Abstract
This is the report of an experimental study on the stability of tunnel face driven by shield, including the “caving phenomenon”.
The caving is called the initial slip failure of ground along the face produced by the cutter disk of shield. From the results of experiments, the followings are summed up: (1) the caving occures prior to the general failure of the face ahead of the shield. (2) The ground strength necessary to prevent caving is larger than that necessary to prevent general failure (3) the larger the diameter of shield, the greater the ground strength is needed to prevent caving.
