Construction method of work pit intersection in mountain tunnel construction

摘要

PROBLEM TO BE SOLVED: To construct a work pit intersection in a mountain tunnel construction capable of effectively reinforcing the ground of an intersection connected to a work pit which is an excavation area where cracks and collapses are likely to occur at a planned construction site of the main pit. I will provide a. In the intersection work space forming step, a plurality of work pit widening portion steel support members 15a to 15j having a height exceeding the arch-shaped portion 14a of the tunnel main pit 14 are installed along the excavation inner wall surface. The intersection widening work space portion 17 is formed. In the process of forming the main tunnel at the intersection, one end of the work area inside the installed work pit widening portion steel support members 15a to 15j is supported by the gantry pedestal 18, and the intersection is made of steel for the main pit. A plurality of support members 19, 19'are installed, and sprayed concrete is sprayed to form the intersection tunnel main pit 20. The tunnel main pit 14 will be constructed on the planned extension line 13 with the intersection tunnel main pit 20 as the excavation start base 12 for the main pit. [Selection diagram] Fig. 2