首页|碎石桩复合地基非等应变非线性固结特性分析

碎石桩复合地基非等应变非线性固结特性分析

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现有碎石桩复合地基固结理论通常基于等应变假设,与工程实际情况有出入.基于分段线性差分法,建立了一种考虑非等应变刺入修正和任意桩土非线性本构关系的碎石桩复合地基非线性固结模型.该模型可以考虑桩土自重、涂抹区、井阻效应和变荷载,可以计算碎石桩向垫层或下卧层的刺入并对等应变假设进行修正,可以分析桩土附加应力沿深度方向的衰减,以及任意的非线性压缩性及渗透性关系.与工程实测数据对比发现,考虑非等应变修正的模型计算值与工程实测值基本吻合.结合算例分析,进一步研究了垫层及下卧层模量、桩土竖向应力衰减和应力路径对碎石桩复合地基土体固结特性的影响,结果表明:碎石桩向垫层或下卧层刺入使复合地基桩土应力比减小、沉降量增大、固结速率减缓;忽略桩土竖向应力衰减虽对固结速率影响不大,但会高估复合地基沉降变形;不同应力路径对碎石桩复合地基固结特性影响显著,简化的土层压缩性关系将对分析结果带来较大误差.
ANALYSIS OF NON-EQUAL STRAIN AND NONLINEAR CONSOLIDATION PROPERTIES OF STONE COLUMN COMPOSITE FOUNDATION
The existing consolidation theory of stone column composite foundation is typically based on the assump-tion of equal strain,which differs from the actual engineering situation.Using the piecewise linear method,we es-tablish a more applicable nonlinear consolidation model for a stone column composite foundation under complex con-ditions.This model considers the penetration of stone columns into the cushion or underlying stratum,correcting for the equal strain assumption.Additionally,the model accounts for the self-weight of stone columns and soil,the smear zone,well resistance effect,time-dependent loading,attenuation of additional stress of stone columns and soil along the depth direction,and any nonlinear compressibility and permeability relationships.In comparison with the project,the calculated results of the model are generally in agreement with the measured values.Combined with the analysis of numerical examples,we further investigate the influence of cushion and underlying stratum modulus,additional stress attenuation,and stress path on the consolidation properties of the stone column composite founda-tion.The results indicate that the penetration of stone columns into the cushion or underlying stratum reduces the pile-soil stress ratio,increases settlement,and slows down the consolidation rate of the composite foundation.Igno-ring the additional stress attenuation of stone columns and soil has little effect on the consolidation rate but will over-estimate the settlement of the composite foundation.Different stress paths have significant effects on the consolida-tion properties of the stone column composite foundation,and a simplified compressibility relationship of the soil layer will introduce large errors into the analysis results.

Composite groundStone columnNon-linearStress pathConsolidation model

周亚东、刘钰婉、郭帅杰、李岩

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天津城建大学 天津市软土特性与工程环境重点实验室,天津 300384,中国

中国铁路设计集团有限公司,天津 300251,中国

碎石桩 复合地基 非线性 应力路径 固结模型

国家自然科学基金项目天津市自然科学基金项目

5160835151608351

2024

工程地质学报
中国科学院地质与地球物理研究所

工程地质学报

CSTPCD北大核心
影响因子:1.215
ISSN:1004-9665
年,卷(期):2024.32(2)
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