肋式支护结构支护性能分析与位移预测

肋式支护结构是由钢板桩和与钢板桩刚性连接的肋板组成的新型基坑支护结构，已有工程案例证明其支护性能较好，然而其支护机理尚缺乏深入研究及试验佐证。运用有限元数值分析方法研究了肋式支护结构在基坑开挖过程中的变形和受力特征以及基坑的稳定性，与实测数值进行了对比；分析计算了不同肋板宽度和间距对结构水平位移和稳定性的影响规律，提出了肋式支护结构最大水平位移预测公式，可用来预估实际支护结构的可能位移值。研究结果表明：对于同一个实例工程，相较于传统钢板桩结构，采用肋式支护结构时结构位移和内力显著减小，在肋板宽度为1.60 m、肋板间距为0.80 m时板桩最大水平位移可减小71.56%，板桩弯矩分布得以改变，桩身弯矩大幅减小，基坑稳定性更高；增设肋板不仅使结构抗弯刚度大幅提高，而且能够产生较大的锚固拉力来抵抗前排钢板桩所受的主动土压力。

Analysis of support performance and deformation prediction of ribbed supporting structure

Ribbed supporting structure is a new type of foundation pit supporting structure, which is composed of steel sheet piles and rib plates that rigidly connected with the piles. The existing engineering cases have proved that the supporting performance of the structure is satisfactory. However, the supporting mechanism of this structure is yet to be further investigated and proved by experiments. In the process of foundation pit excavation, the deformation and mechanical characteristics of the ribbed support structure and the stability of foundation pit are studied by finite element method, and the calculated results are compared with the measured values. Moreover, the influence of rib-width and rib-spacing on the horizontal displacement and stability of the structure is analyzed. According to the analysis, the maximum horizontal displacement prediction formula is proposed, which can predict the actual possible displacement of the support structure. The results showed that the displacement and internal force of the ribbed support structure are much smaller than those of the conventional support structure of steel sheet piles for the same project, for example, the maximum horizontal displacement of the sheet piles is decreased by 71.56% when the rib-width is 1.60 m and the rib-spacing is 0.80 m. In this case, the bending moment distribution of sheet piles is relocated, the bending moment of the sheet pile is greatly reduced, so the stability of the foundation pit is improved. Rib plates can not only greatly improve the bending stiffness of the structure, but also can produce a larger anchor tension for the structure to resist the soil pressure on the front row of steel sheet piles.