考虑不完全土拱效应的浅层地基竖向应力计算

浅层岩溶土洞塌陷和浅埋隧道施工等时常会引发浅层地基出现局部沉陷，导致地基可能承受不完全土拱效应作用。如何定量分析不完全土拱效应对浅层地基竖向应力的影响尤为重要。统计了国内外浅层活动门试验，将浅层地基滑移面概化为塔形，同时考虑了浅层地基不同深度处土层差异沉降及主应力偏转过程。通过建立主应力偏转角与活动门相对位移之间的数量关系，量化了浅层地基不同深度对应的不完全土拱效应发挥程度，优化了考虑不完全土拱效应的浅层地基竖向应力计算方法。分析了主要参数对不完全土拱效应的影响，结果表明，随着浅层活动门高宽比及相对位移的增大，应力转移量增加，土体有效内摩擦角及滑移面倾角则相反。可为局部沉降作用下的浅层地基竖向应力计算提供理论指导。

Vertical stress calculation of shallow foundations based on partially developed soil arching effect

Karst collapse and shallow tunnel construction frequently cause partially ground settlement of shallow foundations, resulting in partially developed soil arching effect. Development of approaches to quantitatively analyze the influence of partially developed arching on vertical stresses is of much importance. Through shallow trapdoor tests, it is summarized that the shape of slip plane of shallow trapdoor may be tower-shape under plane strain conditions. Analytical solutions to coefficients of lateral and vertical stresses for any depth of the shallow foundation under the action of partially developed soil arching effect are deduced and proved, which are based on the principal stress rotation and the differential settlement of soil layers. The influence of main parameters about partially developed soil arching effect is investigated. The results reveal that the larger depth-width ratio and the displacement-width ratio of trapdoor are needed to fully develop the arch. In addition, the vertical stress of fill increases with the increase in the effective angle of internal friction and angle of slip plane. The corresponding results can provide theoretical guidance for the calculation of vertical stress of shallow subsoil subject to local settlements.