过江泥水盾构成功穿越正交断裂带经验总结与对工程勘察设计的启示

Experience Summary of Cross-river Slurry Shields in Successfully Crossing Orthogonal Fault Zones and Its Implications for Engineering Survey and Design

摘要:

针对正交断裂带地质条件复杂、易引发盾构滞排及江中冒浆等险情。以某城市轨道交通区间过江泥水盾构穿越2条正交断裂带交汇处的施工为例，通过采取加密施工勘察勘探点间距（间距1.5 m）以获取工程地质信息、优化泥浆性能（比重提升至1.26）以提升泥浆携块石能力、实施破碎地层预注浆加固、开仓清理滞排石块等综合技术措施，使得盾构成功穿越了断裂带，系统性地控制了施工风险，并验证了采取加密施工勘察和综合技术措施的有效性。建议针对盾构法隧道特殊性，应优化勘察规范，减小极复杂场地勘探点间距；重新评估在断裂带地层RQD值对盾构法隧道围岩质量的适用性；提高设计阶段风险等级，增加江中注浆预加固等辅助措施，必要时调整隧道线路以避让断裂带，降低施工风险。

Abstract:

In view of the complex geological conditions of the orthogonal fault zone, which is prone to cause dangerous situations such as shield stagnation and slurry gushing in the river, taking the cross-river construction of a slurry shield machine crossing the intersection of two orthogonal fault zones in an urban rail transit section as an example, the comprehensive technical measures of increasing the spacing of construction survey and exploration points (1.5 m spacing) to obtain engineering geological information, optimizing the slurry performance (proportion increased to 1.26) to enhance the slurry ability to carry boulders, executing pre-grouting reinforcement of fractured strata, opening chamber to clear the stagnant stones are taken to make the shield successfully cross the fault zones, and systematically control the construction risks. And the effectiveness of increasing the construction survey and the integrated technical measures is verified. It is recommended to optimize the survey specifications and reduce the spacing of exploration points in extremely complex sites for the particularities of shield tunneling. The applicability of the RQD value in the fault zone strata to the surrounding rock quality of shield tunneling is re-evaluated. The risk levels in design phase are elevated. The auxiliary measures of pre-reinforcement by grouting in the river are added. When necessary, the tunnel route is adjusted to avoid the fault zone and reduce the construction risk.