许多土工建筑破坏都与土的抗拉强度密切相关,抗拉强度是土体重要的力学指标之一。与土的抗剪强度和抗压强度相比,土体抗拉强度从试验仪器到理论均不成熟。分析现有测量土体抗拉强度的仪器优缺点,自行研制了可自动读取数据的平卧式土工拉伸仪;针对特殊形状试样的饱和需求,对传统重叠式饱和架进行改进,设计了一种通用型重叠式饱和器。利用自制仪器进行在不同初始干密度、饱和度、含砂量下的含砂黏性土抗拉强度试验,分别探讨了各种因素对抗拉强度的影响。结果表明:抗拉强度随干密度的增加呈线性增加,随土体饱和度的增加先增加后减小且在饱和度为0.6左右达到峰值,随含砂量的增加先缓慢减小且在含砂量达到20%后迅速减小,含砂量>40%后抗拉强度逐渐趋于0。进而建立了抗拉强度与各影响因素之间的函数表达式。研究成果对实际工程中含砂黏性土抗拉强度的确定具有一定参考价值。
Abstract
The damage of many geotechnical buildings is closely related with the tensile strength of soil, which is a crucial mechanic indicator of soil. Nevertheless, compared with shear strength and compressive strength, tensile strength still lacks mature test instruments and theories. In this study, tensile strength tests were conducted on sandy clayey soil specimens with varied dry density, saturation degree, and sand content using self-made test equipment. The influences of these factors on the results of tensile strength were examined. The self-made instruments include a horizontal extensograph which reads data automatically, and a universal superimposed saturator which meets the requirements of specimens of special shapes. Results revealed that with the rising of dry density, tensile strength increased linearly; but with the rising of saturation degree, tensile strength increased and then declined, and reached peak at saturation degree of 60%; with the augment of sand content, tensile strength reduced slowly at first, and such reduction intensified when sand content reached 20%, and then tensile strength approached zero when sand content exceeded 40%. On this basis, the functional relations of tensile strength against the influential factors were established. The research findings offer reference for determining the tensile strength of sandy clayey soil in practical engineering.
关键词
含砂黏性土 /
抗拉强度 /
单轴拉伸试验 /
干密度 /
饱和度 /
含砂量
Key words
sandy clayey soil /
tensile strength /
uniaxial tensile test /
dry density /
saturation degree /
sand content
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基金
三峡大学硕士学位论文培优基金项目(2019SSPY034);中国地质调查局项目(DD20190716)
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