On the feasibility of TBM drives in squeezing ground

Abstract

Squeezing ground may cause a series of difficulties such as sticking of the cutter head or the shield, extensive convergences of the bored profile or destruction of the tunnel support. In very soft rock, clogging or sagging of the cutter head may also occur, and TBM bracing by the gripper plates may become impossible. These difficulties, alone or in combination with instabilities of the tunnel face and walls, may slow down or even obstruct TBM operation and, if occurring over frequent tunnel intervals or persisting over longer portions of a tunnel, may have a decisive effect on the feasibility of a TBM drive. This paper discusses the specific problems of mechanized tunneling in squeezing ground, investigates the problem of shield jamming and analyses the effects of possible countermeasures, on the basis of the results of numerical computations.(A) This paper was presented at Safety in the underground space - Proceedings of the ITA-AITES 2006 World Tunnel Congress and the 32nd ITA General Assembly, Seoul, Korea, 22-27 April 2006. For the covering abstract see ITRD E129148. Reprinted with permission from Elsevier.