共查询到19条相似文献，搜索用时 156 毫秒
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采用解析法,以弹性半空间-淤砂层-理想流体层为对象,分别将淤砂层模拟为固体介质和流体介质,分析了平面P波入射时上层理想流体的动力反应特性。通过算例分析,比较了将淤砂层模拟为弹性固体、黏弹性固体、理想流体和黏性流体介质时与将淤砂层模拟为两相多孔介质时计算结果的差异。研究表明当渗透系数很小时,多孔介质可以近似简化为黏弹性固体,甚至线弹性固体。这一分析研究对于在高坝-库水-淤砂-地基系统地震反应分析的数值模型中采用合理的淤砂层模型,提高计算效率具有重要参考意义,而且还可以用于校核数值模型的合理性。 相似文献
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选用三参数标准线性固体作为岩石本构,提出了一种考虑岩体黏弹性的位移不连续模型;根据一维黏弹性波的特征线法,推导了节理处质点速度、应力和应变递推公式。首先,基于分离式霍普金森压杆（SHPB）对砂层进行试验,得到其应力-应变关系,并换算出砂层节理的法向刚度;接着,通过一维强间断黏弹性波的波速公式、高频波衰减系数以及任一频率下的衰减系数,确定出数值算法中的三参数。最后,基于自制的摆锤装置,探讨了一维应力波在节理岩体中的传播规律,试验中以两根长1 000 mm、直径为68.50 m的岩杆作为入射和透射杆,以3 mm砂层模拟节理。试验和数值结果吻合度良好,进一步验证了该方法的可靠性。 相似文献
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基于无黏性可压缩理想流体介质波动理论和Biot流体饱和多孔介质波动理论,考虑水下饱和土的流固耦合,借助Hankel函数积分变换法(HFITM)给出入射平面P1波在海底洞室周围散射问题的解析解。相比传统研究中的"大圆弧假定",Hankel函数积分变换法可以较好地处理半空间表面边界条件。利用该解析解,计算分析了洞室表面透水条件、入射角度、入射频率、海水水深和饱和土的孔隙率等因素对水-土交界面处水平位移、竖向位移和洞室表面动水压力、环周总应力的影响。结果表明:洞室表面透水条件对水-土交界面处水平位移和竖向位移影响较小;随着斜入射角的增加,水-土交界面处竖向位移减小;随着入射频率的增加,水-土交界面处水平位移随之增加;海水水深为2.5倍SV波的波长时,水-土交界面处水平位移及洞室表面动水压力最大值最大;随着孔隙率的增加,水-土交界面处水平位移、竖向位移和洞室表面环周总应力减小,而洞室表面动水压力随之增加。 相似文献
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地下圆形衬砌隧道对沿线地震动的影响(Ⅰ):级数解 总被引：8，自引：4，他引：8
利用波函数展开法，给出了地下圆形衬砌隧道对入射平面P波和SV波散射问题的一个级数解答，当衬砌与半空间介质相同时，该解答退化为文献中的无衬砌隧道的解答。级数解答为进一步定量研究隧道对入射平面P波和SV波的放大作用以及入射波长、入射角度、隧道直径和衬砌刚度等参数对隧道沿线地震动的影响奠定了理论基础。 相似文献
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基于弹性波在冻结饱和多孔介质与单相弹性介质中的传播理论,研究了平面P波在饱和冻土介质与单相弹性介质分界面上的透反射问题。利用Helmholtz矢量分解定理,根据分界面上的边界条件,获得了平面P波从单相弹性介质入射到饱和冻土介质分界面上透反射振幅比的理论表达式。通过数值计算,分析了在不同入射频率、胶结参数、孔隙率、饱和度和接触参数下,弹性波的透反射振幅比随入射角变化的关系。研究结果表明：P波从单相弹性介质垂直入射到饱和冻土介质分界面上时只有反射P波和3种透射P波产生,当掠入射时只产生反射而没有透射现象发生。入射频率、胶结参数、孔隙率、饱和度以及接触参数等参数对反射波和透射波的振幅比影响显著。 相似文献
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含软夹层的层状沉积河谷场地的地震动力响应分析 总被引：1，自引：0，他引：1
把层状沉积河谷场地中的软夹层模拟为流体饱和多孔介质,结合已有的对单相弹性固体介质、流体饱和多孔介质进行动力反应分析的显式有限元方法,建立了既能描述沉积河谷谷底的软土场地（用流体饱和多孔介质描述）,又能描述河谷周边山体（用单相弹性介质描述）的计算模型,并利用该方法分析了研究在P波入射下软夹层厚度以及软夹层的刚度等因素对层状沉积谷场地地震动力响应的影响。 相似文献
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利用波函数展开法,给出了地下圆形衬砌隧道对入射平面P波和SV波散射问题的一个级数解答,当衬砌与半空间介质相同时,该解答退化为文献中的无衬砌隧道的解答。级数解答为进一步定量研究隧道对入射平面P波和SV波的放大作用以及入射波长、入射角度、隧道直径和衬砌刚度等参数对隧道沿线地震动的影响奠定了理论基础。 相似文献
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在考虑横观各向同性含液饱和多孔介质固体骨架和流体可压缩性以及固体骨架的黏弹性特征下,基于横观各向同性含液饱和多孔介质u-w形式的三维动力控制方程,以固相位移u、液相相对位移w为基本未知量,综合运用Laplace变换、双重Fourier变换等方法,在直角坐标系下通过引入中间变量,将六元2阶动力控制方程组化为两组各含4个未知变量的常微分方程组,给出了直角坐标系下横观各向同性含液饱和多孔介质三维黏弹性动力反应的积分形式一般解;作为理论推导的验证,通过引入初始条件和边界条件,对横观各向同性含液饱和多孔介质半空间黏弹性瞬态反应问题进行了求解。解答的退化验证表明,所推导的理论解是正确的。 相似文献
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Traditionally, most formulations of dynamic halfspace problems have represented the material as either an elastic or a viscoelastic solid. Herein the counterpart of Lamb's elastodynamic problem is reformulated and solved for a liquid-saturated poroelastic halfspace using Biot's theory of poroelasticity. The responses of the solid and fluid phases are evaluated due to steady-state harmonic concentrated loads applied to each phase at the surface. The solutions are presented over a broad range of permeabilities and are compared to solutions to Lamb's problem for equivalent drained and undrained solids. Methodology is then introduced by which these results are treated as Green functions for the solution of a mixed boundary-value problem. namely, the response of the poroelastic halfspace to steady-state harmonic vertical motion of a rigid. massless plate. It is observed that small differences exist among overall compliance functions for a drained solid, an undrained solid, and a liquid-saturated porous, halfspace. However, use of the poroelastic model permits the distribution between effective skeletal normal stresses and fluid stresses to be determined. 相似文献
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Three‐dimensional time‐harmonic fundamental solutions for a fluid‐saturated poroelastic half‐space with partially permeable free surface 
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下载免费PDF全文 By virtue of a pair of scalar potentials for the displacement of the solid skeleton and the pore fluid pressure field of a saturated poroelastic medium, an alternative solution method to the Helmholtz decomposition is developed for the wave propagation problems in the framework of Biot's theory. As an application, a comprehensive solution for three‐dimensional response of an isotropic poroelastic half‐space with a partially permeable hydraulic free surface under an arbitrarily distributed time‐harmonic internal force field and fluid sources is developed. The Green's functions for the poroelastic fields, corresponding to point, ring, and disk loads, are reduced to semi‐infinite complex‐valued integrals that can be evaluated numerically by an appropriate quadrature scheme. Analytical and numerical comparisons are made with existing elastic and poroelastic solutions to illustrate the quality and features of the solution. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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The Biot linearized theory of fluid saturated porous materials is used to study the plane strain deformation of a two-phase
medium consisting of a homogeneous, isotropic, poroelastic half-space in welded contact with a homogeneous, isotropic, perfectly
elastic half-space caused by a two-dimensional source in the elastic half-space. The integral expressions for the displacements
and stresses in the two half-spaces in welded contact are obtained from the corresponding expressions for an unbounded elastic
medium by applying suitable boundary conditions at the interface. The case of a long dip-slip fault is discussed in detail.
The integrals for this source are solved analytically for two limiting cases: (i) undrained conditions in the high frequency
limit, and (ii) steady state drained conditions as the frequency approaches zero. It has been verified that the solution for
the drained case (ω → 0) coincides with the known elastic solution. The drained and undrained displacements and stresses are compared graphically.
Diffusion of the pore pressure with time is also studied. 相似文献
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M. D. Sharma 《Journal of Earth System Science》2008,117(6):951-958
Biot’s theory for wave propagation in saturated porous solid is modified to study the propagation of thermoelastic waves in
poroelastic medium. Propagation of plane harmonic waves is considered in isotropic poroelastic medium. Relations are derived
among the wave-induced temperature in the medium and the displacements of fluid and solid particles. Christoffel equations
obtained are modified with the thermal as well as thermoelastic coupling parameters. These equations explain the existence
and propagation of four waves in the medium. Three of the waves are attenuating longitudinal waves and one is a non-attenuating
transverse wave. Thermal properties of the medium have no effect on the transverse wave. The velocities and attenuation of
the longitudinal waves are computed for a numerical model of liquid-saturated sandstone. Their variations with thermal as
well as poroelastic parameters are exhibited through numerical examples. 相似文献
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Consolidation of a poroelastic half-space with anisotropic permeability and compressible constituents by axisymmetric surface loading 总被引：1，自引：0，他引：1
The fully coupled Biot quasi-static theory of linear poroelasticity is used to study the consolidation of a poroelastic half-space
caused by axisymmetric surface loads. The fluid and solid constituents of the poroelastic medium are compressible and its
permeability in the vertical direction is different from its permeability in the horizontal direction. An analytical solution
of the governing equations is obtained by taking the displacements and the pore pressure as the basic state variables and
using a combination of the Laplace and Hankel transforms. The problem of an axisymmetric normal load is discussed in detail.
An explicit analytical solution is obtained for normal disc loading. Detailed numerical computations reveal that the anisotropy
in permeability as well as the compressibilities of the fluid and solid constituents of the poroelastic medium have significant
effects on the consolidation of the half-space. The anisotropy in permeability may accelerate the consolidation process and
may lead to a dilution in the theoretical prediction of the Mandel-Cryer effect. The compressibility of the solid constituents
may also accelerate the consolidation process. 相似文献
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This paper considers the transient response of a pressurized long cylindrical cavity in an infinite poroelastic medium. To obtain transient solutions, Biot's equations for poroelastodynamics are specialized for this problem. A set of exact general solutions for radial displacement, stresses, pore pressure and discharge are derived in the Laplace transform space by using analytical techniques. Solutions are presented for three different types of prescribed transient radial pressures acting on the surface of a permeable as well as an impermeable cavity surface. Time domain solutions are obtained by inverting Laplace domain solutions using a reliable numerical scheme. A detailed parametric study is presented to illustrate the influence of poroelastic material parameters and hydraulic boundary conditions on the response of the medium. Comparisons are also presented with the corresponding ideal elastic solutions to portray the poroelastic effects. It is noted that the maximum radial displacement and hoop stress at the cavity surface are substantially higher than the classical static solutions and differ considerably from the transient elastic solutions. Time histories and radial variations of displacement, hoop stress, pore pressure and fluid discharge corresponding to a cavity in two representative poroelastic materials are also presented. 相似文献
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This paper treats the dynamic response of a multilayered transversely isotropic fluid saturated poroelastic half-space under surface time-harmonic traction. The governing system of partial differential equations is uncoupled with the use of a set of physically meaningful and complete potential functions that decompose different body waves in a saturated poroelastic transversely isotropic medium. After expressing the equations in the Hankel-Fourier domain, a proper algebraic factorization is applied to generate reflection and transmission matrices for decomposed waves. All responses including displacements, stresses, and pore fluid pressure for both general patch load and point load are presented in the form of semi-infinite line integrals. The verification of the method is confirmed with the degeneration of the solutions presented here to the existing solutions for dried both homogeneous and multilayered elastic half-spaces as well as poroelastic half-space. Selected numerical results are depicted to investigate the effects of layering and pore pressure on responses of a transversely isotropic poroelastic medium. The load distribution effects are studied by comparison of the patch and point load responses. Also, resonance notion and effective parameters on this phenomenon such as layering system and anisotropy contrast are discussed. Significant influence of materials and layering configuration on number and amplitude of resonances depicted through the numerical evaluation. 相似文献
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This work addresses in‐plane pressure P and vertically polarized shear SV seismic wave propagation in a finite, laterally inhomogeneous, multilayered poroelastic geological region resting on the homogeneous elastic half‐space. The particular approach followed here is based on a combination of the (i) viscoelastic approximation (isomorphism) to Biot's equations of dynamic poroelasticity and on the (ii) boundary integral equation method (BIEM) using frequency‐dependent fundamental solutions of the governing wave equations. The problem is formulated under plane strain conditions and time‐harmonic motions are assumed. Validation of the viscoelastic isomorphism and verification of the BIEM is done by solution of benchmark examples. These simulation studies reveal that the proposed methodology is able to depict a sensitivity of the seismic signals recovered to the following parameters: (i) poroelastic properties of fluid saturated layers; (ii) lateral geological inhomogeneity; (iii) surface topography and (iv) frequency content and direction of the incident wave. It is concluded that the combination of viscoelastic isomorphism with BIEM software provides an effective numerical tool for evaluating site‐effect phenomena in multilayered, fluid saturated geological regions with complex geometry. The numerical results obtained demonstrate that dynamic poroelasticity interacting with other physical peculiarities of the Earth's surface layers, such as lateral heterogeneity, material properties along the wave path, local geological profile and type of elastic wave, gives rise to complex seismic signals on the free surface at the site of interest. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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This paper develops a semi-analytical solution for the transient response of an unsaturated single-layer poroviscoelastic medium with two immiscible fluids by using the Laplace transformation and the state-space method. Using the elastic–viscoelastic correspondence principle, we first introduce the Kelvin–Voigt model into Zienkiewicz’s unsaturated poroelastic model. The vibrational response for unsaturated porous material can be obtained by combining these two models and assuming that the wetting and non-wetting fluids are compressible, the solid skeleton and solid particles are viscoelastic, and the inertial and mechanical couplings are taken into account. The Laplace transformation and state-space method are used to solve the basic equations with the associated initial and boundary conditions, and the analytical solution in the Laplace domain is developed. To evaluate the responses in the time domain, Durbin’s numerical inverse Laplace transform method is used to obtain the semi-analytical solution. There are three compressional waves in porous media with two immiscible fluids. Moreover, to observe the three compressional waves clearly, we assume the two immiscible fluids are water and oil. Finally, several examples are provided to show the validity of the semi-analytical solution and to assess the influences of the viscosity coefficients and dynamic permeability coefficients on the behavior of the three compressional waves. 相似文献