Subgrade fill strength and bearing characteristics of weathered phyllite blended with red clay
Subgrade fill strength and bearing characteristics of weathered phyllite blended with red clay
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DOI：
10.1080/14680629.2020.1773906
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发表时间：
2020-06
影响因子：
3.7
通讯作者：
Xiushao Zhao;Zhitao Fu;Qijing Yang;Kai Yao;D. Geng;Kai Li
中科院分区：
文献类型：
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作者：
Xiushao Zhao;Zhitao Fu;Qijing Yang;Kai Yao;D. Geng;Kai Li
摘要本文介绍了将全风化千枚岩（CWP）与当地开采的红粘土以不同的掺合比掺合以提高路基填料抗剪强度和承载力的系统研究结果。制备了不同弯曲比的CWP土样，进行了击实试验、微针入渗试验和直剪试验。研究了红粘土掺入比、含水率和压实系数对煤矸石粘土抗剪强度的影响。微渗透试验结果表明，微渗透强度增长模式有三种类型。结果表明，在一定的含水率和压实系数下，随着红粘土掺量的增加，红粘土的抗剪强度和极限承载力均有所提高。建立了三次多项式函数模型，预测了不同掺合比条件下煤矸石与红粘土混合土的极限承载力和粘聚力。利用土的微观结构分析结果，对强度增长的三个阶段进行了预测，并对这一现象的机理进行了分析。结果表明，红粘土的加入增加了土体中的粘粒含量，增强了土粒间的铁胶结作用。在一定掺合比下，极限承载力随压实系数线性增加，随含水率线性减小。基于Bzz-100荷载标准，建立了混合路基填料极限承载力计算模型，提出了满足城市道路承载力要求的混合土优化方案。现场试验和应用结果表明，本文提出的优化方案不仅能提高水泥稳定土的承载力，而且能降低红粘土的开裂潜力。
ABSTRACT This study presents the results of a systematic investigation on enhancing the shear strength and bearing capacity of subgrade fill by blending the completely weathered phyllite (CWP) with locally won red clay at varying blending ratios. Many CWP soil samples were prepared at varying bended ratios for carrying out a compaction test, micro-penetration test and direct shear test. The effects of the red clay blending ratio, moisture content (w) and compaction coefficient (K) on the shear strength of CWP clay were also been investigated. Micro-penetration test results show that there are three types of micro-penetration strength growth patterns. It is found that, at a given set level of moisture content and compact coefficient, an increase of red clay in the blending ratio result in a higher shear strength and the ultimate bearing capacity. Cubic polynomial function models were developed to predict the ultimate bearing capacity and cohesion of the CWP blended soils with the red clay at varying blending ratios. The observed three stages of strength growth can be predicted, and the mechanism of this phenomenon has been analyzed using the results from soil micro-structure analysis. It has been found that the addition of red clay increases clay content within the soil mass and enhances iron cementation among the soil particles. At a given blending ratio, the ultimate bearing capacity increases linearly with the compaction coefficient and decreases linearly with moisture content. The ultimate bearing capacity calculation model of blended subgrade fill was developed based on the Bzz-100 load standard, and the optimum schemes of blending soils were proposed to meet the requirement of urban road bearing capacity. Field trials and applications show that the optimum scheme proposed in this paper can not only improve the bearing capacity of CWP, but also reduce the cracking potential of red clay.