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大直径扩底灌注桩的沉降以桩端土层的竖向压缩变形为主,因此端承土层特性对大直径扩底桩的竖向承载性状有较大影响。利用有限差分程序建立三维非线性有限差分数值模型,研究了持力层性质对大直径扩底桩竖向承载性状的影响。结果表明,大直径扩底桩承载力随持力层厚度的增加而增大,且在持力层厚度较小时持力层厚度的变化对承载力和桩端阻力影响显著。桩侧土层模量与持力层模量比为0.2时,桩端入持力层深度的变化在持力层厚度较小时对大直径扩底桩的极限承载力影响较大。相同持力层厚度下,桩侧土层模量的变化对大直径扩底桩承载力的影响较大,模量越大承载力越高;下卧层模量的变化对大直径扩底桩承载力的影响较大。
The settlement of large-diameter expanded bottom piles is mainly caused by vertical compression deformation of the pile-end soil. Therefore, the characteristics of end bearing soil layer have a great influence on the vertical bearing behavior of large-diameter piles. The finite difference numerical program was used to establish the three-dimensional nonlinear finite difference numerical model, and the effect of bearing layer properties on the vertical bearing behavior of large diameter pile was studied. The results show that the bearing capacity of large diameter piles increases with the increase of bearing layer thickness, and the change of bearing layer thickness has a significant effect on bearing capacity and pile end resistance when the bearing layer thickness is small. When the ratio of soil layer modulus and holding layer modulus is 0.2, the change of depth of pile end holding force has a great influence on the ultimate bearing capacity of large diameter pile when the thickness of bearing layer is small. Under the same bearing layer thickness, the change of soil layer modulus on pile side has a great influence on the bearing capacity of large-diameter expanded pile, the higher the modulus is, the higher the bearing capacity is. The impact of bearing capacity is bigger.