层状地基中考虑桩端应力扩散的单桩沉降计算

Calculation method for settlement of single pile considering stress dispersion of pile end soil

针对现行单桩沉降计算方法没有考虑桩端应力扩散效应的问题,基于虚土桩模型,提出一种考虑桩端应力扩散效应时层状地基中的单桩沉降计算方法.在土层处于弹性状态下,桩侧土采用双折线模型,桩端土采用虚土桩模型并考虑应力扩散效应,利用荷载传递法,推导出层状地基中考虑桩端应力扩散效应时的单桩沉降计算公式.进一步讨论了该方法中弹性极限位移、弹性抗剪切刚度系数、桩端土厚度和应力扩散角等参数对单桩沉降的影响.结合工程实测数据,对比了该方法计算的荷载-沉降曲线、由规范方法得到的荷载-沉降曲线和实测曲线,结果表明:考虑桩端应力扩散效应时单桩沉降计算方法计算得到的桩顶沉降值与实测值较为吻合,实际工程应用优于规范法.

For the current methods can not consider the stress dispersion of pile end soil,a calculation method was presented for the settlement calculation of single pile embedded in layered soils by assuming pile end soil to be virtual soil pile which took into account the stress dispersion of pile end soil.In the elastic state,by using bilinear load transfer model to simulate the surrounding soil and using the virtual soil pile model which took into account the stress dispersion to simulate the pile end soil,a set of analytical equations for the settlement of single pile embedded in layered soils considering stress dispersion of pile end soil were obtained by virtue of the load transfer method.The effects of elastic limit displacement,elastic shear stiffness coefficient,length of virtual soil pile and cone angle on the settlement of single pile were analyzed.Comparisons of the calculation results of this method with those of the normative method and the measured data showed that the pile top settlement calculated by this presented method was approximate to the measured value,and also superior to the normative method.