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本文采用有限元法对高层建筑上部结构—桩筏基础—地基共同作用及相互影响进行了研究。研究表明:高层建筑上部结构—桩筏基础—地基共同作用及相互影响时,基础总体沉降和差异沉降随楼层的增加呈非线性变化趋势,上部结构中存在次应力,弯矩和轴力比常规法设计偏大;随楼层的增加,桩体对荷载的分担比在减少,土体分担比在增加;随着上部结构刚度的增加,荷载向角桩、边桩集中;增加筏板厚度,能减少一定的差异沉降和基础平均沉降,从而减少上部结构的次应力,提高地基土的荷载分担比,同时筏板下桩顶反力分布更不均匀,因此需要从筏板受力,以及考虑筏下桩、土的受力来综合确定一个合理的筏板厚度,使设计安全经济;随着地基土变形模量的提高,地基土分担的上部荷载增加,桩顶反力趋向平均,筏板最大弯矩逐渐减小。桩筏基础在均匀布桩条件下呈中间大边缘小的“碟型”分布。差异沉降是由于上部结构次生应力和筏板内力产生的。通过对地基土刚度以及桩长、桩径、桩距等五种桩基刚度的调整,并分析不同刚度对基础差异沉降影响可知:改变桩长的布桩形式并结合地基土刚度调整的中心布桩形式是高层建筑桩筏基础最佳设计方案。
In this paper, the finite element method is used to study the interaction and interaction between the superstructure of superstructure-pile-raft foundation-foundation. The research shows that when the superstructure of superstructure-piled raft foundation-foundation interacts with each other, the total settlement and differential settlement of the foundation show a non-linear trend with the increase of the floor. The substructure stress, moment and axial force are conventional With the increase of the floor, the share ratio of the pile to the load is decreasing and the soil share ratio is increasing. As the stiffness of the superstructure increases, the load is going to the angle pile and the side pile, increasing the thickness of the raft, Reduce the differential subsidence and the average settlement, so as to reduce the secondary stress of the superstructure and improve the load sharing ratio of the foundation soil. At the same time, the reaction force of the pile top under the raft is more uneven, so the force from the raft needs to be considered, Under the force of pile and soil to determine a reasonable thickness of raft to make the design safe and economical. With the increase of deformation modulus of foundation soil, the upper load shared by foundation soil increases, the reaction force of pile top tends to average and the maximum of raft The bending moment decreases gradually. The piled raft foundations distributed in the middle of the big edge under the condition of uniform piling. The differential settlement is due to the secondary stress in the superstructure and the internal force of the raft. By adjusting the stiffness of foundation soil and the stiffness of five kinds of piles, such as pile length, pile diameter and pile spacing, and analyzing the effect of different stiffness on differential settlement, we can see that the distribution of piles with long pile length and the center fabric Pile form is the best design of piled raft foundation of high-rise building.