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Numerical direct shear tests for outwash deposits with random structure and composition

机译:具有随机结构和成分的冲刷沉积物的数值直接剪切试验

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摘要

Outwash deposits is a kind of special geological material composed of soil and stone particles. Since the shear behaviors of outwash deposits are mainly dominated by its complicated structure and composition the strength parameters of which are difficult to be determined accurately. In this work, samples of outwash deposits with random structure and composition taking account of the effects of sizes, shapes and distributions of stone blocks were simulated based on the granular discrete element method. The meso-scale parameters of soil and stone particles were first calibrated by comparing numerical predictions with experimental data. Then a series of numerical direct shear tests for the simulated samples were conducted. Results show that the effects of strain hardening of shear stress-displacement curves become increasingly apparent with the increase of stone content. The shear strength of outwash deposits is dominated by the content as well as by the random distribution of stone blocks. There is an approximate linear relationship between the mean value of shear strength and the stone content lying between 30 and 60 %, while a larger fluctuation in shear strength mainly due to the random distribution of stone blocks. Compared with the mean value of shear strength, the maximum fluctuation of internal friction angle reaches up to 4.26° while the maximum fluctuation of cohesion approximates up to 1/3 of its mean value. Results also indicate that the improvement of cementation degree between soil particles increases mainly the macro cohesion of outwash deposits but has almost no influence on the macro internal friction angle. And because of a relative higher strength of stone blocks, the shear yield bands of outwash deposits detours significantly around stone blocks and shows numerous local cracks, which frequently accompanies an acute release of strain energy owing to the geometric redistribution of stone blocks. The integration of laboratory investigations and numerical direct shear tests can be an effective approach to determine the statistical mechanic's parameters of outwash deposits.
机译:冲积物是一种由土壤和石头颗粒组成的特殊地质物质。由于外洗沉积物的剪切行为主要受其复杂的结构和成分支配,其强度参数难以准确确定。在这项工作中,基于颗粒离散元方法,模拟了具有随机结构和组成的洗出沉积物样本,并考虑了石块的大小,形状和分布的影响。首先通过将数值预测与实验数据进行比较来校准土壤和石头颗粒的中尺度参数。然后对模拟样品进行了一系列数值直接剪切试验。结果表明,随着石材含量的增加,剪切应力-位移曲线的应变硬化效应越来越明显。外洗沉积物的剪切强度主要取决于其含量以及石块的随机分布。剪切强度的平均值与石材含量在30%至60%之间存在近似的线性关系,而剪切强度的较大波动主要归因于石材的随机分布。与抗剪强度的平均值相比,内摩擦角的最大波动高达4.26°,而内聚力的最大波动则约为其平均值的1/3。结果还表明,土壤颗粒间胶结度的改善主要增加了冲积沉积物的宏观内聚力,但对宏观内摩擦角几乎没有影响。并且由于石块的相对较高的强度,冲刷沉积物的剪切屈服带在石块周围明显地弯曲并且显示出许多局部裂缝,由于石块的几何重新分布,这常常伴随着应变能的急剧释放。将实验室研究与数值直接剪切试验相结合可以成为确定冲洗沉积物统计力学参数的有效方法。

著录项

  • 来源
    《Granular matter》 |2014年第5期|771-783|共13页
  • 作者单位

    Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China, Institute of Geotechnical Engineering, Hohai University, Nanjing 210098, China;

    Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China, Institute of Geotechnical Engineering, Hohai University, Nanjing 210098, China;

    Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China, Institute of Geotechnical Engineering, Hohai University, Nanjing 210098, China;

    Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China, Institute of Geotechnical Engineering, Hohai University, Nanjing 210098, China;

    Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China, Institute of Geotechnical Engineering, Hohai University, Nanjing 210098, China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Outwash deposits; Random structure and composition; Numerical direct shear tests; Shear strength; Granular discrete element method;

    机译:冲洗沉积物;随机的结构和组成;数值直接剪切试验;剪切强度;颗粒离散元法;

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