基于相关规范中双排桩、重力式围护结构抗倾覆安全系数计算方法对比分析和双排桩支护体系倾覆力、抗倾覆力组成分析,提出了一种考虑前排桩抗压、后排桩抗拔力偶和地下水浮力对双排桩抗倾覆安全系数影响的改进计算方法。工程案例验算表明同条件下,改进后的双排桩抗倾覆安全系数计算值相比于规范中公式计算值可提高20%~55%。利用自主研发的中勘之星双排桩计算软件进行抗倾覆安全系数影响因素分析,结果表明随着支护桩嵌固深度变大,双排桩抗倾覆安全系数先减小后增大,前排桩抗压与后排桩抗拔力偶对转动点的力矩对抗倾覆安全系数起的作用越来越小;随着双排桩排距增大,抗倾覆安全系数呈近似线性增加,前排桩抗压与后排桩抗拔力偶对转动点的力矩对抗倾覆安全系数起的作用越来越大。改进的双排桩抗倾覆安全系数计算方法可为相关工程双排桩抗倾覆安全系数计算提供参考。

An improved method for calculating the anti-overturning safety factor of supporting structure with double-row piles is presented. The method takes into consideration the influence of compressive resistance of first-row pile and uplift resistance of back-row pile coupled with groundwater buoyance. The calculation methods for anti-overtur-ning safety factor of double-row piles and gravity retaining structure in different specifications in China are compared. The compositions of overturning force and overturning resistance are also analyzed. The calculation results of engineering cases show that compared with the results calculated by specification formulas, the anti-overturning safety factor calculated by the present method could improve by 20%-55%. The influence factors of anti-overturning safety factor are analyzed by a self-developed software, and the results indicate that with the increase of built-in depth of supporting pile, the anti-overturning safety factor of double-row pile decreased firstly but then increased. The impacts of the torque generated by the coupling between compressive resistance of first-row pile and uplift resistance of back-row pile on the safety factor weakened. Moreover, with the increase of array pitch, the anti-overturning safety factor increased approximately linearly, and impacts of the torque generated by the coupling between compressive resistance of first-row pile and uplift resistance of back-row pile on the safety factor strengthened.