桩筏基础桩土荷载分担比研究

Study on Pile-soil Load-sharing Ratio of Pile-raft Foundation

为解决在传统设计方法中忽略筏基下土体承载力的问题,利用有限元分析软件ABAQUS建立带筏板的双桩模型,深入分析改变距径比、长径比、端间土模量比、桩间土弹性模量、筏板厚度、垫层厚度、垫层弹性模量对桩土荷载分担比的影响。计算结果表明:当距径比增大时,桩体荷载分担比逐渐减小;当长径比增加时,桩体荷载分担比随之增大;端间土模量比的改变对桩体荷载分担比影响很小;随着桩间土弹性模量的增大,桩体荷载分担比有明显变小趋势;筏板厚度对桩体荷载分担比影响不大;随垫层厚度增加桩体荷载分担比逐渐减小,且减小幅度逐渐减小最终趋于平缓;垫层弹性模量越大桩体荷载分担比越大。综合考虑对桩土荷载分担比影响较大的因素,总结归纳出桩体荷载分担比计算公式,其计算结果较为准确。

In order to solve the problem of neglecting the bearing capacity of the soil under raft foundation in traditional design method,a double pile model with raft slab was established by using finite element analysis software ABAQUS,and further analysis was carried out.The variation of pile-soil load-sharing ratio was discussed when the distancediameter ratio,length-diameter ratio,modulus ratio of end-to-side soil,elastic modulus of soil between piles,raft thickness,cushion thickness and cushion elastic modulus were changed.The calculation results show that the loadsharing ratio of pile body gradually decreases with the increase of distance-diameter ratio.When the length-diameter ratio increases,the load-sharing ratio of the pile body increases accordingly.The change of modulus ratio of end-to-side soil has little effect on load-sharing ratio of pile body.With the increase of the elastic modulus of the soil between piles,the load-sharing ratio of pile body tends to decrease obviously.The raft thickness has little effect on the load-sharing ratio of pile to soil.With the increase of cushion thickness,the load-sharing ratio of piles gradually decreases,and the reduction amplitude gradually decreases and eventually flattens.The greater the cushion elastic modulus,the greater the load-sharing ratio of the pile body.The factors that have a greater impact on pile-soil load-sharing ratio are comprehensively considered.The calculation formula of the pile-soil load-sharing ratio is summarized,whose calculation result is more accurate.