加筋方式对黄土动力特性影响三轴试验研究

为探讨黄土动力特性受加筋方式的影响，利用GDS动态三轴测试系统，以玻璃纤维单丝窗纱为筋材，开展了4种围压下10种不同加筋方式的黄土动力特性试验，研究了黄土动弹性模量和阻尼比随围压、加筋位置、加筋层数的变化规律。结果表明:未加筋和加筋试样动弹性模量都随动应变增加呈指数衰减，但随围压增加而增大；应变小于0.05%时，阻尼比分布较离散，应变大于0.05%时，阻尼比随围压和动应变增加而增大；筋材的加入提高了土样的动弹性模量，并有效降低了阻尼比。通过构建加筋效用规格化系数并对比发现:加筋效益受围压与动荷载传播方向影响最为显著；中等围压下筋材发挥效益最明显；对本试验土样尺寸而言两层加筋效果较佳；动静荷载作用下土体中筋材布置都应优先考虑土样2/3～3/4附近。

Influence of the reinforce scheme on dynamic properties of the reinforced loess with dynamic triaxial test

In order to explore influence of the reinforce scheme (position, layers) on dynamic properties (dynamic modulus of elasticity, damping ratio) of reinforced loess, a series of dynamic triaxial were conducted under 4 different confinement pressures and 10 different reinforce schemes. The results show that for both the reinforced and unreinforced loess, the dynamic modulus of elasticity decays exponentially with the increase of dynamic strain, but Ed rises with the increasing confinement pressure. When dynamic strain is less than 0.05%, the damping ration shows discrete distribution. While dynamic strain is large than 0.05%, the damping ratio goes up with the increaseing confinement pressure and dynamic strain. The reinforce material efficiently improves the dynamic modulus of elasticity and reduces the damping ratio. By establishing and comparing the normalized parameters of reinforce effectiveness, this paper illustrates that the reinforcement performance is affected significantly by the confinement pressure and load propagation direction and under medium confinement pressure the reinforcement shows better performance. In terms of the sample size of this test, 2 layers of reinforcement shows best performance. Under both the static and dynamic load, putting the reinforce material at 2/3 to 3/4 position of the loess sample will have better performance than other positions.