针对近年来城轨交通地下工程周边地表频繁塌陷的实际情况，建立地表下方空洞理论模型。通过实际工程案例分析与理论分析相结合的手段，对城轨交通周边地表坍塌原因、塌陷过程与机制、主要应对措施等方面进行研究，揭示城轨交通地下工程建设与管网渗漏、地表坍塌之间的内在联系，并给出有效应对措施。研究发现： 1）城轨交通工程周边地表突然坍塌存在3种典型工况，即管网渗漏、施工降水和地层损失沉降； 2)地下工程建设引起的地层沉降与周边管网渗漏之间存在相互促进关系，地下管网渗漏引起的地层冲刷与沉降变形主要集中在地表至管底以下1~2 m； 3）明确地表坍塌过程及塌陷机制，提出地表突然塌陷的临界脱空区范围理论模型，当脱空区长度达1.6 m时地表将存在塌陷风险； 4）通过参数敏感度分析明确提高地表道路结构层强度为相对经济且有效的预防措施，从主动控制与被动防御2个方面提出防止地表坍塌的应对措施。

In recent years, frequent surface collapse phenomena have been observed around underground engineering works in rail transit projects. To prevent such occurrences, a theoretical model for calculating the extent of cavities beneath the ground surface is established, and a corresponding theoretical formula is derived. The causes, processes, and mechanisms of ground collapse, along with countermeasures, are analyzed through both practical and theoretical approaches, revealing the internal relationships among underground rail transit construction, pipeline leakage, and surface collapse. The results show that: (1) Sudden surface collapses around underground engineering works in rail transit projects are primarily induced by pipeline leakage, dewatering operations, and ground loss settlement. (2) Ground settlement is positively correlated with leakage from surrounding pipelines, with erosion and settlement deformation mainly concentrated from the ground surface to 1－2 m beneath the pipe bottom. (3) The process and mechanism of surface collapse are clarified, and a theoretical model for the critical void zone of sudden collapse is proposed—a collapse may occur when the void length reaches 1.6 m. (4) Improving the strength of road structures is a relatively economical and effective preventive measure, based on sensitivity analysis of key parameters. Effective countermeasures are proposed from the perspectives of both active control and passive defense.