微生物固化橡胶颗粒改良土的力学特性研究

RESEARCH ON MECHANICAL PROPERTIES OF RUBBER-PARTICLE-IMPROVED SOIL CEMENTED BY MICP

微生物固化能有效提高砂土的强度,而橡胶颗粒与砂土组成的橡胶颗粒土相比于纯砂而言,具有密度小、弹性变形能力强、耗能大、弹性模量低等特点,故提出微生物橡胶颗粒改良土的方法。通过无侧限抗压强度试验,得到微生物橡胶颗粒改良土的强度特性,并分析了橡胶颗粒含量对微生物诱导碳酸钙沉淀技术的影响,基于共振柱试验,重点对比研究橡胶含量、围压对混合土动剪切模量和等效阻尼比的影响。结果表明:当橡胶含量在一定范围(3%左右)内,能够提高混合土的无侧限抗压强度。围压和橡胶颗粒的含量是影响掺橡胶固化钙质砂试样动剪切模量和阻尼比的主要因素;相同配比下,围压越高,动剪切模量越大,衰减越慢,阻尼比越小;在围压不变的情况下,橡胶含量越多,动剪切模量衰减越慢,阻尼比越大。

Microbial-induced calcite precipitation(MICP)can effectively improve the strength of sand,while rubber-particle sand compacted with sandy soil is of low densities,strong elastic deformation capacity,high energy dissipation capacity and low elastic modulus than that of pure sand.Therefore,a method of improving soil combined with rubber particles and the MICP tachnique was proposed.The influence of rubber-particle contents on microbial induced calcium carbonate precipitation was analyzed.Based on the resonant-column test,the effects of rubber contents and confining pressure on dynamic shear modulus and equivalent damping ratios of the mixed soil were compared.The unconfined compressive strength of the mixed soil could be improved when the contents of rubber particles were in a cartain range(about 3%).The confining pressure and the contents of rubber particles were the main factors affecting the dynamic moduli and damping ratios of the soil.The higher the confining pressure,the greater the dynamic modulus and the slower the attenuation of damping ratios,and the smaller the damping ratios;under the constant confining pressure,the higher the rubber contents,the slower the attenuation of the dynamic modulus,and the larger the damping ratios.