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岩土的材料各向异性与K0固结特性的耦合及其本构描述

批准号10872016 学科分类非传染病流行病学 ( H2610 )
项目负责人何耀 负责人职称 依托单位北京航空航天大学
资助金额0.00
万元
项目类别面上项目 研究期限2009 年 01 月 01 日 至
2011 年 12 月 31 日
中文主题词超固结土;材料各向异性;初始固结各向异性;本构模型
英文主题词overconsolidated clay; inherent anisotropy; initially stress-induced anisotropy; constitutive model

摘要

中文摘要 以沉积面和SMP 面的最小夹角α为参数,提出了和夹角α相关的各向异性强度参量Mα表达式。建立的各向异性强度准则,适用于横观各向同性岩土材料,经试验验证表明该强度准则能够合理地反映横观各向同性土的强度特性。在超固结土本构模型中引入了各向异性变换应力张量、相对应力比、状态应力比以及考虑土体材料各向异性的特征状态应力比,建立了各向异性土的UH模型,经模型验证表明该模型能够反映固结初始各向异性和土体材料各向异性对土的应力应变特性的影响。将正常固结土的渐近状态模型推广到K0固结状态,推导出三轴压缩条件下耦合参量的求解公式,建立了K0固结土的渐近状态本构模型。通过试验结果和预测的对比,表明所提模型能合理地预测不同应力状态下K0固结土的应力应变关系。针对砂土在动力荷载作用下所表现出的应力诱导各向异性, 以超固结土UH模型为基础, 采用旋转硬化规则将其扩展为可考虑循环加载效应的砂土动力UH模型。通过进行地基承载力的三维有限元分析、地基固结沉降数值分析,比较了荷载板的竖向压力与位移关系,特征点的应力应变关系,展示了各向异性土的UH 模型的优越性。在FLAC3D中实现了自定义UH本构模型的开发与应用。
英文摘要 An anisotropic peak stress ratio is proposed as a function of the minimum included angle between the spatially mobilized plane (SMP) and the soil depositional plane, and a transformed stress tensor for anisotropic soils has been properly defined by incorporating with the original transformed stress tensor. The capability of the proposed failure criterion is demonstrated through detailed comparisons of the proposed failure criterion and experimental data. The unified hardening (UH) model is extended to account for effects of anisotropic fabric on soil responses under a general stress system. The extended UH model successfully predicts a series of undrained triaxial tests on isotropically and anisotropically consolidated kaolin clay specimens with different overconsolidation ratios. The anisotropic failure criterion and the extended UH model are interpreted in the same constitutive framework. Added basic soil parameters for anisotropic soils can be determined conveniently from the conventional triaxial compression tests on vertical and horizontal specimens.Asymptotic State model for normally consolidated clay is extended to asymptotic state model for K0 consolidated clays. The formulation of partially coupled parameter is deduced under triaxial compression condition. A function of partially coupled parameter associated with Lode's angle is proposed. The UH model for overconsolidated clay is extended to a dynamic UH model considering the stressstrain relationship for both clay and sands by adopting rotational hardening rule. Dynamic UH model is aimed at the stressinduced anisotropy for the both clay and sands under dynamic loading condition. To the test on rigid bearing plate, three-dimensional finite element analysis of foundation bearing capacity is carried out. The stress-strain curves calculated by using the UH model in soil are analyzed. In addition, numerical analysis of consolidation settlement is performed. The changes of pore pressure and settlement are analyzed and compared. It is shown that the UH model is better than the Cam-clay, and it is easy to be applied to the FEM from the comparisons of various calculation results.
结题摘要 以沉积面和SMP 面的最小夹角α为参数,提出了和夹角α相关的各向异性强度参量Mα表达式。建立的各向异性强度准则,适用于横观各向同性岩土材料,经试验验证表明该强度准则能够合理地反映横观各向同性土的强度特性。在超固结土本构模型中引入了各向异性变换应力张量、相对应力比、状态应力比以及考虑土体材料各向异性的特征状态应力比,建立了各向异性土的UH模型,经模型验证表明该模型能够反映固结初始各向异性和土体材料各向异性对土的应力应变特性的影响。将正常固结土的渐近状态模型推广到K0固结状态,推导出三轴压缩条件下耦合参量的求解公式,建立了K0固结土的渐近状态本构模型。通过试验结果和预测的对比,表明所提模型能合理地预测不同应力状态下K0固结土的应力应变关系。针对砂土在动力荷载作用下所表现出的应力诱导各向异性, 以超固结土UH模型为基础, 采用旋转硬化规则将其扩展为可考虑循环加载效应的砂土动力UH模型。通过进行地基承载力的三维有限元分析、地基固结沉降数值分析,比较了荷载板的竖向压力与位移关系,特征点的应力应变关系,展示了各向异性土的UH 模型的优越性。在FLAC3D中实现了自定义UH本构模型的开发与应用。

成果

序号 标题 类型 作者
1 Microscopic study on stress-strain relation of granular materials 期刊 姚仰平|刘斯宏|李铁军|刘敏芝|孙其诚|
2 土的基本力学特性及其弹塑性描述 期刊 姚仰平;侯伟|
3 土的统一硬化模型 期刊 姚仰平;侯伟;罗汀|
4 基于SMP的岩土各向异性强度准则 期刊 罗汀;李萌;孔玉侠;姚仰平|
5 考虑堆石料破碎影响的黏弹塑性本构模型 期刊 姚仰平|黄冠|

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