层状粘性土及砂土地基中静力压桩连续贯入的数值模拟

NUMERICAL SIMULATION OF THE SUCCESSIVE PENETRATION OF JACKED PILE IN LAYERED COHESIVE SOIL AND SAND

总结分析了软硬交互层状土中静压桩沉桩阻力的变化规律。为了使ABAQUS模拟层状土地基,特别是既有粘性土层又有砂土层的层状地基中静压桩贯入,分段采用不同本构关系模型,即在粘性土层中采用修正剑桥模型,砂土层中采用扩展D-P模型。同时,采用多项措施对层状土地基土体初始应力进行平衡。结合工程实例,模拟计算了不同土层性质差异明显、软土中有硬土夹层的层状土中静压桩连续贯入过程,得出了贯入过程中沉桩阻力随深度变化曲线,反映了通过硬土层时桩周应力和沉桩阻力的突变现象,与实测资料较吻合。研究结果有助于静压桩沉桩可能性分析以及挤土效应分析。

The change of penetration resistance of jacked piles in interactive soft and hard layered soil is analyzed. Different constitutive models have been adopted, including modified cam clay model for cohesive soil and Modified Drucker-Prager model for sand in order to simulate the penetration of jacked piles more reasonably in layered soil particularly in interactive cohesive and sandy layered soil with ABAQUS. Simultaneously, a series of other measures are taken to make the initial stress equilibrium in layered soil. Combining with an engineering case, the process of successive penetration of jacked pile in layered soil with significantly different properties and stiff soil-interlayer in soft soil is simulated and calculated successfully, with the variation cure of pile resistance with depth in penetration process being obtained, which can reflect the abrupt change phenomenon of stress around pile and jacking resistance. The conclusion of numerical analysis is consistent with the field observations. The research results can help probability analysis on penetration of jacked piles and pile squeezing effect.