黏性土填料下考虑土拱效应的非极限主动土压力计算方法

不论挡土墙填料采用砂性土，还是黏性土，其墙背主动土压力与墙体倾角和位移关系存在较大的联系，因而研究黏性土填料下的非极限主动土压力计算理论具有重要意义。通过应力状态分析给出了非极限状态下考虑土拱效应的侧向主动土压力系数，然后采用水平微分层析法给出了倾斜墙下非极限主动土压力解析解。通过与室内模拟试验及已有理论进行对比，验证了该方法的合理性。最后研究了相关参数包括位移比?，墙土摩擦角与内摩擦角之比? /?，墙体倾角?，黏聚力c等对主动土压力分布及其作用点高度的影响。结果表明：土体由静止状态向极限主动土压力状态发展时，土拱效应的影响会越来越大。随着? /?的不断增大，土压力分布曲线非线性强度会不断增强，土压力合力作用点高度呈上升趋势，并且? /?对土压力的影响会随着位移比? 的增大而增大。随着挡土墙墙背倾斜角度? 的不断增大，土拱效应对非极限主动土压力的影响减小。随着土体填料黏聚力的不断增大，上部张拉裂缝高度也会随之增加，且土压力合力作用点越低。给出的考虑土拱效应的非极限主动土压力计算方法对于丰富挡土墙土压力计算理论具有重要意义。

A method to calculate the active earth pressure with considering soil arching effect under the nonlimit state of clayey soil

The active earth pressure depends largely upon the inclining angle and the displacement of a retaining wall backfilled, for either sandy or clayey soil. Thus, it is necessary to address these factors in calculating the active earth pressure of the retaining wall backfilled by the nonlimit-state soil. Based on stress state analysis, the coefficient of lateral earth pressure is determined by considering the soil arching effect and the nonlimit soil state, and a closed form solution is given for the inclined retaining wall using the horizontal element method. The proposed method is validated by comparing the calculated results with model testing results. The key parameters, such as displacement ratio ?, the ratio of soil-wall friction angle and internal friction angle ? /?, inclining angel ?, and cohesion c, are analyzed, which have great influences on the distribution of the active earth pressure and the height of the acting point of the sum of the total earth pressure. It is shown that as the soil state transits from static to actively pushing the wall, the soil arching effect becomes stronger. Also, as ? /? increases, the distribution of the active earth pressure becomes more and more nonlinear and the height of the acting point of total earth pressure increases, while the effect of ? /? on the earth pressure increases as ? increases. In addition, as ? increase, the soil arching effect diminishes. For the cohesive soil, the cohesion has influence on the active earth pressure, and the height of the acting point of total earth pressure decreases as the cohesion increases. The proposed method may help improve the calculation of active earth pressure behind the retaining wall.