非匀质砂层钻孔桩孔壁稳定性和施工工艺优化研究

Research on Hole Wall Stability and Optimization of Construction Technology of Bored Pile in Inhomogeneous Sand Layer

为解决非匀质砂层地质条件下大直径超长桩基施工中存在的塌孔等问题,依托西安地铁10号线一期工程跨泾河大桥工程项目,提出了旋挖钻机与反循环钻机相结合的施工工艺,保证了桩基质量和施工进度,同时通过理论研究与现场试验相结合建立了孔壁稳定性模型,分析了孔壁土体临界受力状态,通过构建泥浆参数与孔壁临界受力的联系得出了不同地层的最优泥浆重度,为孔壁稳定性施工提供了理论依据,对孔位偏差、钢筋笼连接、二次清孔以及水下混凝土灌注工艺进行了优化分析,为相关工程提供了参考与借鉴。

In order to solve the problems of hole collapse during the construction of large diameter and ultra long pile foundations under inhomogeneous sand geological conditions,phase I project of Jinghe river bridge of Xi'an metro line 10 is taken as an example.A construction technology combining rotary drilling and reverse circulation drilling is proposed to ensure the quality and progress of pile foundation construction.At the same time,a hole wall stability model is established and the critical stress state of the hole wall soil is analyzed through combining theoretical research with on-site experiments.The optimal mud ratio for different strata is obtained by constructing the relationship between mud parameters and the critical stress on the hole wall.It provides a theoretical basis for the stability construction of the hole wall,optimization analysis for the hole position deviation,reinforcement cage connection,secondary hole cleaning,and underwater concrete pouring process.It provides reference for related projects.