考虑土拱效应的黏性填土排桩桩后土压力研究

研究了考虑土拱效应的黏性填土排桩桩后总土压力的计算方法。以黏性填土的单排支护桩为研究对象，将考虑土拱效应的桩后总土压力分为直接土压力和间接土压力。首先，针对已有土压力计算方法的不足，借鉴并改进了挡土墙的主应力旋转理论，认为主应力旋转后大小会发生改变，通过对土拱单元的应力分析和平衡微分方程的求解，推导出了黏性填土排桩桩后直接土压力的解析式，并将计算结果与前人的解析解和试验数据进行对比，表明改进后的方法与实测数据更加吻合。然后，将改进后的方法应用在黏性土间接土压力的分析中，通过将间接土压力看作是由桩间土体滑裂面上的剪应力沿滑裂面的积分，推导出考虑水平土拱效应的桩后间接土压力和总土压力解析式。最后，探究了总土压力随黏聚力和桩土摩擦角的变化规律，结果表明，土拱效应主要影响桩体H/3深度以下部分，使该部分土压力减小，且越靠近桩底，减小速率越大。该研究可为排桩结构的合理设计提供依据。

Research on earth pressure behind row piles from clayey backfill considering soil arching effect

The calculation method of total earth pressure behind row piles from clayey backfill considering soil arching effect is researched. Against on the single-row retaining piles, the total earth pressure behind row piles which considering the soil arching effect is divided into direct earth pressure and indirect earth pressure. Firstly, in light of the previous researches' weakness, the principal stress rotation theory of retaining wall is used and improved by considering that the value of principal stress is changed after rotating. On this basis, by means of a stress analysis of soil arch element and solving the equilibrium differential equation, an analytical expression for the direct earth pressure is derived. Compared with the analytical solution of predecessors and the measured data, the computed result of the improved method is more consistent with the measured data. Then, the improved method is applied to the indirect earth pressure of the clayey soil, and the analytical expressions for indirect earth pressure and total earth pressure are derived by regarding indirect earth pressure as the integral of the shear stress along the slip surface of the soil between piles. Finally, the change rule of total earth pressure with cohesion and soil-pile friction angle suggested that the soil arching effect mainly affect the lower part of H/3-depth pile body, causing the total earth pressure of this part decrease; and the closer it get to the bottom of the pile, the larger the decrease is. The study can provide a basis for the rational design of row piles.