| Forecasting and controlling the ground settlement induced by excavation is very important in constructing city subway tunnel with shield driven method.Combining with shield tunneling practice of Chendou No.1 Lot.3 subway,on the basis of field measuring and testing,theoretical analysis and numerical simulation,this thesis makes a study on the behavior of ground settlement induced by tunnelling in the special stratum of gravel layer.The main research results are as followings:1.The mechanism of ground settlement is discussed based on analysis of the geometrical effects and mechanical effects of EPB shield construction.2.On the basis of monitoring data,and considering tunnel depth,geological condition,opening parameters and other influential factors,the characteristics of soil deformation induced by EPB shield tunnelling in the interval tunnels from gymnasium of province to square of Tianfu railway station in Chengdou No.l Lot.3 Subway are analyzed in this thesis.Then the development process and distribution of the ground settlement are obtained.3.Using the monitoring data,it studies into the main influential factors on the ground settlement,such as earth pressure in the cutter chamber,routing parameter and slag tapping control.It also discusses several large settlement caused by setting inapprapriate construction parameters and achieved many useful conclusions.4.Using the monitoring data, the characteristics of soil deformation induced by EPB shield tunneling are analyzed in this thesis. Then the effect of structure and foundation near by tunneling on the shield excavation process are obtained.5.Using 3D Fast lagrangian Analysis of Continua,FLAC3D with Mohr——Coulomb yield ctiterion,a 3-D numerical simulation of structure and foundation near by tunnel from Xiaotianzhu to square of Tianfu railway station are carried out,during which the factors of ground loss,earth pressure in the cutter chamber and grouting pressure have been considered.
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