基于DUNCAN-CHANG模型的刚性桩复合地基沉降变形分析

为研究影响刚性桩复合地基沉降的影响因素,对刚性桩复合地基进行室内压缩试验,基于DUNCAN-CHANG模型利用有限元软件对不同桩长、不同桩径、不同褥垫层厚度和不同桩数(相同置换率)等影响刚性桩复合地基沉降的主要影响因素进行数值模拟.结果表明:随着桩长和桩径的增加,刚性桩复合地基沉降减小,控制桩长比控制桩径对刚性桩复合地基沉降影响效果更加显著,桩侧正负摩阻力的分界点大致在0.4～0.6倍桩长范围内变化,桩土应力比则是在15～17之间变化;当褥垫层厚度较小时,对桩侧摩阻力和桩土之间的受力调节效果不明显,而褥垫层厚度较大时,造成的总体沉降增大,在实际工程中应对褥垫层厚度进行合理设计,建议采用30～50cm.

Analysis about Settlement Deformation of Rigid Pile Composite Foundation Based on DUNCAN-CHANG Model

In order to study the influencing factors that affect the regid column composite foundation,a self-made test device was used to carry out indoor compression tests on regid column composite foundation.Based on the main influencing factors that affect the settlement of the regid column composite foundation with different pile lengths,different pile diameters,different cushion thickness and the different number of pipes(with the same replacement rate)was numerically simulated by the finite element simulation software(Duncan-Chang model used for soil mass selection).The results show that,with the increase of pile length and pile diameter,the settlement of rigid pile composite foundation decreases,and controlling pile length has more significant effect than controlling pile diameter on the settlement of rigid pile composite foundation;and the demarcation point of the positive and negative frictional resistance of the pile is roughly in the range of 0.4～0.6 times the pile length,pile-soil stress ratio varies between 15～17.When the thickness of the cushion layer is relatively small,the effect of force adjustment between pile side friction and the pile soil is not obvious,and when the thickness of the cushion layer is relatively large,the overall settlement will increase.In the actual project,the thickness of the cushion layer should be designed reasonably.Then it is recommended to use 30～50 cm.