基于黏弹性理论的沉桩再固结问题分析

发布时间：2018-05-30 02:15

本文选题：沉桩 + 软土　；参考：《岩土力学》2015年03期

【摘要】：假设桩周土体为饱和黏弹性介质,采用Burgers流变模型进行描述,同时考虑竖向和径向固结,建立了固结控制方程。根据不排水和自由排水情况,将边界条件分为3类并分别得到超孔隙水压力消散的级数解答,该解答能够为孔压静力触探反求固结系数提供一定的理论依据。在此基础上编制了应用程序,对Burgers流变模型中主要参数进行了分析。结果表明,地基表面自由排水、桩端地基不排水条件下,在一定深度以内的桩周土体的固结速度随深度降低,但超过某一范围后固结速度趋于稳定;上、下边界均自由排水条件下,固结速度随深度增加呈现下降、稳定、升高;上、下边界均不排水条件时,孔压消散速度不随深度变化,可简化为本解答仅考虑径向固结的特例。同时土体的流变特性对超孔隙水压力消散的影响比较显著,流变参数G1/1的变化使超孔隙水压力趋于某不为0的定值,且该值随G1/1比值的增大而增加;其他参数不变时,土体剪切刚度比G1/G2的增大会引起孔压消散速度的下降。
[Abstract]:Assuming that the soil around the pile is a saturated viscoelastic medium, the Burgers rheological model is used to describe it, and the consolidation control equation is established by considering the vertical and radial consolidation at the same time. According to the case of undrained and free drainage, the boundary conditions are divided into three categories and the series solution of excess pore water pressure dissipation is obtained respectively. The solution can provide a certain theoretical basis for the inverse calculation of consolidation coefficient by hydrostatic penetration of pore pressure. On this basis, an application program is developed to analyze the main parameters in the Burgers rheological model. The results show that under the condition of free drainage on the surface of the foundation and undrained condition of the pile-end foundation, the consolidation velocity of the soil around the pile within a certain depth decreases with the depth, but after a certain range the consolidation velocity tends to be stable. Under the condition of equal free drainage of the lower boundary, the consolidation velocity decreases, stably and increases with the increase of depth, while the dissipation velocity of pore pressure does not change with the depth when the upper and lower boundaries are not drained, which can be simplified as a special case in which radial consolidation is only considered in this solution. At the same time, the rheological characteristics of soil have a significant effect on the dissipation of excess pore water pressure. The change of rheological parameter G _ 1 / 1 makes the excess pore water pressure tend to a certain fixed value, which increases with the increase of G _ 1 / 1 ratio. The increase of shear stiffness ratio (G1/G2) results in the decrease of the velocity of pore pressure dissipation.
【作者单位】：上海大学土木工程系;
【基金】：国家自然科学基金资助项目(No.11272200)
【分类号】：TU473.1

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