共查询到20条相似文献,搜索用时 109 毫秒
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超固结土的一维固结理论及其试验研究 总被引:1,自引:0,他引:1
基于超固结饱和土固结理论,针对变荷载、自重应力分布等条件下提出3了相应的一维超固结土问题的控制方程,总结出六个超固结土的一维线性固结计算参数.并采用半解析法编制了求解该问题的Fortran计算程序.利用GDS高级固结仪对萧山黏土进行超固结土的一维固结渗透联合试验以及一维固结压缩试验,将测定的一维超固结土计算参数引入理论程序中,分别对比了位移、平均固结度、底部孔压这三者随时间变化的理论和试验曲线.结果表明:超固结土的一维线性固结理论比正常固结土的一维线性固结理论更接近试验结果,验证了超固结土的固结理论,表明了考虑土体应力历史对固结计算的重要性. 相似文献
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Zhiyong Ai Chao Wu 《力学学报》2009,41(5):801
对多层地基的平面应变固结问题进行了研究,并同时考虑了土体的渗透各向异性和孔隙
流体的可压缩性. 从平面应变Biot固结的控制方程出发,对时间t, 坐标z和x进行
Laplace和Fourier变换,建立了地基表面(z=0)和任意深度z处的基本量
在Laplace-Fourier变换域内的传递矩阵关系. 利用传递矩阵
法,结合土层连续条件和边界条件,并应用Laplace-Fourier逆变换技术,推导出渗透各向
异性可压缩多层地基平面应变固结的理论解. 基于该解,编制了计算程序,并进行了
数值计算. 讨论了土体的渗透各向异性、孔隙流体的可压缩性以及地基的分层特性对地基固
结的影响,分析结果表明:土体的渗透各向异性、孔隙流体的可压缩性,以及地基的分层特
性对地基的固结行为有着重要的影响. 相似文献
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对多层地基的平面应变固结问题进行了研究,并同时考虑了土体的渗透各向异性和孔隙流体的可压缩性.从平而应变Biot固结的控制方程出发,对时间t,坐标z和x进行Laplace和Fourier变换,建立了地基表面(z=O)和任意深度z处的基本量在Laplauce-Fourier变换域内的传递矩阵关系.利用传递矩阵法,结合土层连续条件和边界条件,并应用Laplace-Fourier逆变换技术,推导出渗透各向异性可压缩多层地基平面应变固结的理论解.基于该解,编制了计算程序,并进行了数值计算.讨论了土体的渗透各向异性、孔隙流体的可压缩性以及地基的分层特性对地基同结的影响,分析结果表明:土体的渗透各向异性、孔隙流体的可压缩性,以及地基的分层特性对地基的固结行为有着重要的影响. 相似文献
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解析法求解成层渗透各向异性地基Biot固结轴对称问题 总被引:2,自引:0,他引:2
采用解析法研究成层渗透各向异性地基,该法从渗透各向异性Biot固结轴对称问题的基本方程(静力平衡方程,物理方程及渗透连续方程)出发,利用Laplace~Hankel变换及有关矩阵理论等,得到Biot固结基本量不同深度之间的传递矩阵。利用传递矩阵,边界条件以及Laplace~Hankal逆变换技术可求解多层渗透各向异性地基体系,采用更为有效的F.Durbin的方法实现Laplace逆变换。编制了计算 相似文献
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针对传统一维Terzaghi固结理论的局限性,本文引入了考虑时间效应的UH (unified hardening)本构模型,将Hansbo渗流模型耦合到UH本构模型固结方程中,建立了几种典型循环荷载作用下基于UH模型和考虑Hansbo渗流模型的固结方程。采用FlexPDE软件进行了数值分析,将计算结果与已有文献结果对比,验证了该算法的可靠性。在此基础上,研究了饱和黏土在几种典型循环荷载作用下的渗流固结特性,分析了各模型参数对饱和黏土固结特性的影响。结果表明:在循环荷载作用下,地基的平均固结度、沉降量等始终处于循环状态;Hansbo渗流模型参数对平均固结度的影响相对于Darcy渗流参数影响程度较大,其中UH模型中次固结系数对固结过程影响程度较大。另外,Hansbo渗流参数及土的回弹指数和渗透指数等对固结过程的影响主要体现在中期,固结过程后期将处于稳定循环状态。 相似文献
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The parametric variational principle for elastoplasticity 总被引:4,自引:0,他引:4
A parametric variational principle, the parametric minimum potential energy principle (abbreviated to PMPEP), is presented
for the elastoplastic problems. The principle proposed is free from the restraint of Drucker's postulate and consequently
suitable for solving the nonassociated plastic flow problems in rock, soil, concrete and other geomaterials. 相似文献
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This paper presents the parametric variational principle for Perzyna model which isone of the main constitutive relations of viscoplasticity.The principle,by which the potentialenergy function is minimized under a constrained condition transformed by the constitutiverelations of viscoplasticity,is free from the bound of Drucker’s postulate of plastic flow andconsequently suitable for solving the nonassociated plastic flow problems.Furthermore,the paper has proven the presented principle and discussed the creep problem. 相似文献
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岩土类介质在承受荷载时,不仅产生弹塑性变形,还伴随着渗流和固结,是一个关于时间的动态过程。本文建立起处理该问题的参变量变分原理以及相应的有限元方法,这样将原问题化为求解带约束条件(本构状态方程)的二次规划问题.文中讨论了单元的选取形式及具体的实施过程,还给出了一个实例. 相似文献
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The parametric minimum complementary energy variational principle is given in this paper. To the problems of nonassociative
flow rule in the theory of plasticity, the Drucker postulation can no longer be applied and the classical variational principles
fail, the parametric variation principles can play the role instead. The parametric variational principle can be used for
the finite element solution with sequential quadratic programming method to soil mechanics problems. 相似文献
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Q. M. Li 《Archive of Applied Mechanics (Ingenieur Archiv)》1999,69(6):379-392
Summary A dissipative flow model is presented to describe dissipative deformation processes in a macroscopic solid continuum. Dissipative
process may consist of material plasticity, material damage and other intrinsic mechanical phenomena represented by internal
variables. The concept of a dissipative surface is introduced in the paper to distinguish between conservative and dissipative
processes. Conventional plastic yielding and damage initiation are expressed by a unique condition which may else include
other possible intrinsic mechanical dissipations. The proposed model is based on the principles of irreversible thermodynamics
and the minimum free energy theorem. A modified material stability postulate, modified Drucker's postulate, in thermodynamic
stress space is also used to obtain the same results.
Received 1 July 1998; accepted for publication 13 January 1999 相似文献
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In this paper it is shown that the thermodynamic reference stress soKL which is associated with the state of plastic strain must always be within or on the yield surface. A restriction is therefore imposed on the functions representing the yield surface, the free energy, and strain hardening. An example is given in which soKL ultimately moves outside the yield surface provided that these functions are not selected properly. The paper also includes a discussion of Drucker's postulate of stability in the small and whether or not this postulate is essential for the theory of plasticity. 相似文献
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Francesco Solombrino 《Archive for Rational Mechanics and Analysis》2014,212(1):283-330
Inspired by some recent developments in the theory of small-strain heterogeneous elastoplasticity, we both revisit and generalize the formulation of the quasistatic evolutionary problem in perfect plasticity given by Francfort and Giacomini (Commun Pure Appl Math, 65:1185–1241, 2012). We show that their definition of the plastic dissipation measure is equivalent to an abstract one, where it is defined as the supremum of the dualities between the deviatoric parts of admissible stress fields and the plastic strains. By means of this abstract definition, a viscoplastic approximation and variational techniques from the theory of rate-independent processes give the existence of an evolution satisfying an energy-dissipation balance and consequently Hill’s maximum plastic work principle for an abstract and very large class of yield conditions. 相似文献
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基于经典弹塑性理论中多数屈服准则具有凸锥数学结构的事实,将在大规模计算中更具潜力的锥规划法引入弹塑性分析。考虑到弹塑性流动理论有关联与非关联之分,本文提出利用锥型互补法求解弹塑性问题。具体以Drucker-Prager弹塑性模型为例,首先利用最大塑性功耗散原理和圆锥对偶理论等工具,建立了弹塑性本构方程的等价二阶锥互补模型;然后,基于参变量变分原理和有限元技术,建立了弹塑性增量分析的二阶锥线性互补模型;最后,利用一类半光滑Newton算法求解。数值算例表明了本文方法的有效性。 相似文献
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Gianni Dal Maso Antonio DeSimone Maria Giovanna Mora 《Archive for Rational Mechanics and Analysis》2006,180(2):237-291
The problem of quasistatic evolution in small strain associative elastoplasticity is studied in the framework of the variational
theory for rate-independent processes. Existence of solutions is proved through the use of incremental variational problems
in spaces of functions with bounded deformation. This approach provides a new approximation result for the solutions of the
quasistatic evolution problem, which are shown to be absolutely continuous in time. Four equivalent formulations of the problem
in rate form are derived. A strong formulation of the flow rule is obtained by introducing a precise definition of the stress
on the singular set of the plastic strain. 相似文献