北京某基坑阳角部位土钉支护的冗余度设计研究

Study on Redundancy Design of Soil Nailing Retaining in the External Angle of a Foundation Pit in Beijing

以北京某基坑阳角土钉支护工程为背景,采用Midas/GTS软件建立了该基坑阳角开挖模型,以土钉轴力和土体变形为标准,计算支护体系的冗余度,并分析了腰梁加固和阳角参数对基坑支护体系冗余度影响特征。结果表明:①与无腰梁体系相比,土钉一腰梁共同工作的整体能够很好控制阳角危险位置处的位移,同时增加支护体系的传力路径,提高支护体系冗余度。腰梁的设置提高了支护体系变形冗余度。②土钉一腰梁支护体系能够降低阳角附近土钉轴力,保护危险构件,提高支护体系承载力冗余度。③基坑阳角凸出长度增大,支护体系冗余度降低;基坑阳角角度减小,支护体系冗余度相应降低。

Based on the Soil Nailing Retaining project in the external angle of a foundation pit in Beijing. By using Midas/GTS software, theexcavation model of the foundation pit is established, the redundancy of the support system is calculated by taking soil nail axial force and soil deformation as the standard, and the influence of reinforcement of waist beam and parameters of the external angle on redundancy of the foundation pit support system are analyzed. The results show： ①Compared with the no-waist beam system,displacements of the negative position in the external angle can be controlled positively by the soil nail-waist beam system. Also, the force transmission paths are added and the redundancy is improved. ②By using the soil nail-waist beam system, the axial force of nail near the external angle can be reduced, the dangerous components can be protected and the redundancy of bearing capacity can be also improved. ③The redundancy of supporting system is reduced with the external angle＇s protruding length increase and the size of the external angle reduce.