities gradually perfect,the development of underground space is widely,it inevitably makes,the existing tunnel built around nearly meet the new phenomenon of tunnel engineering,and the scale is bigger and bigger,more and more close,the newly built tunnel with both to increase the probability of overlapped tunnel in,As a result,the security of the existing side and the stability of the new side are unavoidable and must be solved.Based on Zeng Jiayan renmin road bridge engineering of jialing river in chongqing branch tunnel,the subway line 10 interval tunnel,rail line 2 inward and outward channels formed by three overlapping tunnel near by tunnel construction as the backing,through numerical simulation and field measurement,the method of combining the three cavity vertical overlap almost meet the stability of the tunnel,better to guide the project construction work,research has certain theoretical significance and application value.The research approaches and methods,main research contents and research results are as follows:(1)According to the number of nearly meet tunnel and close way classification are studied,and by using MIDAS GTS software,the mechanical characteristics of different classification structure is analyzed,using the FLAC3 D,establish level and parallel circumstances more cavern tunnel near construction model,the distribution characteristics of surrounding rock stress field and displacement field of study,It is concluded that the construction sequence from bottom to top is more favorable to the structure stress for vertical and inclined close tunnels.(2)According to the characteristics of the project,using MIDAS GTS software for surrounding rock heterogeneity,and section size is not consistent and close after form has been in a change in three overlapping almost pick up in the tunnel construction the deformation of surrounding rock and supporting structure stress rule calculation analysis,finally it is concluded that the use of construction sequence,the steps from down to up excavation method,more beneficial to the stability of the surrounding rock and supporting structure.(3)Based on the element safety factor method of surrounding rock stability analysis,combined with the relevant knowledge of concrete structure design principle,the application of element safety factor method in tunnel structure stability analysis and calculation is studied.(4)Through the monitoring and measurement on the construction site,the correctness of theoretical derivation analysis and model calculation is verified.