Multi-layer Repeat Disturbance To The Excavation Of Ground Surface Settlement Prediction And Control Technology

With the development of urban tunnels construction in China, people pay more and more attention to the influences to surrounding environment caused by tunnel construction. There are lots of damages about roads, pipelines and buildings results from the large ground deformation in engineering practices, and also so many domestic and foreign scholars have done extensive research. Based on previous research。With the funding of science and technology projects of Changsha City K0902027-1, this dissertation will analyze and summarize a variety of ground settlement prediction and control methods, which combine with Yingpan Road Xiangjiang River tunnel engineering practice and numerical simulations. Finally formulate a system method of surface settlement prediction and control under multi-excavation and disturbance. The main contents of this paper include as follows:(1)A11 sorts of settlement prediction formulas are summarized and the transverse settlement trough prediction methods for bifurcation, small spacing and space cross section of Yingpan Road Xiangjiang River tunnel are proposed. Then the forecasting methods of time-history curves about settlement for single surface point are also proposed.(2)Ground settlement theory and mechanism during tunnel excavation are analyzed and summarized. Through analyzing transverse settlement trough from single-peak to double-peak of the parallel round hole two-lane tunnel, the critical center distance formula is derived.(3)According to monitoring data of Yingpan Road Xiangjiang River tunnel, the dissertation analyzes the regularity of settlement of typical sections. The prediction model is evaluated by comparing the predicted results with the monitoring results and using relative error percentage. Then, the prediction equation is optimized by introducing fit parameters. The results show that settlements which are predicted by experience prediction formulas are larger than actual monitoring results. The relative error percentage of time-history curves about settlement for single surface point is about 7%. About 65% of settlement in this section is completed, when tunnel is excavated to across the section. The settlement begins to be stable after 60 to 80 days'subsidence.(4)The applying of large tube shed, anchor, and grouting are systematical summarized, also including strengthening mechanism, parameters selection and construction processes. The advance supports of Yingpan Road Xiangjiang River tunnel are analyzed.(5)FLAC3D software is used to simulate the construction process of Yingpan Road Xiangjiang River tunnel in which the main line cross ramp C and D. The influences of different construction methods and excavation to ground surface settlement are analyzed as well as deflection of advance support system.