考虑荷载埋深与K_0变化的地基临界荷载

Critical load of ground considering load embedded depth and variation of K_0

传统的地基临界荷载计算方法将荷载埋深土体等同于超载,没有考虑荷载埋深对地基附加应力分布的影响,也没有反映静止土压力系数变化对地基自重应力的影响。基于分布荷载作用于地基内部的附加应力计算公式,同时考虑静止土压力系数随地基土内摩擦角变化条件下,计算分析了地基的临界荷载。计算结果表明,假设静止土压力系数恒等于1高估了地基的临界荷载,静止土压力系数的变化对地基临界荷载的影响不可忽略。考虑荷载埋深的影响则使地基附加应力显著降低,当荷载埋深为1倍荷载分布宽度时,竖向附加应力相对于无埋深条件最大降低了29.3%,临界荷载也提高了38.4%～44.6%。考虑荷载埋深对地基附加应力的影响后,埋深对地基临界荷载的影响不再是线性的,当埋深较大时,埋深的影响随埋深的增加逐渐减小。

In traditional methods for the critical load,the soil above load working plane is treated as surcharge,which does not consider influence of embedded depth on subsidiary stress distribution or the variation of coefficient of earth pressure at rest on self-weight stress.Based on the subsidiary stress formula of embedded distributed load and considering that the coefficient of earth pressure at rest varies with internal friction angle of ground material,the critical load of ground is investigated.The calculated results indicate that the critical load is overestimated if the coefficient of earth pressure at rest equals 1,and that the variation of lateral earth pressure can not be neglected.The subsidiary stress in ground significantly reduces and the critical load increases by a large margin after the influence of load embedded depth is considered.The vertical subsidiary stress is reduced by 29.3% at most and the critical load increases by 38.4%～44.6% when the load embedded depth equals the load distributed width.The effect of load embedded depth on the critical load is nonlinear,and the influence of load embedded depth decreases with the increase of depth.