圆形基础的临界荷载和形状系数

基于圆形荷载下地基中任意一点应力分量的弹性力学公式和Mohr-Coulomb极限平衡理论计算出最大塑性区深度达到1/4基础直径对应的临界荷载.通过圆形与条形基础临界荷载的比较,进一步得到了圆形基础界限荷载的承载力系数和形状系数.将这些形状系数与已有的各种极限荷载形状系数进行比较,发现与黏聚力和埋深有关的形状系数略小于极限荷载中的数值,与基础宽度有关的形状系数与极限荷载中的数值差距较大,建议按偏小的Meyerhof形状系数取值.算例表明:圆形基础临界荷载相对于极限承载力的安全系数与条形基础界限承载力相对于极限承载力的安全系数大致是匹配的.

Critical Load and Shape Factors of Circular Foundations

According to Mohr Coulumb Criterion and the elastic theory for circular distribution pressure,the critical bearing capacity can be determined,which is the pressure when the maximums depth in plastic zone is upto one fourth of the diameter.Based on a comparison with strip foundation,the critical bearing capacity factors and shape factors are presented.The shape factors of the critical bearing capacity for circular foundation are compared with those of several ultimate bearing capacity.Similarity is found for the shape factors in relation with cohesion and embedded depth of foundation,but inconsistency is found for the shape factor in relation with width of foundation,which is advised to adopt Meyerhof’s shape factor for safety.The safety factor of the ultimate capacity divided by the critical one for circular foundation is consistent with that for strip foundation.