Some Bearing Capacity Characteristics of a Structured Naturally Deposited Clay Soil
Some Bearing Capacity Characteristics of a Structured Naturally Deposited Clay Soil
复制标题
结构化自然沉积粘土的一些承载力特性
DOI：
10.3208/sandf.47.285
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发表时间：
2007
影响因子：
3.7
通讯作者：
S. Yamada
中科院分区：
文献类型：
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作者：
T. Noda;A. Asaoka;S. Yamada
采用基于非常规弹塑性力学的土水耦合有限变形分析方法，对结构化自然沉积粘土的承载力特性进行了研究。土骨架的本构方程采用超/次加载屈服面Cam-clay模型（SYS Cam-clay模型）来表达，这是作者提出的一种弹塑性本构方程模型，用于描述骨架结构中的作用机制（结构、超固结和各向异性）。为了从理论上考虑典型的承载力问题，假设了通过具有摩擦力的刚性基础施加垂直位移的情况。研究的主要结论是：（1）在高度结构化的土壤中，荷载-沉降关系出现峰值，并伴随着相当大的局部应变和清晰可见的滑移线。在初始各向异性较高的土壤中，破坏区域更加有限，并且峰值载荷比初始各向同性土壤更小。 (2) 对于具有初始缺陷的高度结构化土壤，即使缺陷非常轻微，也会发生敏感响应，导致不对称变形模式。同时，荷载-沉降曲线与同一土体对称变形时的路径“分叉”，从而表现出更大的荷载下降。 (3) 如果将荷载从土壤中几乎不会发生孔隙水迁移的快速速率（≒完全不排水）放宽到较慢的速率，峰值荷载将随着部分排水效应而逐渐增加。如果进一步降低负载速率，最终将达到观察不到负载下降的点，并且无法区分故障区域的清晰边界。根据加载速率，可能会看到由应变局部区域的土壤结构腐烂引起的压实带的清晰外观。这些发现旨在表明，在此类分析中纳入土壤骨架结构的概念不仅是一个非常自然的步骤，而且也是一个最重要的进步。
An investigation was conducted into the bearing capacity characteristics of a structured naturally deposited clay soil by means of a soil-water coupled finite deformation analysis based on unconventional elasto-plastic mechanics. The constitutive equation of the soil skeleton was expressed using the Super/subloading Yield Surface Cam-clay model (SYS Cam-clay model), an elasto-plastic constitutive equation model proposed by the authors to describe the mechanisms (structure, overconsolidation and anisotropy) at work in the skeleton structure. To allow a theoretical consideration of a typical bearing capacity problem, a case was assumed in which vertical displacement was applied through a rigid foundation possessing friction. The main conclusions of the study were: (1) In a highly structured soil, a peak appears in the load-settlement relation, accompanied by a considerable localization of strain and a clearly visible slip line. In a soil of high initial anisotropy, the area of failure is more confined and the peak load is smaller than in an initially isotropic soil. (2) In the case of a highly structured soil possessing an initial imperfection, even if this is very slight, a sensitive response occurs, leading to an asymmetrical deformation mode. At the same time, the load-settlement curve “bifurcates” from the path the same soil exhibits when it is deformed symmetrically, so as to display a larger decrease in load. (3) If loading is relaxed from a rapid rate (≒ completely undrained), at which virtually no migration of pore water can occur in the soil, to a rate that is slower, the peak load will gradually increase with the partial draining effect. If the rate of loading is reduced still further, a point will eventually be reached where no drop in load is observed and it becomes impossible to distinguish clear boundaries for the area of failure. Depending on the rate of loading, it may be possible to see the clear appearance of a compaction band, caused by soil structure decay in the area of strain localization. These findings aim to show that the inclusion of a concept of soil skeleton structure in an analysis of this sort is not only a very natural step to take, but also an advance of the greatest importance.
“接近/处于临界状态的严重超固结粘土的土水耦合行为”土壤和地基。
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