大变形固结理论连续性条件的严格表述

A Strict Form of Continuity Condition in Largestrain Consolidation Theory

摘要:

基于连续介质力学有限变形理论,提出了欧拉描述情况下,一维大变形固结连续性条件的严格表述形式.其中,控制变量分别选择常用的Almansi应变和孔隙比两种情况.分析结果表明,以往根据简化形式的连续性条件得到的Almansi应变及其物质时间导数的计算值均偏小,容易导致对地基沉降变形的估计不足.传统分析中将Almansi应变的物质导数直接用作土体瞬时体积变化率,这种度量方法理论上应当予以修正.

关键词:软粘土层; 大变形; 固结; 连续性条件; 欧拉描述; Almansi应变

Abstract:

Based on finite deformation theory of continuum mechanics,a strict form of continuity condition for onedimensional largestrain consolidation problems is proposed in terms of Eulerian description.The usual governing variables such as Almansi strain and void ratio are discussed respectively to establish a new strict form of continuity condition.The results show that the conventional simplified continuity condition can predict smaller values of both Almansi strain and its material time derivative,thus leading to a considerable underestimate of foundation settlement.It’s necessary to modify the conventional method of taking material derivative of Almansi strain directly as instantaneous rate of volume change of soil mass.

Key words:soft clay; largestrain; consolidation; continuity condition; Eulerian description; Almansi strain