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橡胶砂是一种具有潜在广泛应用价值的新型环保岩土材料。为研究橡胶砂在干燥击实、干燥未击实及掺水未击实3种不同初始状态下的直剪特征,对试样(橡胶颗粒、砂、橡胶砂)进行了一系列直接剪切试验,考虑了橡胶颗粒含量及竖向压力对其直剪特征的影响。结果表明:1)干燥击实橡胶砂的剪应力-剪切位移曲线随着橡胶含量的增大由软化型逐渐向硬化型转变;且随着橡胶砂密实性的降低,其剪应力-剪切位移曲线越来越多地表现为硬化型;掺水未击实橡胶砂的剪应力-剪切位移曲线均表现为硬化型。2)竖向压力小于50 k Pa且砂粒密实性较低时,橡胶颗粒可改善砂的强度,最优橡胶含量为20%~40%,且对掺水未击实砂的最优橡胶含量约为10%。3)橡胶砂越密实,越易产生剪胀,湿润橡胶砂比干燥橡胶砂越易产生剪缩。4)不同初始状态对橡胶砂的直剪特征如剪应力-剪切位移曲线、抗剪强度包线、竖向位移-剪切位移曲线的影响随橡胶含量的增大而减弱。
Rubber sand is a kind of new environmentally friendly geotextile material with potential extensive application value. In order to study the direct shear characteristics of rubber sand in three different initial states of dry compaction, dry compaction and water compaction, a series of direct shear tests were carried out on the specimens (rubber particles, sand and rubber sand) , Taking into account the rubber particle content and vertical pressure on the direct shear characteristics. The results show that: 1) the shear stress-shear displacement curve of dry compacted rubber sand gradually changes from softened to hardened with the increase of rubber content; and as the density of rubber sand decreases, the shear stress-shear Displacement curves are more and more show as hardened. The shear stress-shear displacement curve of water-softened un-hardened rubber sand shows hardened. 2) When the vertical pressure is less than 50 kPa and the grit density is low, the rubber particles can improve the strength of the sand, the optimum rubber content is 20% -40%, and the optimum rubber content Is 10%. 3) The more compact the rubber sand, the easier it is to generate dilatancy. The wet rubber sand is more prone to shear shrinkage than dry rubber sand. 4) The influence of different initial conditions on the direct shear characteristics of rubber sand such as shear stress-shear displacement curve, shear strength envelope and vertical displacement-shear displacement curve is weakened with the increase of rubber content.