Numerical Simulation For Construction Of The Small Spacing Tunnel On Adverse Geological Conditions

Due to complicated topographical and geological conditions as well as large numbers of mountainous areas, constructions of high-grade highway unavoidably meet with lots of tunnel works. As a result of special geological and topographical limitations, space of tunnels cannot satisfy with general technical codes. Therefore, such special structure shape as small spacing tunnel, twin-bore tunnel should be applied.This paper obtained from the tunnel adjacent formation pressure introduced the adjacent formation initial stress condition as well as the adjacent formation loose pressure definite method and introduced the adjacent formation destruction pattern and it's the influence factor; Through mechanics analysis which mutually affects to support structure the structure and the adjacent formation, has established the adjacent formation and support structure the structure state of equilibrium. Then, According tunneling characteristics of the force and based on the analysis of the basic theory about the interaction mechanism of surrounding rock and support structure, a computation model is made; a elasto-plastic finite element analysis model was applied to simulate the conventional procedure of tunnel excavation and lining with the finite element. By studying the effects of the parameter of lining, the mechanics of its performance are studied by researching the deformation of excavation, the force of lining and the distribution of axialforce.The paper takes design and implementation of construction measurement of jiuling tunnel as its basis. Based on the site measurement, ANSYS is adopted to simulate construction procedure for tunnel, stress field and displacement field for construction of close-spaced tunnels, and the research results are in a closing agreement with the site measured actual data.Regarding the simulation of the double-decked lining work, this article proposed three seed grafting gather the appearance interaction model, and two kinds of these have been carried on the numerical simulation, one kind is simulates the second lining with beam unit, one kind is simulates the second lining with plane unit. Through analyzed and carries on the contrast to draw some beneficial conclusions. In carries on to the tunnel excavates and supports and protects the process in the simulation, ANSYS simulates the material elimination and increases through kills and activation with the unit. Using the unit's function of life and death, may simulate tunnel's excavation effectively simply with the supports and protections process. But what must pay attention is when activates and kills the unit, degree-of-freedom should be controled.This paper mainly carried on the IV level surrounding rocks ,two kinds of models excavate the process the numerical analysis, and compared the initial period supports and protections biggest bending moment value, the initial period supports and protections biggest axle strength value, the anchor rod biggest axle strength value, the left hole to go against the nodal displacement value separately, the most greatly equivalent stress value along with to excavate the process the change rule. Simultaneously also carried on the V level surrounding rocks excavates the process the numerical simulation, tunnel's construction has provided some references for the bad geological condition.Finally this article discussed the each parameter's change of the IV level surrounding rocks under the different burying depth, has obtained the linear relationship conclusion between each research variable and the laying depth through the data and the diagram of curves change rule basically, influence qualitative analysis function for burying depth to tunnel construction process in each parameter.