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Geotechnical engineering applications are characterized by various sources of uncertainties, most of them attributed to the stochastic nature of soil parameters and their properties. In particular, soil’s inherent random heterogeneity, inexact measurements and insufficient data necessitate numerical methods that incorporate the stochastic soil properties for a realistic representation of the soil behavior. In this paper, the process of consolidation of saturated soils is examined on the basis of the coupled u–p finite element formulation. A generalized Newmark implicit time integration scheme is implemented to treat the time integration of the coupled consolidation equations. A benchmark geotechnical engineering problem of a strip footing resting on a saturated soil layer is analyzed. The soil permeability coefficient k, as well as the elastic modulus E, are treated as lognormal random fields in two dimensions. The investigation of the effect of the spatial variability of the soil properties on the response of a footing–soil system is examined by means of the direct Monte Carlo simulation. The influence of the coefficient of variation and correlation length of the stochastic fields is quantified in terms of footing settlements, as well as excess soil water pore pressure. The effects of spatial variability of the permeability coefficient k and the elastic modulus E on the system response are demonstrated. It is shown that the footing differential settlement, along with generated excess pore pressures, is highly affected by the variation of the soil properties considered, as well as the correlation length of the underlying random fields. 相似文献
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针对复合地基固结问题,考虑井阻和土体径竖向渗流的影响,建立 以"桩-土-桩"为单元的复合地基群井计算模型,采用解析解法,推导出瞬时载荷作用下复合地基群井固结解析解,讨论了复合地基固结特点和孔压等的变化规律。研究表明,复合地基群井固结模型为复合地基固结理论的研究提供了一种新思路,在井径比大于5 时,基于中心桩、边桩流量相等假设,复合地基群井固结理论所求固结度和传统固结理论所求固结度相差很小,可忽略不计;桩体渗透系数、内外扰动区土体径向渗透系数、土体竖向渗透系数越大,复合地基固结速率越快;堆载越大,最终达到稳定时的沉降量和竖向应变越大;地基表层土体的孔压消散速率和竖向应变速率大于地基深部土体。 相似文献
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在作者已建立的饱和多孔介质耦合非线性热弹性理论基础上,考虑热渗效应,建立了饱和多孔介质耦合热弹性固结方程,并推导了有限长圆柱热固结问题的解析解,进而以温控三轴试验的试样为例进行了算例分析,同时利用COMSOL软件进行了数值模拟,并将解析结果和数值结果进行对比.结果表明:在不排水条件下,影响试样最终孔压大小的参数是:土的泊松比>弹性模量>水的体膨胀系数,渗透系数对孔压变化影响不大,考虑与不考虑水土压缩性不影响孔压的计算;相对线弹性情况,考虑非线弹性膨胀系数随温度变化时的孔压有所下降,轴向应变变化很小. 相似文献
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由于多层地基的一维非线性固结问题求解的复杂性,其解析解很难求得。本文基于Davis和Raymond一维非线性固结理论,利用DQM(Differential Quadrature Method)导了初始有效应力沿深度变化、任意边界条件、任意荷载作用下成层地基一维非线性固结的统一表达式,求得了孔压、有效应力和平均固结度的解答。通过解的收敛性分析讨论了DQM解的有效性。由于DQM解对于固结间题各种复杂条件具有统一的矩阵表达式,更便于编程计算和工程应用。最后,用本文解答对三层地基一维非线性固结问题进行了讨论。 相似文献
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This paper presents an alternative analytical technique to study a plane strain consolidation of a poroelastic soil by taking into account the anisotropy of permeability. From the governing equations of a saturated poroelastic soil, the relationship of basic variables for a point of a soil layer is established between the ground surface (z=0) and the depth z in the Laplace-Fourier transform domain. Combined with the boundary conditions, an exact solution is derived for plane strain Biot's consolidation of a finite soil layer with anisotropic permeability in the transform domain. Numerical inversions of the Laplace transform and the Fourier transform are adopted to obtain the actual solution in the physical domain. Numerical results of plane strain Biot's consolidation for a single soil layer show that the anisotropic of permeability has a great influence on the consolidation behavior of the soils. 相似文献
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One-Dimensional Consolidation of Layered and Visco-Elastic Soils under Arbitrary Loading 总被引:1,自引:0,他引:1
IntroductionAfterTerzaghi,alotofscholarshavedoneoutstandingresearchontheproblemsofone_dimensionalconsolidation .Wilson ( 1974) [1] andBaligh( 1978) [2 ] etal.havestudiedtheconsolidationundertherectangularloading .In 1988,WUetal.[3] workedoutthegeneralsolutionsofone_dimen… 相似文献
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Based on Biot’s dynamic consolidation equations,by means of Laplace-Hankel transform technology,the integral solutions of stress and displacement in saturated soil with subjacent rock-stratum under axisymmetric arbitrary excitations were derived.In- fluence of the reflected wave generated by the boundary was revealed.Numerical results indicate that the vibration frequency has some effect on the vertical displacement of satu- rated soil.The vertical displacement at the surface of saturated soil lags in phase with the load.Furthermore,the dynamic permeability coefficient of saturated soil has significant effect on the vertical displacement at the initial stage of load applied,but when the load becomes stable,the effect is inapparent. 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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Vivien J. Challis James K. Guest Joseph F. Grotowski Anthony P. Roberts 《International Journal of Solids and Structures》2012,49(23-24):3397-3408
We compute Pareto fronts that estimate the upper bounds of the bulk modulus and fluid permeability cross-property space for periodic porous materials over a range of porosities. The fronts are generated numerically using topology optimization, which is a systematic, free-form design algorithm for optimizing material layouts. The presented microstructures demonstrate the trade-off between the bulk modulus and fluid permeability achievable with a multifunctional porous material and will be useful for designers of materials for which both stiffness and permeability are important. Our results suggest that the range of achievable stiffness and permeability properties is significantly restricted when considering elastic isotropy, as compared to cubic elastic symmetry. The estimated bounds are of practical importance given the lack of microstructure-independent theoretical cross-property bounds. 相似文献
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土-基础相互作用隔震体系地震随机响应分析 总被引:13,自引:0,他引:13
视地基土为各向同性的弹性半空间,用弹簧-粘性阻尼器模拟土对结构的影响,将地震激励模拟为平稳随机过程,对基础隔震体系的随机响应进行了分析。分析结果表明,地基土的性质对隔震结构有直接影响,但其影响比非隔震结构小得多。 相似文献
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Efficient and robust iterative methods are developed for solving the linear systems of equations arising from stochastic finite element methods for single phase fluid flow in porous media. Permeability is assumed to vary randomly in space according to some given correlation function. In the companion paper, herein referred to as Part 1, permeability was approximated using a truncated Karhunen-Loève expansion (KLE). The stochastic variability of permeability is modeled using lognormal random fields and the truncated KLE is projected onto a polynomial chaos basis. This results in a stochastic nonlinear problem since the random fields are represented using polynomial chaos containing terms that are generally nonlinear in the random variables. Symmetric block Gauss-Seidel used as a preconditioner for CG is shown to be efficient and robust for stochastic finite element method. 相似文献
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考虑桩体内径向渗流的复合地基固结解 总被引:4,自引:0,他引:4
考虑了桩体内径竖向组合渗流和涂抹区土体水平渗透系数的两种变化模式,得到了此类固结问题的控制方程.采用新的初始条件,得到了控制方程的解答,给出了桩周土体和桩体内的平均孔压.在此基础上,把桩体的固结压缩引人对复合地基总平均固结度的定义中,分别给出了复合地基按应力和按应变定义的总平均固结度.结果表明:按应力和按应变定义的复合地基的总平均固结度相等;考虑桩体内径向渗流比不考虑桩体内径向渗流的复合地基固结度要小,而且随着桩间距的增大,两者之间的差值逐渐减小;考虑涂抹区水平渗透系数逐渐变化比假定涂抹区水平渗透系数保持不变的复合地基的总平均固结度大. 相似文献
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《Acta Mechanica Solida Sinica》2017,(6)
An analytical method is developed to investigate the dynamic response of a pile subjected to harmonic vertical loading.The pile is modeled as a one-dimensional(1D)elastic rod.The elastic soil is divided into a homogeneous half space underlying the base of pile and a series of infinitesimally thin layers along the vertical shaft of pile.The analytical solution for the soil-pile dynamic interaction problem is obtained by the method of Hankel transformation.The proposed solution is compared with the classical plane strain solution.Arithmetical examples are presented to demonstrate the sensitivity of the vertical impedance of the pile to relevant parameters. 相似文献
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