毛竹复合土钉墙工作性状的数值分析研究

以某软土基坑采用毛竹复合土钉墙支护的工程实例为背景,利用有限元软件PLAXIS建立某设计剖面的平面应变有限元模型。为提高数值分析定量计算分析的精度,采用了能反映土体小变形和加卸载变形等特点的小应变刚度模型。通过对土钉墙面层及毛竹排桩的水平位移、坡顶沉降、毛竹土钉的轴力以及毛竹排桩的剪力和弯矩分布规律的分析,对堤坝形毛竹复合土钉墙的工作性状获得了较全面的认识,并探索了其可能的失稳破坏形式。采用该程序自带的强度折减有限元法计算了各开挖工况下支护体系的稳定安全系数,表明毛竹复合土钉墙在施工期间和施工后均具有较高的稳定性,具备可靠的支护能力。

Numerical Analysis on Working Performance of Composite Moso Bamboo Soil Nailing Wall

Based on a practical soft soil foundation pit which used the composite moso bamboo soil nailing wall as its retaining structure, the plane-strain finite element model of a design profile of the foundation pit engineering was established by using the finite element software PLAXIS. In order to improve the quantitative computation accuracy of numerical analysis, the small-strain stiffness model, which is able to describe the soils’ small deformation behavior and loading or unloading deformation characteristics, is employed. The working performance of the composite moso bamboo soil nailing wall is comprehensively understood by analyzing the distribution laws of the horizontal displacements of the surface course and the moso bamboo piles, the vertical displacements of the ground surface, the axial force of the moso bamboo soil nails as well as the shear force and moment of the moso piles. In addition, the possible failure form of this retaining structure is revealed. Using the strength reduction finite element method embedded in the PLAXIS, the safety factors of the earth-retaining system at each excavation stage were computed. It is shown that the composite moso bamboo soil nailing wall has higher stability and reliable earth-retaining capability during the construction process and after the construction.