Influence Of Large Section Shallow Buried Tunnel Construction On Vertical Deformation Of Soil Layers In Hangzhou

In this paper, the author analyzes the vertical deformation on Hangzhou large section shallow tunnel on the basis of previous theoretical analysis, numerical simulation, field measurement, the main contents and conclusions are as follows:1 Using the finite element software ABAQUS to analysis the effects of different excavation steps on ground deformation during CRD construction method, In the CRD method, Surface settlement is far more than the maximum 30 mm after the excavation of the first part, so the tunnel should be timely supported to control the deformation; meanwhile, the author analyzed the vertical deformation of CRD method、CD method、step method, The maximum surface subsidence relationship is: step method> CD method > CRD method. At last, the author analyzed the method of CRD method of three conditions and gets some practical conclusions.2 Analyzing the twin-track tunnel excavation under different pitch axis、different depths, the laws of deformation are given; Using the horizontal distance coefficient C value to judge whether the surface deformation curve shape is unimodal or bimodal; Secondly, Giving the piecewise function to analyze the surface settlement width. Meanwhile, maximum surface settlement is corrected in this paper, and then the author give the formula about the surface settlement. At last, It is found that finite value is close to the prediction formula value after compared with each other.3 Analyzing the subsurface settlement under different depths, the laws of deformation are given; Combining with the Mair formula, the author correcte the subsurface settlement width, maximum subsurface settlement,and then give the formula about the subsurface settlement. It is found that finite value is close to the prediction formula value after compared with each other.4 The low of the longitudinal deformation and the formula in the different z/D(depth / diameter) are obtained by analyzing the longitudinal deformation of twin-track large shallow buried tunnel.5 Using the monitor data to analysis the surface settlement and subsurface settlement, making comparisons between the monitor data and finite value and calculated value. forecast formula is similar to the monitoring data in the general trends and patterns, the numerical difference is less than 20%; Vertical forecasting formula can be applied in tunnel deformation prediction.