Cross-Passage Mining Using Different Supports in Different Grounds

摘要

Cross Passage (CP) mining is a unique form of excavation and there are many ways to skin a cat. In conjunction with the ground improvement such as dewatering, jet grouting, ground freezing and compressed air, different types of initial support can be applied to maintain safe mining. Particularly, CP mining heavily relies on ground conditions and ground improvements therefore the initial support has to be designed accordingly. Through the course of the Project, eight cross passages were excavated along the 6.4 km of twin bored tunnel. Each cross passage had unique ground conditions and different ground support systems were applied at each CP. This paper summarizes our approach on a case by case basis and includes our lessons learned.