褶皱构造体中深埋隧道岩爆机制与隧道断面适宜性研究

RESEARCH ON ROCKBURST MECHANISM AND PROFILE SUITABILITY OF DEEP-BURIED TUNNEL IN FOLD STRUCTURE BODY

地质构造对岩爆具有重要的影响。以大瑞铁路高黎贡山深埋隧道为工程实例,在野外地质调查、岩石力学测试分析、地应力测试分析等研究基础上,采用ANSYS大型有限元数值软件模拟分析在现今构造应力场中,在褶皱构造带岩体中开挖隧道所引起的隧道围岩应力重分布特征,对不同工况组合条件下深埋隧道的岩爆特征进行深入分析和研究,并就可能发生岩爆的部位和岩爆强度进行预测。研究表明,岩爆发生强度与隧道所在地质构造体中的不同部位和隧道形状具有较大关系:当马蹄形隧道位于向斜核部、圆拱直墙形隧道位于背斜核部和褶皱翼部且隧道轴线与褶皱轴线相平行时发生岩爆的可能性最大,而当隧道轴线与褶皱轴线相垂直时发生岩爆的可能性较低。隧道规划建设宜选择在隧道轴线与褶皱轴线相垂直等部位,或当隧道轴线平行于褶皱轴线时选择适宜性较好的隧道断面,以减弱岩爆对隧道工程的影响。

Geological structures have some important effects on rockbursts. Taking the deep-buried Gaoligong Mountain tunnel for example, based on field geological investigation, laboratory rock mechanical tests and geostress measurements, adopting the finite element software ANSYS, stress redistribution of the tunnel surrounding rocks, which is induced by tunnel excavation, is analyzed under current geostress. The rockburst characters of the tunnel are also deeply investigated under different case combinations, and possible rockburst positions and intensity are predicted. The results indicate that the rockburst intensity has some relations with the position in the geological structure body where the tunnel is located, as well as the tunnel profile. Namely, the rockburst is prone to happen mostly when the tunnel axis is parallel to the fold axial line and the horseshoe tunnel is located at synclinal-shaff, or the circular arch-vertical wall tunnel is located at the anticlinal-shaft and fold limb department; but when the tunnel axis is vertical to the fold axial line, the possibility ofrockburst is small. During tunnel planning and construction, the position where the tunnel axis is vertical to the fold axis, or more suitable tunnel profile, should be selected, which is advantageous for weakening the influence of rockbursts.