Time-space Effect Of Rock And Support Interaction In Subway Tunnel

As its characteristic of high cost and complexity, tunnel project has been paid closeattention all the time. Tunnel project study is divided into two categories by the way ofresearch object in this paper: one is inside the tunnel, this kind of study in the tunnel isabout the change of mechanics and displacement of surrounding rock and the resultingof support force during the excavation of the tunnel; the other is the affection onunderground structures closed to the tunnel and pipelines or building(structure) in theupper strata or surface caused by the excavation of tunnel. These two types of problemsbecome complexity because of the different physical properties of rock and soil and thetime-space effect of excavation cycle. For a long time scholars made great achievementon the problem of time-space effect in tunnel, but accident still take place sometimes inthe actual tunnel engineering both inside the tunnel or in the surface. So time-spaceeffect of rock and support interaction in subway tunnel need further study. This paperstudies the time-space effect of rock and support interaction in subway with the methodsof theoretical analysis, site monitoring and numerical simulation, the main work is asfollows:1) this paper tries to analyze some theory about tunnel excavation, expound thebasic principles of constraint convergence method. In three-dimensional space, due tothe presence of tunnel face in target section, surrounding rock is affected by a virtualforce provided by the tunnel face, its stress and displacement is not fully released evenignore the creep effect. With the advance of excavation face, the virtual force providedby tunnel face disappear gradually, the surrounding rock stress-strain continue to release,along with the supporting erection and begin to play a role in this process, however,makes the surrounding rock and supporting to achieve a new state of equilibrium. In thispaper, the virtual force caused by working face is supposed as a contact link, andmaking a matlab program to plot characteristic curve and safety factor curve of liningvia the relationship between the virtual force and stress-train of surrounding rock andlining, and then by changing the value of key parameters (excavation footage,excavation cycle time, the radius of tunnel and rock mechanical properties) to discussthe time-space effect during tunnel excavation.2) the object of study in theoretical analysis way usually is a circular tunnel and thethree-dimensional problem is reduced to the plan. For the three-dimensional space shaped like a horseshoe-shaped tunnel, it is more difficult to get an accurate analyticalsolution by the theoretical calculation method. Another aspect of study in this paper isrelying on the project of Chongqing Metro Line6Phase2Jinshan Temple to southbridgehead of Jialing River tunnel excavation to monitor the interaction force betweenrock and lining, deformation of rock and lining and settlement of building in surface. Atthe same time making use of finite element software ABAQUS to simulate the actualtunnel excavation process thus to study the development status of stress anddeformation of surrounding rock, lining force and building settlement in supper surfacewith ABAQUS’s powerful nonlinear analysis capability, and then compare the actualtunnel project monitoring data with the theoretical analysis and numerical simulationresult to find out the law of surrounding rock stress and deformation, characteristics ofthe supporting force and surface buildings settlement during the time of the tunnelexcavation.