Monitoring Of Rock Displacement And Stability Analysis In Qijiaya Tunnel

With the rapid development of the national economy, China has increasedinvestment in the construction of public infrastructure, especially in roads, railwaysand other transportation infrastructure. In recent years, geological and environmentalconditions for building the tunnel project become more complicated, so the designand construction of railway tunnels become more difficult. Many scholars and expertsfrom home and abroad have done a lot of research in railway tunnel through lots ofmethods like theoretical analysis, model testing, field testing and numericalsimulation, and achieved some results. However, due to the immature judgmenttheory and method of existing rock stability, the judgment on general tunnel is mainlybased on the change of surrounding rock’s velocity of displacement, while it is mainlyjudged with the on-site supervision and measurement if the geological conditions andthe construction environment of the tunnel are complex. So the deformation andstability of railway tunnel’s excavation become an important issue.In this paper, the research background is based on the Qijiaya Tunnel, and themain research work and achievements are:(1) Summary the monitoring measurement means of the railway tunnelsurrounding rock’s deformation and evaluation method for surrounding rock’sstability and evaluation methods of the stability of surrounding rock, and analyze theinfluencing factors.(2) Combined Qijiaya Tunnel geological conditions, lithology, hydrogeologicalconditions, adverse geological phenomena with site construction methods andtechniques, drawn a conclusion that the failure mechanism of tunnel surrounding rockand the main factors that affecting the stability of the Qijiaya Tunnel surroundingrock.(3) Supervise on-site and measure the data (vault subsidence and convergencedisplacement of a typical cross-section of the tunnel), select the optimum function andmake a regression analysis of the measured displacement data, plot a displacement-time graph and calculate the deformation rate of the surrounding rock’s deformation, determine the stability of the tunnel surrounding rock, and predict the finaldeformation of the rock, and determine the best secondary lining time.(4) Select Ⅲ, Ⅳ grade typical section of the Qijiaya Tunnel’s surrounding rock,make a numerical analysis of the force of its lining structure, draw the axial force,shear and bending moment of the lining section, and evaluate the stability of thesecondary lining support according to the safety coefficient of the lining structure.(5) Evaluate the stability of Qijiaya Tunnel’s lining supporting structure based onthe theoretical calculations and numerical simulation method, and no longer simplydetermine it based on the displacement reference which shown by the standard.