【摘要】 针对成层Gibson地基模型,研究了半透水边界饱和土层在各种荷载作用下有效应力以及沉降的变化.运用Laplace变换求得了频域内有效应力在任意荷载作用下的解,并结合数值Laplace逆变换,对几种常见的荷载作用下的固结进行了讨论,通过具体算例研究了各土性参数对固结的影响.在实际工程计算中,应根据土层和垫层的具体情况,确定边界条件属于完全透水、半透水或不透水,从而得到更为准确的结果.循环荷载作用下成层Gibson地基固结,其有效应力和变形都呈振荡增长,由于水的存在,两者的变化步调不与荷载同步,这一点与弹性单相介质在循环荷载作用下的规律不同.对于双面排水地基,靠近土层上下表面处应力振荡幅值较大,滞后时间较小;本文计算模型中假设压缩模量只随深度变化,不随时间变化,因此有效应力及变形振荡较大,而实际工程中,由于压缩模量随加载过程的顺延有增长趋势,故可以想像随时间增长,时间有效应力和变形的振荡幅度将减小.更多还原

【Abstract】 By the method of Laplace transform on the one- dimensional consolidation of saturated layered Gibson soils (assuming that the modulus of compressibility increases linearly with depth) with semi- pervious boundaries under arbitrary loading;the study yielded the general solution in the Laplace transform field,from which the effective stress in the soils under arbitrary loading can be calculated by the Laplace inversion. According to a numerical example, some characters of consolidation of elastic soils were found. The drainage condition of boundaries must consider the actual condition of the soils and cushion layer in engineering practice. Reasonable estimation of the drainage condition of the boundary will lead to accurate results. When the Gibson soils consolidates under cyclic loading, the effective stress and deformation fluctuate and increase, but do not synchronize with loading since the affection of the water, which is different with the single- phase medium response under cyclic loading. For soils with double- drainage boundaries, the amplitude of stress near the surfaces is greater and lag time is less. In this paper the compressibility modulus is assumed to change with depth, so the effective stress and deformation fluctuate greatly, but in engineering practice, the compressibility modulus under loading increases with time, so fluctuation amplitude of the effective stress and deformation decreases with time.更多还原