深埋隧道穿越富水破碎带围岩突水机理

来源期刊:中南大学学报(自然科学版)2016年第10期

论文作者:李廷春 吕连勋 段会玲 陈伟

文章页码:3469 - 3477

关键词:深埋隧道;岩体;断层破碎带;突水机理;流固耦合

Key words:deep buried tunnel; rock mass; fault fracture zone; water inrush mechanism; fluid-solid coupling

摘    要:基于隧道穿越处于复杂应力场与渗流场环境的富水破碎带时存在发生重大突水事故的安全隐患,通过对破碎岩体的渗流特点进行研究,建立孔隙颗粒介质流失的渗流模型;基于连续介质力学和变质量动力学理论,推导饱和破碎岩体变质量渗流-变形耦合理论模型;以福建漳州梁山隧道L7富水破碎带为工程背景,分析围岩的渗流场、应力场与位移场分布特性,并总结隧道断层破碎带的突水塌陷机理。研究结果表明:断层破碎带突水实质上是围岩的力学平衡和地下水的渗流平衡因施工扰动发生急剧变化,引起围岩应力重分布及地下水能量释放;隧道施工揭露断层后,岩体颗粒随孔隙空间的流体发生迁移形成新的渗流通道,导致地下水在水头压力作用下向工程临空面涌出,形成漏斗形的渗水区域;随着渗流作用时间的延长,地下水和岩土体逐渐流失,隧道上方的破碎岩体发生严重的滑移变形,形成椭圆形塌陷区域,与现场实际塌陷破坏规律基本吻合。本文提出的渗流-变形耦合模型对理解破碎岩体渗流力学机制和深埋隧道突水灾害的预防设计具有参考价值。

Abstract: Considering that there will be security risk of inrush accident when tunnel passes through the weak water-rich zone with complex underground stress field and seepage field environment, a seepage model of porous medium was established through the research of the seepage characteristics of broken rock mass. And theoretical model of fluid-solid coupling of saturated broken rocks was deduced based on the theory of dynamics of variable mass and continuum mechanics. Taking the L7 weak water-rich zone of the Liangshan Tunnel in Zhangzhou, Fujian Province, as engineering background, the distribution features of stress field, seepage field and displacement field of the surrounding rock were analyzed, and inrush collapse mechanism of the fault fracture zone was summarized. The results show that water inrush is actually caused by the stress distribution of surrounding rock and energy release of the groundwater, which results from the dramatic change of mechanical equilibrium of rock mass and seepage balance of the groundwater for construction disturbance. When the fault is exposed, rock particles loss in the pore space to form new seepage channel, leading to welling of groundwater under the pressure of water head to form funnel-shaped water seepage area. With the increase of the seepage time, groundwater and rock mass experience gradual loss and the fractured rock mass on the top of tunnel have serious slip deformation, forming oval subsidence area. This conclusion basically coincides with practical situation. The fluid-solid interaction model proposed has high practical significance to understand the seepage mechanics and prevention design of deep buried tunnel water inrush disaster.

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