Abstract The mechanical behaviors of shallow bias tunnels with small clear distances in different geological conditions are quite different. In half-soft and half-hard rock especially, rock stability at the interface of the soft and hard rock will be disturbed by tunnelling and is characterized by very special mechanical behaviors. In this paper, tunnel excavations in 15 different conditions are simulated by applying the finite difference software FLAC3D to analyses of crown settlement, middle-wall horizontal displacement, middle-wall maximum principle stress, and the plastic zone of rock for tunnels with different clear distances in homogeneous hard rock, homogeneous soft rock, and half-soft and half-hard rock. The results show that: tunnel crown settlement is minimized in the homogeneous hard rock, similar for the half-soft and half-hard rock, and maximized in soft rock; for the tunnel in the half-soft and half-hard rock, the rock-mass stability is poor at the upper part of the rock pillar, and horizontal displacement reaches a maximum at the middle part; and stability of the overlying rock of the cavern at the soft-rock side is worsened and may result in collapse.
Abstract：
The mechanical behaviors of shallow bias tunnels with small clear distances in different geological conditions are quite different. In half-soft and half-hard rock especially, rock stability at the interface of the soft and hard rock will be disturbed by tunnelling and is characterized by very special mechanical behaviors. In this paper, tunnel excavations in 15 different conditions are simulated by applying the finite difference software FLAC3D to analyses of crown settlement, middle-wall horizontal displacement, middle-wall maximum principle stress, and the plastic zone of rock for tunnels with different clear distances in homogeneous hard rock, homogeneous soft rock, and half-soft and half-hard rock. The results show that: tunnel crown settlement is minimized in the homogeneous hard rock, similar for the half-soft and half-hard rock, and maximized in soft rock; for the tunnel in the half-soft and half-hard rock, the rock-mass stability is poor at the upper part of the rock pillar, and horizontal displacement reaches a maximum at the middle part; and stability of the overlying rock of the cavern at the soft-rock side is worsened and may result in collapse.
QI Han-1,
Gao-Bo-1,
Wang-Shuai-Shuai-1 etc
.Mechanical Behaviors of a Shallow-Bias Tunnel with a Small Clear Distance in Different Geological Conditions[J] MODERN TUNNELLING TECHNOLOGY, 2014,V51(4): 108-112
2014, Vol. 51 