Deformation, Failure and Stability of Tunnels in Squeezing Rocks

A distinguishing feature of tunnels in squeezing rocks is that a large deformation of the surrounding rocks takes place slowly and gradually, often called squeezing phenomenon. It is different from the rocksbursting phenomenon during which the deformation of tunnels occurs instantaneously when the resulting stresses exceed the strength of the surrounding rocks. The squeezing phenomenon has received great attention in the field of rock mechanics and tunnelling recently. The mechanism and various factors related to the large deformation and failure of tunnels in squeezing rocks are discussed in this paper on the basis of field investigations and laboratory model tests. The relationship between the deformation of surrounding rocks and support of the tunnels in squeezing rocks is presented in the form of numerical modelling.