隧道开挖面接近地质界面时围岩位移特征及其影响因素分析

Displacement Characteristics of the Surrounding Rock and the Influencing Factors Analysis when Tunnel Excavating towards the Geological Interface

用FLAC3D分析隧道开挖面接近地质界面时隧道围岩变形行为以及侧向应力、纵向应力、洞室形状、地质界面倾角对隧道围岩位移的影响规律。结果表明:当隧道由硬岩向软岩掘进时,随着开挖面逐渐接近前方地质界面,隧道拱顶和边墙位置围岩的位移均有明显的增加;当隧道由软岩向硬岩掘进时,开挖面以及开挖面前方的拱顶和边墙位置围岩的位移均有明显的减小;隧道掘进至硬岩与软岩的地质界面,隧道边墙位置围岩径向位移随侧向应力的增加而增加,拱顶和边墙位置围岩的纵向位移随纵向应力的增加而增加;矩形隧道时围岩的位移最大,马蹄形隧道时次之,圆形隧道时最小;地质界面倾斜时围岩的位移均比地质界面垂直时大。

The deformation behavior of the surrounding rock has been analyzed by FLACaD when tunnel excavating towards the geological interface, and the influencing factors such as the lateral stress, longitudinal stress, cavern shape, the inclination of geological interface have also been studied. The calculation results show that the displacements of the surrounding rock of the crown and the side wall increase obviously when tunnel excavating toward the geological interface from hard rock to soft rock. On the contrary, the displacements of the surrounding rock of the crown and the side wall around and ahead the excavation face will decrease apparently when tunnel excavating toward the geological interface from soft rock to hard rock. When tunnel is excavating toward the geological interface of soft and hard rock, the radial displacement of the surrounding rock of the side wall increase with the increasing of the lateral stress, and the longitudinal displacements of the surrounding rock of the crown and the side wall will increase with the increasing of the longitudinal stress. The displacement of the surrounding rock of hoof--like tunnel is smaller than that of the rectangular tunnel, and the displacement of surrounding rock of circular tunnel is the smallest. The displacement of the surrounding rock will be larger when the geological interface is oblique than when is vertical.