土工格室加筋对橡胶砂动力特性影响的试验研究

Experimental study on influence of geo-cell reinforcement on dynamic properties of rubber-sand mixtures

橡胶砂作为轻质耗能填料在土木工程中应用越来越广泛,土工格室加筋可提高橡胶砂的抗剪强度和整体稳定性。针对关于橡胶砂或加筋橡胶砂动力特性的认知缺乏的现状,通过大尺寸循环单剪试验研究了橡胶砂分别在有无土工格室加筋情况下在水平循环荷载作用下的滞回特性。获得了加筋和非加筋橡胶砂的滞回曲线、动剪模量曲线和阻尼比曲线,并应用Stokeo–Darendeli模型对橡胶砂动力特性进行拟合,得到了加筋和非加筋橡胶砂的动力特性参数。基于对比分析,揭示了土工格室对橡胶砂动力特性影响的规律与机理。试验结果表明:(1)土工格室加筋能限制橡胶砂中剪切带的发展,使得橡胶砂在大应变下的滞回曲线反S形特征减弱、阻尼比增大;(2)由于网兜效应引起颗粒接触法向应力增大,土工格室加筋使橡胶砂动剪模量增大,且随着橡胶含量的增高而增大愈明显;(3)土工格室的加入降低了循环加载次数对橡胶砂动力特性的影响,并使得橡胶砂最大动剪模量随橡胶含量和竖向压力变化的速率减小。给出的土工格室加筋对橡胶砂动力特性影响的定量分析结果,可为后续研究和工程应用提供参考。

The rubber-sand mixtures （RSM） are more and more widely used in civil engineering as light filling and energy absorbing materials. The geo-cell can be used to reinforce RSM to improve its shear strength and stability. Little knowledge has been reported on the dynamic properties of RSM or geo-cell reinforced RSM （GCRSM）. Based on this, the hysteretic properties of RSM with or without geo-cell reinforcing under cyclic horizontal loadings are investigated through large-size cyclic simple shear tests. The hysteretic curves, dynamic shear modulus curves and damping ratio curves of RSM and GCRSM are obtained by tests and fitted by the Stokeo-Darendeli model to gain parameters of dynamic properties. The comparative analysis of dynamic properties between RSM and GCRSM is carried out, and the rules and mechanisms of how the geo-cell influences the dynamic properties of RSM are verified. The test results show that： （1） Owing to the restriction of local shear band development in the specimen by the geo-cell, the S-shaping characteristics is less pronounced and the damping ratio increases under large strains when comparing GCRSM to RSM. （2） The dynamic shear modulus of RSM is increased by the geo-cell reinforcement, and the increment becomes more pronounced with addition of rubber content of RSM, which is believed due to the normal stress increment between particles in RSM caused by tuck net effect of geo-cell. （3） The influence of cycle numbers on dynamic properties of RSM decreases with use of geo-cell reinforcement. The decay velocity of the maximum dynamic shear modulus of RSM with both rubber content and vertical pressure is reduced when the geo-cell is used to reinforce RSM. Quantitative influences of geo-cell reinforcement on the dynamic characteristics of RSM are also provided for reference of the following researches and engineering applications.