Physico-mechanical aspects of liquefaction risk reduction in sand using geotextile-encased granular columns

IF 5.6 1区 工程技术 Q1 ENGINEERING, GEOLOGICAL
Balaji Lakkimsetti, Gali Madhavi Latha
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引用次数: 0

Abstract

Liquefaction-induced flow failures, excessive settlements, lateral spreading, and loss of shear strength in granular soils can become massive hazards during earthquakes. Among the various mitigation techniques available, soil reinforcement using dense granular columns can be considered as a very effective technique, and its effectiveness gets further improved by encasing the columns in a geotextile to maintain the integrity of the columns during earthquakes. This paper presents findings from a first-of-its-kind study of simple shear tests on sand reinforced with geotextile-encased granular columns (EGC) to understand the fundamental mechanisms leading to its improved liquefaction resistance and shearing response. The effects of area replacement ratio and grouping action of columns on the overall response are established by performing a series of multi-stage constant volume simple shear tests on unreinforced and EGC-reinforced sands. The area replacement ratio was varied between 4 and 16% in different tests, and the tests with 16% area replacement ratio were conducted on sand with a single column and a group of columns. The particle sizes, encasement tensile strength, and column configurations are carefully chosen to avoid scaling and boundary effects on the test results. The performance of EGCs against liquefaction was evaluated considering all fundamental mechanisms, including the progression of pore pressures, nonlinear hysteretic behaviour, strain energy accumulation, and shear modulus degradation. The potential of EGCs for mitigating the liquefaction and improving the post-liquefaction shear strength of sand was found to improve with the increase in the area replacement ratio. For a specific area replacement ratio, the beneficial effects were more significant when the EGCs were spread into a group of symmetrically placed columns instead of a single column at the centre. The stress concentration on the EGCs due to modulus contrast and additional confinement offered by the EGCs to intervening soil have collectively benefited the shearing response of sand before, during, and after liquefaction.

Abstract Image

利用土工织物包裹的粒料柱降低砂土液化风险的物理力学问题
在地震期间,由液化引起的流动失效、过度沉降、横向扩展以及粒状土的抗剪强度损失都会造成巨大危害。在现有的各种缓解技术中,使用致密颗粒土柱进行土壤加固可以说是一种非常有效的技术,而将土柱包裹在土工织物中以保持土柱在地震中的完整性,则可以进一步提高其有效性。本文介绍了首次对使用土工织物包裹的颗粒柱(EGC)加固的砂土进行简单剪切试验的研究结果,以了解导致其抗液化能力和剪切响应改善的基本机制。通过对未加固砂和 EGC 加固砂进行一系列多阶段恒定体积简易剪切试验,确定了面积置换比和柱的分组作用对整体响应的影响。在不同的试验中,面积置换率在 4% 和 16% 之间变化,其中面积置换率为 16% 的试验是在有单个柱子和一组柱子的砂子上进行的。为避免试验结果受到缩放和边界效应的影响,对颗粒尺寸、包层抗拉强度和柱体结构进行了精心选择。在评估 EGC 的抗液化性能时,考虑了所有基本机制,包括孔隙压力递增、非线性滞后行为、应变能累积和剪切模量退化。研究发现,随着面积置换比的增加,EGCs 在缓解液化和提高砂土液化后抗剪强度方面的潜力也会提高。在特定的面积置换率下,当电子地质填埋场分布在一组对称的立柱中,而不是位于中心的单个立柱时,其有益效果更为显著。模量对比导致的应力集中在土工格室上,以及土工格室对中间土壤提供的额外约束,共同促进了砂土在液化前、液化过程中和液化后的剪切响应。
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
Acta Geotechnica
Acta Geotechnica ENGINEERING, GEOLOGICAL-
CiteScore
9.90
自引率
17.50%
发文量
297
审稿时长
4 months
期刊介绍: Acta Geotechnica is an international journal devoted to the publication and dissemination of basic and applied research in geoengineering – an interdisciplinary field dealing with geomaterials such as soils and rocks. Coverage emphasizes the interplay between geomechanical models and their engineering applications. The journal presents original research papers on fundamental concepts in geomechanics and their novel applications in geoengineering based on experimental, analytical and/or numerical approaches. The main purpose of the journal is to foster understanding of the fundamental mechanisms behind the phenomena and processes in geomaterials, from kilometer-scale problems as they occur in geoscience, and down to the nano-scale, with their potential impact on geoengineering. The journal strives to report and archive progress in the field in a timely manner, presenting research papers, review articles, short notes and letters to the editors.
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