不同地区的软黏土会表现出不同的变形特性,研究汕头软黏土在地震循环荷载作用下的变形特性对汕头地区软黏土地基的工程实践具有重要意义。采用英国GDS动三轴仪进行软黏土的动三轴试验,研究在非等向固结不排水条件下,不同固结围压和循环加载应力水平对软黏土的孔压、动应力-动应变、软化指数及累积塑性应变的影响规律。结果表明:固结围压和循环应力比的增大均会加快土体孔压的增长速率和增大土体轴向应变发展;有效固结围压与循环应力比越大,土体软化程度越大,且较大的CSR下土体软化指数会更早趋于平稳;汕头软黏土的累积塑性应变发展曲线在单对数坐标系中可分为以下三种情况,即渐稳型、破坏型和临界型,累积塑性应变发展可用相关的指数修正曲线模型进行拟合,拟合效果较好。研究成果可为汕头地区软黏土地基的工程实践提供参考。
The soft clay in different regions exhibits distinct deformation characteristics. Therefore, investigating the deformation behaviors of Shantou soft clay under cyclic seismic loading is of significant importance for the engineering practice of soft clay foundations in the Shantou area. Dynamic triaxial tests are conducted on soft clay using the GDS dynamic triaxial apparatus from the United Kingdom. The research focuses on the effects of different consolidation confining pressures and cyclic loading stress levels on pore pressure, dynamic stress-strain behavior, softening index, and accumulated plastic strain under non-isotropic consolidation and undrained conditions. The results show that: Both an increase in the consolidation confining pressure and the cyclic stress ratio (CSR) accelerate the growth rate of pore pressure and enhance the development of axial strain in the soil. The higher the effective consolidation confining pressure and CSR, the greater the degree of soil softening. Moreover, under higher CSR values, the soil softening index stabilizes more quickly. The accumulated plastic strain development curve for Shantou soft clay can be classified into three categories in a semi-logarithmic coordinate system: steady-state type, failure type, and critical type. The development of accumulated plastic strain can be well fitted using a corresponding exponential curve model. This study provides valuable insights for the design and construction of soft clay foundations in the Shantou region.
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