Study On Deformation Characteristics And Construction Parameters Optimization Of Surrounding Rocks Of Shallow Large - Scale Tunnel

With the rapid development of China’s economy, more and more high grade road in the area is built with the increase of traffic volume, there are more and more shallow buried large section tunnel in highway construction. Because of the shallow and large section and small section tunnel in poor geological conditions, the surrounding rock stress state is complex, and therefore more difficult in aspects of design and construction. In this paper, the section of shallow buried tunnel as the engineering background, using research methods of theoretical analysis, field test and numerical analysis of combined deformation characteristics and construction parameter optimization research on surrounding rock of shallow tunnel with large section, draw the following conclusions.(1) In-depth analysis on the tunnel area geological background and engineering geology is done through collecting engineering geological data, site topography and geology, deformation factors summarized analysis of geological structure, rock deformation of tunnel surrounding rock and tunnel mechanism, determine the main factors of shallow buried large section the influence of tunnel surrounding rock deformation.(2)The deformation mechanism of rock mechanics characteristics of large section tunnel,surrounding rock excavation is analyzed, determine the boundary depth of shallow and large section tunnel. Using a variety of methods of shallow tunnel surrounding rock pressure of theoretical calculation and comparative analysis, draw the Xie JiaXiao theory is more applicable to the surrounding rock pressure of shallow tunnel with large cross-section calculation, and under the same condition, shallow buried tunnel and deep buried tunnel, the need for greater support strength.(3)Test data based on site monitoring, deformation characteristics of surrounding rock of shallow buried tunnel in the three-bench seven-step excavation method in the analysis, the deformation distribution of the relationship between time and space of shallow rock; relation curve of shallow buried section of tunnel ground settlement curve, the displacement around the tunnel with time and distance the distance of the tunnel face; the relation curve of the displacement around the tunnel and the fitting time fitting principle, the best fitting function,engineering reasons of large deformation of the tunnel were determined.(4) Accordingto the failure mechanism of tunnel surrounding rock deformation, the finite element simulation software MADIS/GTS, a 3D numerical model of tunnel, the distribution of stress, displacement and plastic zone in space and time were studied in the process of tunnel excavation, the comparative analysis of the step height, three-bench seven-step excavation method. Step length, step away from the construction and the construction parameters.and through on-site verification,the construction of the optimized parameters, construction parameters optimized to provide a basis for the deformation control of shallow buried large section tunnel excavation and the safety of rock mass.