The Comparing Study On The On-sit Monitoring To Physical Mode Test And Numerical Simulation Of Closely-spaced Tunnel

As a particular kind of tunnel, Closely-spaced tunnel's distance of two lines is bigger than that of neighborhood tunnel, but smaller than that of two single parallel tunnels. Because of many advantages, such as high flexibility to different landform, smooth line shape, less occupation of space, relatively short construction time and low cost, closely-spaced tunnel is gradually attached more and more importance in recent years, but the information about the design and construction of closely-spaced tunnel is very lack in our country currently. Especially, the shortage of research to soft rock closely-spaced tunnel with different altitude and unsymmetrical press is very insufficient.In this dissertation, some methods, such as on-site monitoring, physical mode test and numerical simulation, are used to study the tunnel named Ping-Nian in Yunnan province. The physical and mechanical effect of closely-spaced tunnel with different altitude and unsymmetrical press are systemically analyzed, especially that two lines' distance is bigger than 10 meters. Simultaneously, the reasonable constructing order, constructing mechanical behavior, interaction to each other and the stability of the rock column between two lines are emphasized on. All the obtained conclusions are as follows.--Currently, the research to closely-spaced tunnel is emphasized on soft rock area, moreover, the main research contents are study on optimizing the two line's distance, construction technique, stability of surrounding rock and rock column between in two lines, security of the old tunnel and so on.--Through on-site monitoring for Ping-Nian closely-spaced tunnel, it is found that the deformation of surrounding rock is mainly elastic; moreover, there is dimensional effect for the deformation of surrounding rock. Further more, there is linear relationship for the distance of testing point from the place of internal displacement to the edge of tunnel.--Through dynamic feedback-forecast for Ping-Nian closely-spaced tunnel, it is found that the disciplinarian of cave for dynamic feedback-forecast result and on-sit monitoring is basically same; moreover, the relative error is smaller than 15 percent. This illustrates that TSSP program is also applicable to closely-spaced tunnel with altitude difference, unsymmetrical press.--To the left tunnel: when excavating right tunnel first, the settlements of ground surface and deep level are bigger than that of excavating left tunnel first; whether excavating left tunnel first nor right first, the influence of tunnel excavating later to left tunnel is bigger than that of first tunnel to left tunnel.--The influence of tunnel excavating first to tunnel excavating later: when excavating right tunnel first, the influence of ground surface and deep level settlements of tunnel excavating latter to tunnel excavating first are bigger than that of excavating left tunnel first.--Influence to the middle rock column: when excavating right tunnel first, the final ground surface and deep level settlements of the middle rock column are bigger than that of excavating left tunnel first; whether excavating left tunnel first nor right first, the upper part of the middle rock column mainly bears horizontal stress; relatively the under part of the middle rock column mainly bears vertical stress.--To closely-spaced tunnel with altitude difference and unsymmetrical press, which is low covered, it is advantageous to excavate left tunnel.