Abstract The ultimate bearing capacity problem of rectangular surface footing over undrained clay with linearly increased strength is comprehensively analyzed with a numerical upper-bound method. For uniform soil, the present results are generally in accordance with available results and present the best upper-bound prediction when the three-dimensional effect is predominant. The obtained bearing capacity factor for nonhomogeneous soil decreases with the increase of width-length ratio, totally different from that of uniform soil. Accordingly, the shape factor also varies greatly with strength nonhomogeneity. Possible reasons are discussed based on the underlying velocity field. Finally, a strip footing based design equation considering such effect is proposed for the vertical bearing capacity of rectangular surface footings.

中文翻译：

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强度线性增加的粘土矩形面基脚的上限分析

摘要 采用数值上限法，综合分析了强度线性增加的不排水粘土上矩形面基脚的极限承载力问题。对于均质土，目前的结果一般与已有的结果一致，当三维效应占优势时，给出了最好的上界预测。非均质土的承载力系数随宽长比的增大而减小，与均质土的承载力系数完全不同。因此，形状因子也随着强度的非均匀性而变化很大。基于潜在的速度场讨论了可能的原因。最后，针对矩形表面基脚的竖向承载力，提出了考虑这种影响的基于条形基脚的设计方程。