Research On The Key Technology Of City Hard Rock Overlapping Tunnel Construction

In recent years, with the rapid economic development of Chongqing City, the population, the number of vehicles is increasing, city traffic congestion problems have become increasingly prominent. City subway construction is the effective measure to alleviate traffic pressure in the city, along with the continuous development of the construction of city subway, city subway tunnels are often forced to use overlapping tunnel, so small spacing tunnel overlap is often seen. Considering the characteristics geological of Chongqing city is horizontal layered rock, combined with the structure characteristics of the project-the super small-distance overlap structure, at the same time, according to the characteristics of city subway construction environment of existing buildings in dense distribution and personnel mobility, and comprehensive DaLongsan station interval tunnel construction method and construction situation, the research of this paper from the following aspects:(1) study on failure mechanism and mode of the thick horizontal layered rock closely-spaced overlap tunnel under blasting vibration, the application of numerical analysis based on and after the first, after first under two construction time single, double open to the surrounding rock falls, cracking, slip and level level comprehensive analysis, get place an order, thick horizontal layered rock conditions of single,double tunnel failure modes and failure characteristics.(2) in the thick horizontal layered rock closely-spaced research on key technology of overlap tunnel construction, combined with the Chongqing metro line six, on and after the first, the first after the two excavation sequence, whole section, two kinds of construction methods and steps were performed full-face excavation step hole excavation, failure mode displacements of surrounding rock, surrounding rock stress, the plastic zone of the surrounding rock, comparison results of internal force of support structure and construction safety comprehensive analysis of surrounding rock, combined with the construction of economy, convenience and other factors to consider, finally obtained the construction method of excavation, and the best timing has row hole excavation step.(3) in the thick horizontal layered rock closely-spaced overlap tunnel construction research of interaction between, on the overlap, oblique45degrees, three horizontal parallel spatial relationship with different distance under the condition of horizontal, longitudinal tunnel construction influence the results of studying the rules and characteristics based on the surrounding rock stress, and comprehensive evaluation, the initial support internal partition criteria and classification standard, the transverse, longitudinal effects of double tunnel construction partition range.(4) TBM by the thick horizontal layered rock with small spacing affect the safety of overlapping tunnel structure research, based on the TBM through the tunnel lining structure analysis of two security, the TBM through the tunnel, the tunnel lining, two transverse longitudinal influence area and in the strong influence within the scope of the reinforcement measures, at the same time according to the field monitoring results, the TBM through the tunnel, the tunnel structure in a safe state, and also verified the reinforcement measures of recommended structure of science and rationality.(5) study the impact on the surrounding environment and construction blasting vibration control technique, combining the research data of standard on the surrounding environment vibration blasting construction, including the influence of building structure safety and personnel psychology two aspects, and gives the standard range of motion control measures.