近年来废旧轮胎橡胶颗粒与素土混合成轻质土逐渐被用于土工构筑物、路基及挡土墙回填、草坪工程等领域。针对不同橡胶颗粒掺量下橡胶-黏土,采用Shear Trac-Ⅱ剪切仪探讨其在不同竖向压力、剪切速率及橡胶颗粒掺量下的抗剪强度、变形特性,并通过一维固结试验探讨橡胶颗粒-黏土的固结特性。结果表明:黏土的剪切强度随竖向压力、橡胶颗粒掺量增加而增大,但随剪切速率增大而减小,而且剪切速率越大、竖向压力越低越容易发生剪胀变形。随剪切次数增加,橡胶颗粒-黏土的剪切强度达到峰值后出现应变软化现象,最终降至稳定的残余强度,其峰值强度、残余强度较纯黏土分别提高20%和10%,残余内摩擦角较峰值内摩擦角约减小10%,残余黏聚力较峰值黏聚力约降低60%;但达到残余强度所需累计剪切位移随橡胶颗粒掺量增加逐渐增大;此外,相同竖向压力下橡胶颗粒-黏土较黏土的固结时间是黏土固体时间的1/4。试验结果可为改良后黏土用作回填材料、土工构筑物、草坪工程及基础回填等工程提供科学依据。
Abstract
In recent years, lightweight soil composed of scrap tire crumbs and plain soil is applied as the backfill soil for geotechnical structures, subgrades and retaining walls, lawn engineering and other fields. The shear strength and deformation characteristics of rubber-clay mixtures were investigated with ShearTrac-Ⅱ apparatus, with varying shear rate, consolidation pressure and tire crumbs content into account. Moreover, the consolidation characteristics of mixtures were analyzed via one-dimensional consolidation test. Test results indicated that the shear strength of mixtures can be improved by increasing rubber content and consolidation pressure. However, increasing the shear rate would result in the deterioration of shear strength, the larger the shear rate, the lower the consolidation pressure, the more likely of shear dilatancy. As the shearing proceeds, the shear strength of rubber-clay mixture reached peak, displaying strain softening feature, and then declined until reaching a stable residual strength. Compared with those of clay, the peak strength and residual strength of rubber-clay mixture improved by 20% and 10%, respectively; residual internal friction angle reduced by 10% compared with peak internal friction angle; and residual cohesion by 60%. The cumulative shear displacement which is required for reaching residual strength augmented gradually with the increasing of rubber content. In addition, under the same vertical pressure, the consolidation time of rubber-clay mixture shortens by four times compared with that of clay.
关键词
废旧轮胎橡胶颗粒 /
橡胶颗粒掺量 /
黏土 /
剪切强度 /
固结系数
Key words
scrap tire crumbs /
content of tire crumb /
clay /
shear strength /
coefficient of consolidation
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基金
山东科技大学科研创新团队资助项目(2015TDJH104);潍坊学院博士科研启动基金(2019BS18)
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