Li Zhaoyan, Zhang Liping, Zhuang Haiyang, Wu Qi
Institute of Engineering Mechanics, China Earthquake Administration, Harbin 150080, China.
Institute of Geotechnical Engineering, Nanjing Tech University, Nanjing 210037, China.
Materials (Basel). 2022 Dec 14;15(24):8938. doi: 10.3390/ma15248938.
To investigate the static and dynamic characteristics of rubber-sand composite soil (RS soil) reinforced with cement, a series of triaxial compression tests and resonant column tests was performed by considering the influence of rubber content (10%, 20%, 30%, 40%, and 50%), cement content (0, 1.5, 2.5, 3.5 and 4.0 g/100 mL), and effective consolidation confining pressure (50, 100, and 150 kPa). Compared with the RS soil, the addition of cement significantly improved the shear strength of a cement-rubber-sand composite soil (RCS soil), based on an undrained shear test. The increase in cement content not only makes the elastic modulus and cohesion of the RCS soil increase but also reduces the internal friction angle of the RCS soil. With the increase in rubber content, the failure of the RCS soil samples changes from strain-softening to hardening, and the prediction equation of the initial elastic modulus of the RCS soil is given herein when the recommended cement content is 3.5 g/100 mL. The effects of rubber content, cement content, and effective confining pressure on the dynamic shear modulus and damping ratio of the RCS soil were studied via the resonant column test. The test results show that the increase in rubber content slows down the modulus attenuation of the RCS soil, but increases its damping ratio. The test results also show that the increase in cement content makes the bonding force between particles greater so that the modulus attenuation of the RCS soil becomes slower and the damping ratio is reduced. At the same time, according to the change rule of the maximum dynamic shear modulus of the RCS soil with the rubber content, when the recommended cement content is 3.5 g/100 mL, an empirical formula and recommended value of the shear modulus of the RCS soil are proposed.
为研究水泥增强橡胶砂复合土（RS土）的静动力特性，考虑橡胶含量（10%、20%、30%、40%和50%）、水泥含量（0、1.5、2.5、3.5和4.0 g/100 mL）以及有效固结围压（50、100和150 kPa）的影响，进行了一系列三轴压缩试验和共振柱试验。基于不排水剪切试验，与RS土相比，水泥的添加显著提高了水泥橡胶砂复合土（RCS土）的抗剪强度。水泥含量的增加不仅使RCS土的弹性模量和黏聚力增大，还降低了RCS土的内摩擦角。随着橡胶含量的增加，RCS土样的破坏从应变软化转变为硬化，当推荐水泥含量为3.5 g/100 mL时，给出了RCS土初始弹性模量的预测方程。通过共振柱试验研究了橡胶含量、水泥含量和有效围压对RCS土动剪切模量和阻尼比的影响。试验结果表明，橡胶含量的增加减缓了RCS土的模量衰减，但增大了其阻尼比。试验结果还表明，水泥含量的增加使颗粒间的黏结力更大，从而使RCS土的模量衰减变慢，阻尼比降低。同时，根据RCS土最大动剪切模量随橡胶含量的变化规律，当推荐水泥含量为3.5 g/100 mL时，提出了RCS土剪切模量的经验公式和推荐值。
