基于非达西渗流的饱和黏土一维流变固结分析

ONE-DIMENSIONAL RHEOLOGICAL CONSOLIDATION ANALYSIS OF SATURATED CLAY CONSIDERING NON-DARCY FLOW

为进一步深入探讨饱和黏土的固结机制,引入Merchant流变模型描述其流变固结过程,并同时考虑低速渗流曲线段和较高速渗流直线段的Hansbo渗流方程描述固结过程中的非达西(Darcy)渗流,修正Terzaghi饱和黏土一维固结方程,并给出有限体积法数值求解格式。通过对比已有的Darcy渗流条件下流变固结方程解析解,证明本文数值方法是有效的。然后探讨Hansbo渗流参数和Merchant流变参数对流变固结过程的影响。计算结果表明,渗流的非Darcy特性和流变效应都延缓饱和黏土中孔隙水压力的整体消散速率和地基的沉降速率,同时考虑这2种特性比单独考虑其中任一种特性时达到同一固结度需要的时间要长。而且,考虑流变效应时按变形定义的固结度要小于按孔隙水压力定义的固结度。

To further investigate the consolidation mechanism of saturated clay, the Merchant＇s rheological model is introduced. The Hansbo＇s equation, described by the power function for the lower velocity of flow and the linear function for the higher velocity of flow, is employed to describe the non-Darcy flow. Accordingly, the Terzaghi＇s one-dimensional consolidation equation is modified, and its numerical analysis is conducted by finite volume method. In order to verify its validity, the numerical solution by finite volume method that the flow of pore water obeys Darcy＇s law is compared with the analytical solution based on the one-dimensional rheological consolidation theory in literature. The effects of non-Darcy flow and Merchant model parameters on the rheological consolidation process are investigated. Numerical results indicate that the behaviours of non-Darcy flow and the rheological effects control the dissipation rate of pore water pressure in saturated clay layers, and thereby reduce the settlement rate of these soil layers. For a given degree of consolidation, the consolidation time considering both characteristics is much longer than that considering each of them separately. In addition, the degree of consolidation in terms of settlement is less than that associated with pore water pressure when considering the rheological effect.