排水结构设置后软岩隧洞的渗流-应力耦合分析

高外水作用下,深埋软岩隧洞围岩-支护结构安全将受到极大挑战。为了降低高外水压对软岩隧洞围岩-支护体系的影响,较常见的工程处理措施为在隧洞周围布置排水结构,以降低洞周外水压力。笔者首先提出了一种简便的隧洞围岩-衬砌结构渗流-应力分析思路。然后,以某过断层带深埋软岩隧洞为研究对象,通过开展隧洞施工期、运行期渗流-应力耦合分析,研究了软岩隧洞排水结构的排水效应。研究发现,在注浆圈和排水结构的综合作用下,隧洞衬砌附近的水力比降较小,注浆圈水力比降较大,使注浆圈承担绝大部分外水荷载,而衬砌承担少部分外水荷载;在软岩和衬砌的变形协调作用下,最终形成注浆圈与衬砌的协同承载效应,有效提高了隧洞的运行安全水平。

Seepage-Stress Coupling Analysis of Soft Rock Tunnel with Drainage Structure

The safety of surrounding rock and support structures of deep-buried soft rock tunnel is faced with great challenges under the action of high external water pressure. Drainage structure is a common engineering treatment to alleviate the impact of external water pressure on the surrounding rock and support structure of soft rock tunnel. A simple seepage-stress coupling scheme for tunnel’s surrounding rock-lining structure is first established. The drainage effect of the drainage structures of a deep-buried soft rock tunnel crossing a fault zone is investigated through seepage-stress coupling analysis in construction period and operation period. Under the combined action of grouting ring and drainage structures, the hydraulic gradient near tunnel lining is small while the hydraulic gradient of grouting ring is large. As a result, the grouting ring bears most of the external water load, while the tunnel lining bears a small part of the external water load. In addition, under the deformation compatibility between soft rock and lining, the co-bearing effect between grouting ring and lining is finally formed, which effectively improves the safety of the tunnel in operation period.