Key Technology of Inclined Shaft into Main Tunnel Roof-jacking Construction in Adjacent Fracture Zone Stratum
Aiming at the problems of complex stress and difficult control of deformation in the construction section of the main tunnel caused by the stratum adjacent to the fracture zone of the tunnel inclined shaft,taking the roof-jacking construction at the intersection of the No.1 inclined shaft and the main tunnel of Xigu Tunnel as the research object,the detailed super-scheme front support,monitoring and measurement scheme and deformation control scheme are formulated,and the roof-jacking construction method of the double-lane inclined shaft into the double-hole single-line tunnel adjacent to the fracture zone stratum is proposed.The rationality and feasibility of the method are evaluated by finite element simulation method.The results show that the stability of surrounding rock can be guaranteed by using the method of small pipe advance support and step method to pick the top into the main tunnel in the adjacent fracture zone at the intersection.The setting of reinforced support can effectively solve the problem of surrounding rock deformation caused by the large section size of inclined shaft and main tunnel.There is a stress relaxation zone in the surrounding rock of the vault of the intersection section.This method uses a close-packed portal frame to enhance the tunnel support,which not only fits the excavation contour of the main tunnel well,but also ensures the operation safety and excavation progress.
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