既有公路桥下方隧道深基坑综合施工技术

Comprehensive Construction Technology of Deep Foundation Pit of Tunnel below Existing Highway Bridge

为解决在既有公路桥下方施工空间受限条件下隧道深基坑施工难题,通过自主研发在下穿桥梁基坑支护的基础上与既有桥梁下部结构加固钢支撑及隧道底板以下加固土体形成一体化支撑,对既有桥梁桩基周围土体采用低扰动加固,在施工空间受限条件下采取对称开挖传递出土的综合施工技术,提高基坑结构整体性和安全系数及既有桥墩周边土体的固结、止水质量,减少打桩施工及基坑开挖过程中对既有桥墩桥台及桩基础的偏压影响,保证既有桥梁结构和运营安全。

In order to solve the construction problem of deep tunnel foundation pit under the condition of limited construction space under the existing highway bridge,through independent research and development,on the basis of the foundation pit support of the underpass bridge,the steel support of the substructure of the existing bridge is strengthened and the soil body is strengthened below the tunnel floor.Form integrated support,adopt low-disturbance reinforcement for the soil around the existing bridge pile foundation,and adopt the comprehensive construction technology of symmetrical excavation and transfer excavation under the condition of limited construction space,so as to improve the structural integrity and safety factor of the foundation pit and the existing bridge piers.The consolidation and water-stop quality of the surrounding soil can reduce the impact of eccentric pressure on the existing bridge piers,abutments and pile foundations during the process of piling construction and foundation pit excavation,and ensure the existing bridge structure and operation safety.