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层状饱水软土地基三维非轴对称动力响应分析方法 总被引：1，自引：0，他引：1
将饱水软土地基视为两相介质、考虑水的渗流和土骨架9变形的耦合作用，用Fourier展开和Hankel积分变换分析三维非称对称饱和弹性土层波动方程，用刚度矩阵方法，建立了层状饱和软土地基三维非轴对称动力响应的解析分析方法。以数值算例对比分析了单相土介质与两相饱和土介质三维非轴对称稳态动力响应，结果表明：在饱水软土地基动力响应分析中应该考虑土体中孔隙流体的影响。 相似文献
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根据笔者的饱和流体孔隙介质中波的传播理论,具体研究了地震波在含水地层中的耗散和弥散效应。数值结果表明,影响地震波在含水地层中传播的重要因素,除频率外,是固相骨架和水的弹性波阻抗的比值和介质的渗透性、孔隙率;而固相颗粒与固相骨架的可压缩性的差别因素则影响较小。估计了含气量对波传播速度的影响。指出了迄今在地球物理学中的震相分析,工程地震学中的测震结果的分析和解释,以及在地力学中处理动力问题时把含水地层按单相材料考虑都可能存在很显著的误差,需要考虑到孔隙流体（水,气）的存在和根据具体情况做些相应的修正。 相似文献
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地震动斜入射条件下海洋场地简化为理想流体海水-两相介质海床-弹性固体基岩系统模型,通常假定为静水液面条件。本文以地震动SV波为例,推导了表面波条件下海洋场地动力反应解析解,研究了表面波条件对海水动水压力的影响。研究表明,表面波频率在大于0.5Hz时对海水动水压力几乎无影响,在小于0.5Hz范围内有影响,且越接近水面、频率越低时影响越显著。实际地震动卓越频率通常大于0.5Hz,因而地震动作用下采用忽略表面波条件的静水液面假定是合理的。进一步结合线性波浪理论,研究SV波和波浪联合作用下表面波条件对海水动水压力的影响。研究表明,由于波浪属于低频荷载且频率通常小于0.5Hz,在地震和波浪联合作用下表面波条件的影响较地震单独作用更为显著。 相似文献
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文中对含两种不相混流体的饱和孔隙介质模型进行了波场模拟,该模型基于封闭型系统假设,考虑了流相与固相的相对运动和孔隙率、饱和度(毛细管压力)的松弛机制,可以较好的模拟波场的数值衰减。与目前常用的等效流体方法和基于开敞系统假设的非饱和孔隙介质模型相比,更符合勘探阶段的实际情况。前人对该介质模型平面波的速度和衰减做了一定的研究,但对整个波场的计算研究还未见报道。本文推导了该模型包含毛细管压力和孔隙度松弛机制的波动方程,并利用有限元的方法进行了波场模拟,并对波场特征进行了分析。数值模拟结果表明,在地震频段,非湿相位移波场中慢波p3较为清晰;毛细管压力(饱和度)和孔隙度的松弛效应对非湿相流体位移有较大影响,随松弛系数的增大,位移减小。 相似文献
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本文基于Biot理论,推导出Zoeppritz形式的双相介质分界面上弹性波的反射与透射公式,对单相Zoeppritz公式与双相反射系数公式进行了比较,对双相介质含油、水、气不同流体时的反射规律以及孔隙度、渗透率、饱和度等储层参数对纵波反射的影响进行了研究.数值模拟分析表明,双相与单相反射公式的主要差异在于双相介质反射公式中考虑了液相、固液耦合相弹性模量的影响;油砂、水砂、气砂岩的慢P波反射差异明显;快P波反射对孔隙度的变化敏感,饱和度次之,对渗透率和频率的变化不敏感. 相似文献
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本文以一海洋深水环境桩柱为例,考虑到海洋地基为两相饱和土介质,基于Biot两相饱和多孔介质理论,通过数值算例分析了饱和介质中瑞利波加速度、位移分布规律并与单相弹性介质地基条件下进行了对比,结果表明,瑞利波主要作用于地表附近且振动幅度随深度衰减很快,饱和地基下的瑞利波影响深度要大于单相弹性地基,在瑞利波地震作用下,考虑两相饱和介质下的桩柱位移响应大于单相弹性介质地基。并且由于桩柱处海洋深水环境,本文对环境水体对桩柱振动响应的影响进行了研究,结果表明,流固耦合效应可明显降低桩柱运动响应,在海洋深水环境地震响应分析时,有必要考虑饱和地基以及流固耦合效应对桩柱运动响应的影响。 相似文献
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传统基于单相介质理论的储层参数反演方法将孔隙流体与固体骨架等效为单一固体,弱化了孔隙流体的影响,反演结果精度不高.本文提出根据双相介质理论反演储层参数的方法.首先,在前人研究的基础上,利用岩石物理模型建立弹性参数与孔隙度、饱和度、泥质含量等储层参数间的关系,进而将双相介质反射系数推导为储层参数的函数;其次,根据贝叶斯反演理论,在高斯噪声假设的基础上,采用更加符合实际情况的修正柯西分布函数描述反射系数的稀疏性,推导出储层物性参数目标反演函数;最后,应用差分进化非线性全局寻优算法来求解目标反演函数,使得反演结果与实际资料间误差最小.新方法旨在突出流体对介质反射系数的影响,以期得到较高的储层参数反演精度.模型与实际资料测试均表明该方法可行、有效且反演精度较高. 相似文献
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地下固体介质弹性模量是固体地球定量表征的重要参数,是探测地球内部结构、地下流体分布、设计合理工程方案的关键之一.本文首先简要分析常用的流体饱和孔隙介质岩石物理模型,在此基础上通过数值计算,详细讨论了流体饱和多孔介质等效弹性模量对固体基质、孔隙度、孔隙结构和孔隙流体的敏感性,探讨了利用等效介质弹性模量反演固体基质弹性模量的可行性,建立了固体基质弹性模量的非线性方程系统,提出了该方程系统的数值迭代求解方法,并通过对三类岩石样本实验室测量数据的反演和结果分析,验证了方法的有效性.文中同时通过不同条件下对实验数据的反演,探讨了孔隙结构、孔隙流体和等效介质弹性模量对反演效果的影响,为方法的合理有效应用提供依据. 相似文献
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Wave reflection and refraction in layered media is a topic closely related to seismology, acoustics, geophysics and earthquake engineering. Analytical solutions for wave reflection and refraction coefficients in multi-layered media subjected to P wave incidence from the elastic half-space are derived in terms of displacement potentials. The system is composed of ideal fluid, porous medium, and underlying elastic solid. By numerical examples, the effects of porous medium and the incident wave angle on the dynamic pressures of ideal fluid are analyzed. The results show that the existence of the porous medium, especially in the partially saturated case, may significantly affect the dynamic pressures of the overlying fluid. 相似文献
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以Biot饱和多孔介质动力学理论为基础,利用Fourier Bessel级展开法,给出了饱和多孔介质半空间中半球形凹陷地形对入射平面SV波散射问题的解析解.利用这一解析解数值计算地表位移幅值,分析入射角、入射波频率对地表位移幅值的影响,并与现存的单相介质情况下三维半球形凹陷问题解析解进行对比得出如下结论：(1)本文两相介质模型与单相介质模型有很大区别;(2)入射角、入射频率对场地表面位移分量有重要影响;(3)随着入射角、入射频率的增大,地表位移分布变得更复杂,且放大效应比单相介质模拟结果更加显著. 相似文献
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This paper presents an analytical solution for two-dimensional scattering and diffraction of plane P waves by circular-arc alluvial valleys with shallow saturated soil deposits. The solution is based on Biot's dynamic theory for saturated porous media, and derived by employing Fourier–Bessel series expansion technique. In this analysis, soil deposits in the circular-arc valley are modeled as saturated porous media based on Biot's dynamic theory, and the circular-arc valley is assumed to be imbedded in an infinite half-space, filled with elastic single-phase media. Numerical results from this solution show that the amplitudes of displacement at the surface of an alluvial valley are mainly relative to the angle of incidence, the dimensionless frequency of incident P wave, the degree of saturation and porosity of soil deposits, and the stiffness and Poisson's ratio of the solid skeleton of the soil deposits. Furthermore, the proposed solution is compared with the previous solution, in which the soil deposit was modeled as an elastic single-phase solid. 相似文献
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Based on the dynamic theory for saturated porous media by Biot (Journal of the Acoustical Society of America 1956; 28 : 168–178), a numerical model is presented to analyse the reflection behaviours of reservoir sediment and compared with those from the visco‐elastic model. It is concluded that the two models give very similar results of reflection coefficient α within the frequency range of interest. Then, using the two models, the change of the reflection coefficients α with various sedimentation parameters and excitation frequencies are studied in detail. The results are further used in the analysis of response functions of hydro‐dynamic pressures on, and structural displacements of the Xiang Hong Dian arch dam, for which some results from a field vibration test are available. It appears that effects of water compressibility with sediment reflection on hydro‐dynamic pressures and structural response are not significant for this specific case. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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The effects of the interaction among sea water, sediment, backfill-soil and coastal structures (embankments) were included in the present study. The formulation is derived from fundamental theories in various fields, including marine hydrodynamics, flow in porous medium, and structural dynamics. The hybrid finite-difference and finite element methods were used in the analysis. The finite-difference method was used to calculate the nonlinear hydrodynamic pressures of sea water as well as the pore water in the sediment acting on the coastal embankment faces by seismic-wave actions. The fluid-filled solid mixture was used to model sediment and back-fill soil and the corresponding dynamic responses were also evaluated by finite difference method. The dynamic response of the coastal structures was calculated by finite element method. The numerical results are presented for various water depths and ground motion intensities. The significant dynamic forces on coastal structures were calculated during earthquakes and the possible sliding of the coastal embankment will occur and the special foundation treatment should be made. 相似文献
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Influence of water saturation on horizontal and vertical motion at a porous soil interface induced by incident P wave 总被引：2，自引：0，他引：2
This paper describes a study on the influence of water saturation on horizontal and vertical motion at the interface between porous soil and rock formation due to an incident P wave. The soil is modeled as a partially water-saturated porous material with a small amount of air inclusions, while the underlying rock is approximately regarded as an ordinary one-phase solid. Theoretical formulation is developed for the computation of motion amplitudes in both horizontal and vertical components, which are considered as functions of the degree of saturation, the angle of incidence as well as the frequency. Numerical results are provided to illustrate the effect of saturation on displacement amplitudes in both components and their ratios. The results show that even a slight decrease of complete saturation may lead to a substantial change in the motion amplitudes in both horizontal and vertical components. In general, partial saturation may cause lower horizontal-to-vertical ratios over the entire range of incident angles except the normal incidence, implying the potential importance of saturation effects in the interpretation of field observations. 相似文献
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A computational procedure for two-dimensional finite-element analysis of dam–water–sediment–rock systems subjected to seismic excitations is reviewed. In particular, the semidiscrete approximation of the water–sediment–rock region on the upstream side of the dam by means of a hyperelement is described in detail. The sediment is represented in the hyperelement as a fluid-filled porous solid on the basis of the Biot theory of wave propagation in poroelastic media while the water is taken as a compressible, inviscid fluid and the rock as a viscoelastic solid. An application of the procedure to a study of the effects of sediment porosity and thickness on the response of a model dam to horizontal and vertical ground motions is presented and discussed. 相似文献