刚性挡土墙平移模式的土拱形状与主动土压力分析

Analysis of soil arch and active earth pressure on translating rigid retaining walls

与假定土拱形状与水平层分析相结合的土压力计算方法不同,本文不事先假设土拱形状,考虑条间剪切应力的影响,通过对滑动土体中二维微分单元的受力分析建立平衡微分方程,得到了滑动土体中任一点的应力解。同时求得作用在挡土墙上的土压力,并进一步推导出土拱曲线的解析表达式,讨论了内、外摩擦角等因素对土压力与土拱形状的影响,且与现有理论和试验结果进行了比较分析,在此基础上提出一个实用的土压力计算公式。计算结果表明:土压力计算公式得到的土压力分布与试验结果吻合较好,且当墙高增加时吻合程度更高。当外摩擦角较小时,土拱曲线表达式得到的土拱与圆弧拱较接近,随着外摩擦角的增大土拱越来越陡,但整体位于抛物线拱之下。该研究所提出的实用计算公式只与?/?有关,方便工程上应用。

Compared with the existing method combining soil arch shape and horizontal layer analysis,this study has no assumption of soil arch shape and shear stress is considered.The stress solution of any point in the sliding soil is obtained by solving equilibrium differential equations of the two-dimensional differential element,and the active earth pressure imposed on the rigid wall is further derived.Subsequently,based on the stress state of any point in the sliding soil,the analytic expression of the arch shape is established.Furthermore,the effects of internal friction angle,soil-wall friction angle on earth pressure and soil arching shape are discussed.Finally,the obtained results are compared with the results derived from existing theory and experimental results,and the conversion formula between the proposed active earth pressure coefficient and Coulomb theory is obtained.The results indicate that the proposed distribution of earth pressure is in good agreement with the experimental results,especially in the case of high wall.When the soil-wall friction angle is small,the calculated soil arch is similar to the arc,and the soil arch becomes steeper in terms of the increase of soil-wall friction angle,which is always under the parabolic arch.The practical formula is only related toδ/φ,which is convenient to use in engineering.