土工格栅加筋橡胶砂应力-应变特性试验

Stress⁃strain characteristics of geogrid reinforced rubber sand mixtures

基于静三轴剪切试验,分析了5种配比(0%、10%、20%、30%、40%)、4种格栅布置方式(无筋、水平1层、水平2层、水平3层)、3种围压(50、100、200 kPa)下土工格栅加筋橡胶砂的应力-应变关系特性和模量衰减特性。结果表明:(1)土工格栅加筋使得橡胶砂应力-应变关系曲线明显升高,加筋后橡胶砂的硬化特性增强。(2)采用扩展邓肯-张模型进行拟合,随着橡胶颗粒含量的增加,橡胶砂初始模量降低,模量衰减程度可由衰减参数定量反映;模量曲线衰减程度随加筋工况“水平3层加筋、无筋、水平2层加筋、水平1层加筋”依次增大。(3)土工格栅加筋使得橡胶砂的参考应变增大、应力-应变模型指数减小,即模量归一化应力应变曲线非线性程度减弱,随着土工格栅加筋密度和配比的增大,土工格栅对橡胶砂应力应变特性的加筋效应更显著。

Based on the static triaxial shear test,the stress-strain characteristics,the modulus attenuation properties,and the normalized stress-strain behavior of reinforcing rubber sand mixtures were analyzed.Five kinds of rubber content(0%,10%,20%,30%,and 40%),four kinds of geogrid reinforcing patterns(lateral arrangement with no layer/one layer/two layers/three layers),and three kinds of confining pressure(50 kPa、100 kPa、200 kPa)were taken into account in tests.Results indicate that①The geogrid reinforcement makes stress-strain curves of rubber sand mixture raised obviously,and the hardening characteristics of the reinforced specimens are enhanced.②The stress-strain behavior of the rubber sand mixture could be simulated well by the extended Duncan-chang hyperbola model,and the model parameters are evaluated with rubber content in the rubber sand mixture. With the increase of rubber content, the initial modulus of the rubber sand mixture decreases, and the attenuation parameters can quantitatively reflect the degree of modulus attenuation. The attenuation degree of rubber sand mixture increases for geogrid reinforcing cases lateral arrangement with three layers/no layer/two layers/one layer,but the overall difference is insignificant. ③ With the use of geogrid reinforced, the reference strain of the rubber sand is increased while the index of the stress-strain model is decreased. To illustrate, the degree of nonlinearity of the normalized stress-strain curve of the modulus is weakened. With the increase of the geogrid-reinforced density and rubber content, the reinforcement effect of geogrid on the stress-strain characteristics of rubber sand is more significant.