Analysis On Surface Subsidence Law And Control Of Shallow Buried Tunnels In Cities

Urban subway construction can effectively solve the problem of traffic congestion, in the global subway construction has become the main way to open up underground space. However, the development and construction of subway tunnels are also faced with the construction of the surrounding rock and soil environment changes, adjacent to the building(structure) deformation and deformation of the surface settlement.(1)Under the condition of tunnel excavation, the surface subsidence law of different overturning shallow tunnel is numerically simulated. The deformation of the surface subsidence is gradually increased within 2.5 times of the span, and the depth is less than 2.5 times. The strong influence zone is 2.5D and the weak influence area is 2.5D.(2)Based on Midas / GTS, the selection and optimization of the different supporting methods of Qingdao subway shallow buried excavation are determined. By analyzing the economic effect and controlling effect, it is determined that the use of lengthened bolts, stratigraphic grouting and thickening of the two linings are the most economical and reasonable Support mode.(3)The ground subsidence law is consistent with the Peck empirical formula, and the maximum value of tunnel subsidence occurs at the center of the tunnel and gradually decreases toward both sides of the tunnel. The Peck formula is used to analyze the measured cross section data. It is determined that the surface subsidence groove width i is 8.47, the effective friction angle is 46.54° and the formation loss rate is about 1.15%. The results show that the prediction formula can predict the deformation accurately under the same stratum condition and depth, and the effect of the ground subsidence prediction under different depths of different sections is the best way to predict the deformation. So the Peck formula back analysis should be done under the same conditions.(4)The results show that the model has a small error in the prediction of the final result, and the logistic prediction curve of the ground subsidence is consistent with the Logistic model. Error is greater. Under the condition of early small sample data, Logistic model can predict the final settlement of surface subsidence over time.