深基坑吊脚桩支护结构设计优化与变形特性分析

Structural Design Optimization and Deformation Characteristics Analysis of End-suspended Piles of Deep Foundation Pit

以青岛某深基坑工程为例,应用数值模拟方法,对土岩复合地层中深基坑吊脚桩支护结构变形特性进行了研究。研究结果表明,中风化和微风化花岗岩层中常用的“微型钢管桩+锚索”支护结构可以采用“反压岩土+全粘结锚杆”支护结构进行优化;深基坑吊脚桩支护结构施工过程中,地表沉降量和桩身水平位移大多发生在上部土方开挖过程中,因此应在该过程中对基坑支护结构进行变形加密监测;地表最大沉降量出现在距离基坑侧壁约1/10 h(h为基坑开挖深度)位置,桩身水平位移最大值出现在地表以下约1/4 h深度处。

In this paper,taking a deep foundation pit project in Qingdao as an example,the deformation characteristics of deep foundation pit end-suspended pile support structure in soil-rock composite stratum are studied by numerical simulation method.The results show that the support structure of“micro steel pipe pile with anchor cable”commonly used in moderately weathered and slightly weathered granite layers can be optimized by“back pressure rock with soil fully bonded anchor”;During the construction process,most of the surface settlement and horizontal displacement of piles occur in the process of upper earthwork excavation which deformation of foundation pit supporting structure should be monitored;The maximum surface settlement appears at about 1/10 h(h is excavation depth of the foundation pit)of foundation pit,and the maximum horizontal displacement of the pile body appears at about 1/4 h below the surface.