Study On Mechanical Behavior And Interaction Of Shallow Buried Large Section Tunnel With Small Net Distance

In order to solve the following problems: topography and geological conditions, traffic congestion, the rigid road line, narrow space, high coverage of areas, high slope, etc., the single hole four-lane arises is developed, with the characteristics of shallow buried super-large section of small clear distance tunnel. For the particularity of the tunnel structure forms and novelty, complex structure, the variable and complicated construction around the hole in the process of mutual influence, the bias effect of tunnel structure, and large cross-section of tunnel excavation, low flat rate and small spacing, no matter from the angle of design and construction, one complete supporting technology has not been formed. What we can do is only expand appropriately in terms of the technical specification for construction of two lanes and three lanes and related engineering experience. There still are a number of key issues to be solved.This study is based on the Quanzhou high rock tunnel, which consists of four parallel paths and in the north-south on the whole. The main line is a single hole with four lanes, and the subordinate line is a single hole with two lanes which consists of a shallow tunnel with large section and small spacing that includes a non-motor vehicle lanes and sidewalks. Based on numerical simulation and field monitoring measurement, the study of construction mechanical behavior and the interrelationship of the 2#, 3# tunnel is carried out. The main research directions are as follows:(1) Relying on the project site collection typical of granite, rock density test and uniaxial compression test, triaxial compression test are performed on standard test specimens(?50mm × 100mm). The integration the basic physical and mechanical parameters of rock can provide basic data for numerical simulation of geotechnical engineering.(2) Based on the different excavation methods and considering the difference in the grade of surrounding rock, 3D models of single hole space are established to analyze the tunnel construction mechanical behavior and deformation characteristics. The relation between the stability of surrounding rock and the excavation time, and by monitoring the measurement results present the feasibility of the numerical analysis. The research findings can be applied to optimize the time of lining construction reasonably and ensure the excavation scheme be safety and the economic efficiency.(3) Besides, one three-dimensional model is constructed to research the mutual influence of two adjacent tunnels, caused by the variation of longitudinal spacing vault settlement, horizontal displacement of rock pillar and stress, etc. From the angle of safety, schedule, economic and other comprehensive consideration, reasonable hole construction constraints around the longitudinal spacing is proposed, which is about 1.0-1.5B, exactly.(4) Furthermore, the project site monitoring measurement study is carried out. Several typical sections are adopted to analyze the stability of deformation on surrounding rock. The feasibility of the numerical simulation and the rationality of parameters of tunneling and the construction scheme are verified. The method proposed in this study can provide early warning function for the whole process of tunnel monitoring during the construction process.