复合双层地基的极限承载力计算

CALCULATION FOR ULTIMATE BEARING CAPACITY OF COMPOSITE GROUND WITH DOUBLE SOIL STRATA

根据极限平衡理论 ,假定了复合双层地基滑移线形状 ,并由此推导了其极限承载力计算方法。通过和太沙基承载力公式进行的对比计算发现 :当内摩擦角较小时 ,两种方法计算结果相近 ,但随着内摩擦角的增大 ,作为半经验公式的太沙基理论出现了一定的偏差 ;粘聚力、容重对极限承载力的影响远小于内摩擦角的影响。文中最后分别用复合双层地基和双层地基极限承载力公式进行了实例计算 ,结果显示忽略下卧层土体的内摩擦角会使得计算结果过于保守。

Based on the limit equilibrium theory,that the sliding line shape of composite ground with double soil strata has been assumed and the calculating method for its ultimate bearing capacity can be derived simultaneously.Through compared the derived calculating method with the Terzaghi's formula method for ultimate bearing capacity,it will be found that the caculating results of both two methods are in good agreement when internal friction angle is small,but the errors in Terzaghi's formula will become obvious with the growing of internal friction angle.The influence of cohesion and unit weight of soil on ultimate bearing capacity are much smaller than that of internal friction angle.Finally,a comparison of the calculating ultimate bearing capacity between the double soil strata ground and the composite ground with double soil strata,using respective formula for practical examples,is carried out,it is shown that if neglecting internal friction angle of soil substratum,that the calculating results will be in the more conservative side.