Research on TBM Construction Technology of Small Clearance Crossing of Existing Track Lines at Soft and Hard Rock Interfaces

With the rapid development of urban rail transit, the municipal rail line network has shown a trend of complexity and densification, and the engineering construction conditions have become more and more complex, but due to the limitation of construction cost and geological topography, the design and planning spacing of some lines is extremely small, and the construction of the later tunnel may have a certain impact on the safe operation of the existing operation line. This paper takes the small clearance (structural clearance 3 m, excavation contour line and primary bolt clearance 15 cm) crossing the existing operation Line 9 at the interface of the upper soft and lower hard rock layer at the interface of the upper soft and lower hard rock layer in the middle of Chongqing Rail Transit Line 18 North Extension Project ~ end point, and theoretically analyzes the adverse effects of crossing construction under extreme working conditions. Through the development of targeted construction control measures, to ensure that the settlement and scope can be controlled within the effective range, and with the help of automatic monitoring means, to lay the foundation for smooth through the construction.