侵蚀环境中浅埋隧道管片衬砌的承载性状

Bearing Behavior of Segmental Lining of Shallow-Buried Tunnel in Erosive Environment

摘要: 本文针对侵蚀环境中盾构隧道管片衬砌的承载性状展开研究，基于数值模拟，系统探讨了管片被侵蚀之前、管片表层的承载能力丧失后、管片表层出现洞穴后、江水能够顺畅地侵入至管片表层四个不同阶段下对衬砌环整体及局部受力性状的影响规律。研究结果表明：位于衬砌环顶部的管片侵蚀会引发结构非对称变形，导致拱顶与拱底沉降持续增大，且水平位移在环向特定区间内发生定向偏移；在江水侵入管片表层后，水平最大错动位移发生位置改变，且位移量增大约50%；侵蚀洞穴导致洞穴位置靠近围岩一侧出现明显的拉应力集中，而围岩压力集中位置则表现为压应力翻倍；靠近围岩一侧以弯曲拉应力主导，导致该处在洞穴中心的最小主压应力低于围岩压力集中处；靠近净空一侧则因弯曲压应力较强，呈现相反规律。基于上述结果，本文提出建议：在运营维护中应实施差异化监测，重点关注被侵蚀管片、接缝及应力集中区域；对异常部位采取局部加固，并加强管片间连接螺栓的防腐检测与防护。本研究结果可为类似侵蚀环境下盾构隧道的状态评估、运营维护提供理论参考。

Abstract: This study investigates the bearing behavior of shield tunnel segment lining in erosive environments. Based on numerical simulations, a systematic investigation was conducted on the influence patterns of four distinct stages—namely, before segment erosion, after the loss of bearing capacity at the segment surface, after cavity formation on the segment surface, and after river water freely penetrates to the segment surface—on both the overall and local mechanical behavior of the lining ring. The results indicate that erosion at the crown of the lining ring induces asymmetric structural deformation, leading to continuous increases in crown and invert settlement, along with directional shifts of horizontal displacement within specific circumferential intervals. After river water intrudes into the segment surface, the location of the maximum horizontal dislocation displacement changes, with its magnitude increasing by approximately 50%. Erosion-induced cavities cause significant tensile stress concentration on the surrounding rock side near the cavity, while the pressure concentration zone in the surrounding rock exhibits a doubling of compressive stress. On the surrounding rock side, bending-induced tensile stress dominates, resulting in a minimum principal compressive stress at the cavity center that is lower than that at the surrounding rock pressure concentration zone. Conversely, on the clearance side, stronger bending-induced compressive stress leads to the opposite trend. Based on the findings, this paper proposes that differentiated monitoring strategies should be implemented during operation and maintenance, with particular attention to eroded segments, joints, and stress concentration zones. Local reinforcement should be applied to abnormal areas, and anticorrosion inspection and protection of connecting bolts between segments should be enhanced. The results of this study can provide theoretical references for condition assessment, operation, and maintenance of shield tunnels in similar erosive environments.