共查询到17条相似文献，搜索用时 265 毫秒
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循环荷载作用下黏弹性地基一维固结性状研究 总被引：2，自引：0，他引：2
针对单层黏弹性地基模型,对循环荷载作傅立叶级数展开,由固结方程求得循环荷载作用下不透水（透水）边界饱和软黏土一维固结解析解。通过不同渗透系数、黏滞系数和弹性模量以及黏弹性与弹性不同地基模型比较等对有效应力的影响,进行了固结性状分析。结果表明、在循环荷载作用下地基中各点的有效应力并不随荷载的变化而同步变化,而是按一定规律滞后发展;有效应力最终达到一个稳定状态,每一个加载卸载循环下有效应力幅值在一个振荡周期的平均值变化趋近于0;软黏土的流变特性对固结的影响主要发生在中、后期。 相似文献
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循环荷载作用下黏弹性地基一维固结性状研究 总被引：1，自引：1，他引：0
针对单层黏弹性地基模型,对循环荷载作傅立叶级数展开,由固结方程求得循环荷载作用下不透水 (透水) 边界饱和软黏土一维固结解析解.通过不同渗透系数、黏滞系数和弹性模量以及黏弹性与弹性不同地基模型比较等对有效应力的影响,进行了固结性状分析.结果表明、在循环荷载作用下地基中各点的有效应力并不随荷载的变化而同步变化,而是按一定规律滞后发展;有效应力最终达到一个稳定状态,每一个加载卸载循环下有效应力幅值在一个振荡周期的平均值变化趋近于0;软黏土的流变特性对固结的影响主要发生在中、后期. 相似文献
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基于Terzaghi一维固结理论,分析了考虑半透水边界条件的分数阶导数黏弹性饱和土层在随时间变化的任意荷载作用下一维固结问题。首先,应用Laplace变换联立求解饱和土层一维固结微分方程和分数阶Kelvin-Voigt黏弹性本构方程,推导出有效应力和沉降在Laplace变换域内的解析解,采用Crump方法进行Laplace逆变换,得到了时间域内的半解析解。然后将本文得到的半解析解分别退化为半透水边界条件下基于黏弹性假设的一维固结半解析解和双面透水边界条件下基于分数阶黏弹性假设的一维固结半解析解,结果与已有文献的半解析解相同,验证了本研究所提出解的可靠性。最后通过算例分别考察了半透水边界参数、分数阶黏弹性模型参数和荷载参数对饱和土层固结沉降的影响。研究表明,半透水边界条件参数、分数阶次与黏滞系数主要影响饱和土层固结的发展快慢,而饱和土层的最终沉降量主要受到土层压缩模量的影响;另外,饱和土层的固结规律与外荷载变化规律一致。 相似文献
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在考虑软黏土流变特性的基础上,结合工程实际,引入连续排水边界条件,建立了变荷载下连续排水边界黏弹性地基一维固结模型。通过分离变量法与常数变易法,求得了变荷载作用及连续排水边界条件下的饱和软黏土一维固结模型的解析解,进一步研究了透水边界条件和土体参数对超孔隙水压力、有效应力的影响。研究结果表明:上下边界透水性的不同会直接影响超孔隙水压力的变化;越靠近透水性大的边界处的土体固结速度越快,且随着其离排水边界的距离减小,对固结速度的影响逐渐增大;另外,软土层的渗透系数、Kelvin体弹簧的弹性模量和黏滞系数等对土颗粒间的有效应力影响较大。 相似文献
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《岩土力学》2017,(11):3240-3246
将分数阶微积分理论引入Kelvin-Voigt本构模型,以描述黏弹性饱和土体的力学行为。对饱和土体一维固结方程和上述分数阶导数Kelvin-Voigt本构方程实施Laplace变换,联立求解得到变换域内有效应力和沉降的解析解。采用Crump方法实现Laplace数值反演,从而获得了物理空间一维固结问题的半解析解,并将其退化到弹性和黏弹性两种经典情形,分析表明,它与经典解析解完全相同,这证明了经典弹性和黏弹性解析解可视为本研究提出分数阶导数黏弹性解的特例。开展了参数研究,即分析了相关各种参数对固结沉降的影响。研究表明,瞬时荷载情形下分数阶导数黏弹性饱和土体一维固结最终沉降量与黏滞系数和分数阶次无关,而不同黏滞系数和分数阶次对固结时间有较大影响。其研究结果有助于深入认识黏弹性饱和土体的固结力学行为。 相似文献
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双层黏弹性地基一维固结分析 总被引：3，自引：0，他引：3
软土具有黏滞性,对其固结和变形会产生一定程度的影响。采用现有基于广义Voigt流变模型的单层黏弹性地基一维固结问题求解方法,获得各土层的孔压通解表达式。根据两层土体接触面处孔压和流量连续条件及边界条件,给出了系统的正交关系,进而确定通解中待定系数。广义Voigt模型反映了土体应力应变关系在不同时期的特征,因此该解有广泛的适用性。采用岩土工程中应用较广的Merchant流变模型对一工程算例进行了分析。分析结果表明,土体的黏滞性降低了土体的固结速度,且深度越深,影响幅度越大。 相似文献
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This paper presents a general solution to the consolidation system of viscoelastic soil by vertical drains incorporating a fractional-derivative model and arbitrary time-dependent loading. The fractional-derivative Merchant model is introduced to describe the viscoelastic behavior of saturated soil around the vertical drains. Based on this model, the governing partial differential equation of a consolidation system incorporating vertical and horizontal drainage is obtained for the equal strain condition. Then, a general solution to the consolidation system involving arbitrary time-dependent loading is derived using the Laplace transform technique and eigenfunction expansion method. Further, two comparisons are presented to verify the exactness of the proposed solution, and the consolidation behavior involving four time-dependent loadings is illustrated and discussed. 相似文献
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为描述饱和土体的流变特性,引入分数阶导数Kelvin-Voigt黏弹性模型,采用解析方法对半透水边界下的分数阶黏弹性饱和土一维固结特性进行了研究。分别对骤加恒载下饱和土一维固结微分方程和分数阶Kelvin-Voigt黏弹性本构方程进行Laplace变换,并联立求解得到了双边半透水边界条件下分数阶黏弹性饱和土在Laplace变换域内的解析表达式。通过Crump方法实现Laplace数值反演,得到时间域内的半解析解。将所得到的解分别退化为分数阶黏弹性饱和土一维固结半解析解和双边半透水黏弹性饱和土一维固结半解析解,结果与已有文献半解析解相同,验证了提出的双边半透水边界条件下分数阶黏弹性饱和土一维固结解的可靠性。通过算例考察了半透水边界条件和分数阶黏弹性饱和土参数对一维固结特性的影响。研究表明,双边半透水边界下分数阶黏弹性饱和土一维固结发展过程与半透水边界条件、分数阶次和黏滞系数有关,且土体的压缩模量对饱和土一维固结最终沉降量有显著影响。 相似文献
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复杂荷载作用下考虑下卧层三维渗流的未打穿竖井地基固结分析 总被引：2，自引：0，他引：2
针对任意复杂变荷载作用下未打穿的竖井地基,通过在竖井底面以下土层中设置虚拟竖井,使其能够合理考虑下卧层土体三维渗流问题,运用Laplace变换,求得频域内竖井地基的固结解。通过Laplace逆变换,得到了任意荷载作用下竖井地基的平均固结度、孔压消散曲线、沉降曲线。结合具体算例,对影响竖井地基固结的主要影响因素进行了详细分析,并将现有未打穿竖井地基平均固结度近似计算方法的精度和适用的范围进行了对比,得到了一些有益于工程实践的结论。 相似文献
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This paper presents a semi-analytical solution to one-dimensional consolidation equation of fractional derivative Kelvin-Voigt viscoelastic saturated soils subjected to different time-dependent loadings. The theory of fractional calculus is first introduced to Kelvin-Voigt constitutive model to describe consolidation behavior of viscoelastic saturated soils. By applying Laplace transform upon the one-dimensional consolidation equation of saturated soils, the analytical solutions of effective stress and settlement in the Laplace transform domain are obtained. The present solutions are more general and have good agreements with available solutions from the literature, and are degenerated into ones for one-dimensional consolidation of elastic and viscoelastic saturated soils. 相似文献
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This paper presents analytical solutions to the one‐dimensional consolidation problem taking into consideration the rheological properties of clayey soil under variable loadings. A four‐element rheological model is introduced, and different loading types are involved, i.e. constant loading, one‐step loading, triangular loading, rectangular loading, and isosceles–trapezoidal cyclic loading. The differential equations governing consolidation are solved by the Laplace transform. Based on the solutions obtained, the influences of the rheological parameters and loading conditions on the consolidation process are investigated. It has been shown that the consolidation behavior is mainly governed by four dimensionless parameters, a1, a2, b, and Tv0. Load shape has a great influence on the rate of consolidation. A decrease either in the modulus of the spring in the Kelvin body or in the viscosity coefficient of independent dashpot will slow down the rate of consolidation. An increase in the viscosity coefficient of the dashpot in the Kelvin body will make the rate of consolidation increase at an early stage but decrease at a later stage. For isosceles–trapezoidal cyclic loading, the consolidation rate in each cycle reaches a maximum at the end of the constant loading phase and the minimum at the end of this cycle. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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This paper presents a semi-analytical solution to one-dimensional consolidation of viscoelastic unsaturated soils with a finite thickness under oedometric conditions and subjected to a sudden loading. The solution is obtained by using Lee’s correspondence principle based on the semi-analytical solution to one-dimensional consolidation of elastic unsaturated soils. The boundary contains the top surface permeable to water and air and the bottom impermeable to water and air. A typical example is given to show the evolution of excess pore-air and pore-water pressures as well as the total degree of consolidation of the soil layer with time for different ratios of air–water permeability coefficient, elastic modulus and viscoelastic coefficient. The one-dimensional consolidation behavior of viscoelastic unsaturated soil is discussed according to the semi-analytical solution. These results contribute to a better understanding of the consolidation behavior of viscoelastic unsaturated soils. 相似文献