土钉墙+水泥土桩墙联合支护结构的力学特性分析

Analysis of mechanical properties of a novel support structure with soil nailing wall combined with cemented soil pile/wall for deep excavation

为充分发挥水泥土桩墙的高强度特性,提出了一种土钉墙+水泥土桩墙的基坑联合支护结构,并介绍了其设计理念。基于有限元数值模型,结合南昌地区典型地质条件,系统地研究了联合支护结构对渗流场、土体水平位移、土钉轴力、水泥土桩墙桩身应力、基坑破坏模式的影响,以及坑底加固、水泥土桩墙距离对基坑支护性能的影响,并与传统土钉墙和复合土钉墙支护结构进行了对比分析。结果表明:在保证墙体安全的条件下,联合支护结构的受力机制更合理,开挖面处土体水平位移、桩身轴向及切向应力均小于传统的土钉墙和复合土钉墙;基坑破坏模式表现为重力式挡土墙破坏模式,对坑底进行加固处理可进一步显著改善其支护性能。

In order to fully utilize the high strength of the cemented soil pile/wall,a retaining structure with soil nailing wall combined with cemented soil pile/wall for deep excavation is proposed and its design philosophy is discussed in this paper.Based on finite element numerical simulation combined with the typical geological condition of Nanchang area,the distribution characteristics of seepage flow,horizontal soil displacement,axial force of soil nail,stress of cement-soil pile wall and the failure mode as well as the influence of bottom reinforcement and cement-soil pile wall distance of the novel structure on the support performance are systematically studied.Meanwhile,comparative analysis with the traditional soil nailing wall structure and the composite soil nailing wall structure are conducted.The results show that:Under the condition of ensuring the safety of the wall,the support mechanism of the novel structure is more reasonable due to the horizontal displacement of the soil at the excavation face and the axial and tangential stresses of cement-soil pile wall much smaller than that under the traditional soil nailing wall structure and the composite soil nailing wall structure;the failure mode of the foundation pit is similar with that under the gravity retaining wall support method,and reinforcement of the pit bottom can significantly improve its support performance.