Analysis Of Stress Characteristics Of Highway Bridge And Tunnel Above Mined-Out Regions And Prediction For The Ground Settlement

It is of challenge and emergent problems for hazardous assessment and treatment technology for the mined-out regions under the highway with bridges and tunnels, and research on deformation and stress characteristics of highway bridge and tunnel above mined-out regions has important theoretical and practical meaning. Based on the Fanshuigou bridge-Shipogou tunnel project which is above the mined-out regions in Liulin section of Qingdao-Yinchuan highway, hazardous assessment and treatment technology are discussed by combining numerical simulation and theoretical analysis methods, and the ground settlement deformation of mined-out region is also predicted by using an effective prediction method. The main research work can be summarized as follows:(1) Based on field research and investigation data, engineering geology analysis for the bridge and tunnel engineering sites is made as well as hazardous assessment for the mined-out regions.(2) After analyzing the existing modeling methods, a new method of coupling MIDAS/GTS and FLAC3D, where the data transformation implement- ed with the aid of MATLAB, is put forward against technical difficulties and limitations that appeared when modeling with FLAC3D for complex geologic body and engineering structures.(3) The 3D numerical model of Fanshuigou bridge-Shipogou tunnel engineering above the mined-out regions is obtained by using the MIDAS/GTS- FLAC3D coupling method, and then numerical analyses of the ground deforma- tion response,and tunnel lining and bridge structural deformation as well as their structural forces by using FLAC3D are performed. The processes are gene- rated in the step-by-step mining region for treatment after mining coal in Tongde area. And then, Shipogou tunnel is excavated and Fanshuigou bridge constructed. The surface deformations under different working conditions have been revealed; and the ground subsidence basin characteristics and the central subsidence position have been determined. Besides, the deformations and forces of key bearing parts of tunnel lining and bridge have also been predicted.(4) A Usher model used for ground settlement prediction is proposed on the basis of its feasibility analysis; and through comparisons on several existing calculation methods of the parameters in Usher model, Origin software is adopted for parameters solution, and after this, the predicted results are compared with the measured data and those obtained by the hyperbolic model and grey model, which indicates that the Usher model can be used in ground settlement prediction and give good results.