Effect of smear zone on the consolidation and strength characteristics of soil under radial drainage

IF 1.3 Q3 ENGINEERING, GEOLOGICAL Proceedings of the Institution of Civil Engineers-Ground Improvement Pub Date : 2023-08-18 DOI:10.1680/jgrim.21.00040

R. Aparna, R. Robinson, S. R. Gandhi

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Abstract

Vertical drains installed in soft clay deposits enhance the rate of consolidation in preloading projects. Using a mandrel to install the prefabricated vertical drains (PVD), its insertion and withdrawal will result in the remoulding of the soil zone surrounding it, called the smear zone. The extent of the smear zone is an important parameter that characterizes the smearing effect. This paper describes this effect in terms of smear ratio (i.e., the ratio of the diameter of smear zone ds to the diameter of drain, dw) on the consolidation characteristics of soil with radial drainage. A series of radial consolidation tests with a predetermined smear zone in a model unit cell was conducted by varying the diameter of the smear zone. The experimental results show that beyond a smear ratio of 4, the soil behaves as if it is in a fully remoulded condition. The results were compared with some of the theoretical approaches reported in the literature. The analytical solution that predicts the time-settlement curve in a better way is identified. Also, it is observed that the gain in undrained shear strength due to the consolidation of soft clay decreases with the increase in the diameter of the smear.

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涂抹带对径向排水条件下土体固结及强度特性的影响

在软粘土沉积物中安装垂直排水管，可提高预压工程的固结速度。使用芯轴安装预制垂直排水管(PVD)，其插入和取出将导致周围土壤区域的重塑，称为涂抹区。涂抹区域的范围是表征涂抹效果的一个重要参数。本文从涂抹比(即涂抹区直径ds与排水管直径dw之比)对径向排水土固结特性的影响来描述这种影响。通过改变涂抹区域的直径，在模型单元格中进行了一系列具有预定涂抹区域的径向固结试验。实验结果表明，当涂布比大于4时，土壤表现为完全重塑状态。结果与文献中报道的一些理论方法进行了比较。确定了较好地预测时间沉降曲线的解析解。此外，还观察到由于软粘土固结而获得的不排水抗剪强度随涂布直径的增加而减小。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Proceedings of the Institution of Civil Engineers-Ground Improvement ENGINEERING, GEOLOGICAL-

CiteScore

3.10

自引率

8.30%

发文量

期刊介绍： Ground Improvement provides a fast-track vehicle for the dissemination of news in technological developments, feasibility studies and innovative engineering applications for all aspects of ground improvement, ground reinforcement and grouting. The journal publishes high-quality, practical papers relevant to engineers, specialist contractors and academics involved in the development, design, construction, monitoring and quality control aspects of ground improvement. It covers a wide range of civil and environmental engineering applications, including analytical advances, performance evaluations, pilot and model studies, instrumented case-histories and innovative applications of existing technology.