高速铁路隧道塌方原因分析与施工处治技术

Analysis on the Causes of High-speed Railway Tunnel Collapse and the Dealing Construction Technology

摘要:

结合某高速铁路隧道DgK88+520～522段施工出现掌子面附近拱顶塌方的工程背景，从现场地质条件与设计支护参数等方面分析了塌方原因，并采用数值模拟对比分析了勘查设计与围岩变更后的开挖支护措施引起的围岩变形。结果表明，根据原勘查设计Ⅲa级围岩确定的开挖方法与支护参数不能有效保证实际围岩条件下的隧道稳定性，而采用围岩变更为Ⅴb级围岩、三台阶七步法开挖、Ⅴb级围岩复合式衬砌支护的设计，拱顶沉降则可大幅度降低。介绍了塌方处治措施和拱顶沉降监测结果。由于围岩表现为脆性，在塌方后拱顶沉降较小，为确保工程安全，应根据地质勘查与超前地质预报等辅助措施，更为准确地掌握隧道围岩地质赋存条件，确定合理的开挖方法与支护参数。

Abstract:

According to the vault collapse near tunnel face occurred at the section DgK88 520～522 of a high-speed railway tunnel, the analysis is made on the collapse causes in site geological conditions and designed supporting parameters, and the comparative analysis is also made by numerical simulation on the exploration design and surrounding rock deformation caused by excavating and supporting measures. The result showed that the design, which was based on Ⅲa surrounding rock by original survey, of excavation method and support parameters couldn't guarantee the tunnel stability under the actual surrounding rock conditions, while with the design of 3-step and 7-process excavating method and composite lining support for Ⅴb surrounding rock, crown settlement was drastically reduced. The paper introduces the dealing method for collapse and the monitoring result of crown settlement. Due to the brittleness of surrounding rock, the crown settlement is light after collapsing. To ensure the safety of the construction project, geological occurrence conditions of tunnel surrounding rock should be grasped more accurately based on the geological survey and geological forecast to decide reasonable excavation method and support parameters.