折线形布桩在某地下停车库深基坑中的应用

Application of the Staggered Soldier Pile Layout in Supporting a Deep Excavations of an Underground Parking Garage

排桩+混凝土内支撑的围护结构在基坑设计中应用广泛。排桩多采用直线布置,虽施工方便,但是支护刚度难以满足大型基坑施工设计要求。以武汉某地下车库深大基坑为研究背景,首先利用有限元数值计算分析比较了折线形布桩与常规直线形布桩下,桩体水平位移随开挖过程的变化规律。结合工程的实际情况,提出了排桩折线布置形式和设计参数。现场应用效果和数值仿真结果的对比分析表明,当排桩采用折线布置时,围护结构的最大水平位移为3.8 mm,出现在墙体中部,满足变形控制要求,验证了折线型布桩的合理性,可以为类似工程设计提供参考。

The soldier pile lagging with concrete internal strut is a common supporting structure in the deep excavation.Most of the soldier pile supporting structures have a straight-line layout due to their simplicity and the construction convenience,however,the stiffness of the straight-line layout has difficulties meeting the requirements of supporting large excavations.This paper presents a case history of a large sized deep excavation supporting design for an underground parking garage in Wuhan.the horizontal deflection at the pile head during the progress of the excavation of both the staggered and straight-line soldier pile layouts are numerically analyzed and evaluated.The design parameters and optimized layout for the staggered soldier pile supporting structure are proposed based on the site-specific subsurface conditions.The comparison of the construction monitoring and numerical simulation results indicates that,the maximum lateral deflection in the staggered soldier pile supporting is 3.8 mm and is located at the middle of the exposed supporting structure.The lateral deflections in the staggered soldier pile wall meet the design requirements.