Prediction Method Of Ground Settlements Induced By Subway Tunnelling In The Loess Region

Although the Metro tunnel construction can reduce effect to the traffic on the ground,are being used widely, it will disturb rock mass inevitably, and the ground surface settlement is likely to influence the buildings overground and the existing pipelines underground. When the settlement achieves a certain stage, it will affect the safety of buildings and the utilization of pipelines. To reduce the damages, which are induced by tunnel construction, to the buildings overground and the facilities underground, analyzing the regularity of ground surface settlement exactly and forecasting are necessary. Sequentially, optimal construction techniques could be chose and perfect measures could be established to insure the safety of buildings and pipelines in construction area.Based on the classical stochastic medium theory, the expressions of ground surface settlement and deformation caused by shield construction are established in this thesis. And according the Peck method, the correction method of main influence angle of the upper rock tunnel is gave, making the calculation results and the measurde results closer. Using standard transform principle, the expression of stochastic medium theory are gave in polar coordinates; to explain the polar expression formula, suiting for any complex hole shape and large sections of tunnel engineering, expanding the application range of this method.Prediction of the ground surface settlement and deformation are used by this method in this paper in shield tunnel, shallow-buried tunnel, arch tunnel and large cross-section tunnel in the back of Xi'an No.1 subway line project. Compareing with the measured results using this paper forecasting method, it can be seen that calculated results are in good agreement with the measured results with theoretical analysis. It can be used in engineering practice.