巨型溶洞回填体内桥梁隧道高效施工技术

Efficient Construction Technology of Bridge and Tunnel in Backfill of Giant Karst Cave

成贵铁路玉京山隧道穿越一处巨型溶洞,溶洞空腔体积巨大、洞壁不稳定、水文地质条件复杂;隧道穿越溶洞段长约86 m,高悬于溶洞顶板附近,距离溶洞底部堆积物顶面约40~45 m。该溶洞处置方案复杂,施工安全风险高、工期紧。针对溶洞回填体中暗挖隧道和隧道内桥梁部分,通过开展回填体注浆加固、隧道“五台阶设钢管临时横撑法”开挖支护、桥隧“先桥梁支架现浇、后隧道二次衬砌”综合施工等施工技术研究,实现了超大断面暗挖隧道施工安全和桥隧高效施工,取得了良好的工程效果,确保了项目按期建成通车运营。

Yujingshan Tunnel of Chengdu-Guizhou Railway passes through a giant karst cave which has huge cavity volume,unstable cave wall and complex hydrogeological conditions.The tunnel crossing karst cave is about 86 m long,hanging near the roof of karst cave,and its distance is about 40-45 m away from the top surface of deposits at the bottom of karst cave.The karst cave disposal scheme is complex,with high construction safety risk and short construction period.In view of the excavated tunnel and the bridge in the tunnel in the karst cave backfill,by carrying out research on the construction technology,such as grouting reinforcement of backfill,excavation and support of“temporary cross bracing method with steel pipes at five steps”,and comprehensive construction of bridge and tunnel,such as“first cast-in-place bridge bracket,secondary lining of tunnel later”,the construction safety of the super-large cross-section excavated tunnel and efficient construction of bridge and tunnel have been realized,and good engineering results have been achieved,ensuring that the project is completed and opened to traffic on schedule.