黏性土坡上裙板式条形基础的极限承载力

由于斜坡的存在,坡上基础的极限承载力相比平地时有所下降,设置裙板可提高其承载力。目前关于坡上裙板基础承载力的研究尚不充分。以黏性土坡上裙板式条形基础为研究对象,采用数值模拟的方法研究其在不排水条件下的极限承载力。首先通过与承载力理论解的比较验证了数值计算的可靠性,然后通过大量算例分析了影响承载力的因素。结果表明:坡角对承载力有明显的不利影响,设置裙板可使地基承载力明显提高,且承载力增幅随裙板相对高度增大而增大。当坡角较大时,基础与坡顶的相对距离对地基破坏模式和承载力有显著影响;随着基础与坡顶相对距离的增加,地基土在荷载作用下的运动趋势受斜坡的影响逐渐减小,因此裙板基础的承载力逐渐增大。但当不排水强度较低时,裙板对承载力的贡献较小。根据数值计算得到的承载力影响因素,并结合前人的理论研究,推导坡上裙板基础不排水极限承载力的计算公式。公式通过引入折减系数来考虑斜坡对基础承载力的影响,通过引入深度系数来考虑裙板对承载力的贡献。将公式计算结果与数值解进行对比验证了公式计算的准确性。

Ultimate bearing capacity computation of skirted strip footing on the cohesive soil slope

Due to the existence of slope,the ultimate bearing capacity of footing on slope is lower than that on flat ground,and the bearing capacity can be increased by adding skirts below footing.At present,the research on the bearing capacity of skirted footing on slope is still in deficiency.Under this background,this study focuses on the skirted strip footing located on cohesive slope,and the numerical simulation method is applied to determine the ultimate bearing capacity under undrained condition.Firstly,the results of numerical computation are compared with theoretical solution of bearing capacity to verify the reliability of numerical computation.And then the factors affecting the bearing capacity are analyzed through a large number of numerical models.The results indicate that the slope angle has a negative effect on the bearing capacity,and the footing bearing capacity can be increased effectively by setting skirt,and the bearing capacity increases with the relative height of skirt.When the slope angle is large,the relative distance between footing edge and slope crest has an appreciable effect on failure mode and bearing capacity of the footing.With the increase of the relative distance between footing edge and slope crest,the effect of slope on the movement tendency of soil is gradually reduced,so the bearing capacity of skirted footing increases gradually.Nevertheless,the influence of skirts on the bearing capacity is not significant when the undrained strength of soil is not high.According to the influence factors obtained from numerical computation and the previous relevant theoretical research,the equation of ultimate bearing capacity of skirted footing on cohesive slope without drainage is derived.In the equation,the reduction coefficient is introduced to consider the negative effect of slope,and the depth coefficient is introduced to define the positive effect of skirt.The accuracy of derivation is verified by comparing the equation calculation with the numerical computation.