Abstract: As a type of weak rock mass with unique engineering properties, mudstone swells, softens and even disintegrates after absorbing water, resulting in a significant decrease in mechanical strength, which seriously affects the safety and stability of tunnel. Existing research on the stability of mudstone tunnels has ignored the redistribution of the water field of mudstone tunnels during the process of construction and operation and lacked consideration of the combined effects of swelling and softening of mudstone after water immersion on the stability of tunnels. Taking a certain under-construction tunnel of the Lanzhou-Hezuo Railway as the engineering background, a seepage-stress coupling model of mudstone tunnel was constructed by combining on-site moisture monitoring and lining disease investigation data. The distribution characteristics of the water field in the surrounding rock were analyzed, the spatiotemporal evolution characteristics of the dynamic response of lining stress and the expansion of the plastic zone were revealed, and the influence and contribution of mudstone swelling and softening effects on tunnel displacement changes and overall stability were explored. The research conclusions can provide theoretical basis and method reference for revealing the deformation mechanism of mudstone tunnels and proposing technical countermeasures for prevention and control.

Key words: tunnel engineering; railway engineering; mudstone tunnel; stability; swelling; softening; seepage-stress coupling model

摘要： 作为一种工程性质特殊的软弱岩体，泥岩吸水后会发生膨胀、 软化甚至崩解，导致力学强度大幅度下降，从而严重影响隧道工程的安全与稳定。现有对泥岩隧道稳定性的研究忽略了泥岩隧道在施工或运营过程中水分场的重分布，也缺乏考虑泥岩浸水后膨胀及软化共同作用对隧道稳定性的影响。以兰州至合作铁路某在建隧道为工程背景，结合现场水分监测和衬砌病害调查数据，构建了泥岩隧道渗流-应力耦合模型，系统分析了围岩水分场的分布特征，揭示了衬砌应力动态响应及塑性区扩展的时空演化特征，探索了泥岩膨胀与软化效应对隧道位移变化及整体稳定性的影响程度与贡献度。研究结论可为揭示泥岩隧道变形机理和提出防控技术策略提供理论依据和方法借鉴。

关键词: 隧道工程；铁道工程；泥岩隧道；稳定性；膨胀；软化；渗流-应力耦合模型