| In shield tunneling construction, the strata disturbance and formation damage of shield tunneling will cause surface settlement.Therefore,it is meaningful to study surface settlement.Based on the background of Guanhui inter-city transit project,a research for surface settlement and support pressure of EPB shield has been done, using the method of combining theoretical analysis, numerical simulation and field measurement. The main research content is as follows:1. The relationship formula between settlement trough width factor i and tunnel buried depth Z has been confirmed using Gaussian peak function and relevant empirical formula in this paper.And the result turns out to be i=1.69Z0.73. This formula can be matched with the measured data preferably. The maximum surface settlement and the influence of settlement can be confirmed using i-Z and Peck formula. It has certain guiding significance for the construction and monitoring.2. In this paper, the correlation of surface settlement and time has been simulated, using Boltzmann function and the conclusion for prediction model of surface settlement. Boltzmann function can be matched with the measured data preferably.It may timely forecast potential surface settlement to avoid excessive settlement. Therefore, this model has certain practical value.3. Support pressure is an important parameter of EPB shield and an influence factor of surface settlement during the construction. In this paper, on the basis of summarizing the predecessors, the calculation of support pressure is modified.And the new calculation method matches well with this project, it has certain guiding significance for the management of support pressure.4. Plaxis3D Tunnel has been used to simulate the dynamic construction of EPB shield.This software considers the friction between soil and EPB machine, shield tail grouting etc. Simulation results intuitively show the ground movement laws,and match well with the measured data. |
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