富水砂卵石地层盾构隧道长距离穿越机场飞行区技术研究

为确保国内首次在富水砂卵石地层长距离下穿机场飞行区，以及成都地区首次采用冻结法实施联络通道的隧道工程顺利实施，通过工程类比、专家论证、优化设计、数值计算与现场监测数据分析相结合等手段，提出长距离隧道整体工程筹划优化设计、盾构配置优化、克泥效工法、陆地声呐法空洞探测、联络通道预注浆与冻结法复合截水等一系列组合技术措施。实践结果表明： 1）采用盾构工法，优化线路平、纵断面设计，增设中间风井以大幅减少盾构单次掘进距离至1 km左右，并辅以严格的沉降控制组合措施等，可以成功解决富水砂卵石地层长距离下穿机场飞行区的重大技术难题； 2）本工程提出的先在洞内使用双液浆注浆预堵水，再采用冻结法加固的复合截水方案，在富水砂卵石地层可以达到良好的截水效果。

Technology for Long distance Shield Tunnel Crossing Airport Area in Water rich Sandy Cobble Strata

In order to ensure the implementation of the first long distance shield tunnel crossing underneath airport area in water rich sandy cobble strata in China, as well as connection gallery of tunnel project by freezing method in Chengdu, measures, i.e. project comparison, expert demonstration, design optimization, numerical calculation and field monitoring data analysis, are adopted, and a series technical measures, i.e. optimization design of overall engineering planning, optimization of shield configuration, clay shock method, land sonar cavity detection, pre grouting for connection gallery and water stop by of freezing method, etc., are put forward. The practical results show that: (1) Major technical problems of long distance shield tunnel crossing underneath airport area in water rich sandy cobble strata can be successfully solved by using shield construction method, optimizing the horizontal and vertical cross section design, adding a middle ventilation shaft to greatly reduce the single driving distance of shield to about 1 km, and adopting strict settlement control measures. (2) The composite water stop scheme proposed, i.e. water stop in tunnel by double grouting + freezing reinforcement, can achieve good effect in water rich sandy cobble strata.