间歇性循环荷载作用下细粒土的变形特性

铁路路基承受的列车动荷载作用由列车通过时产生的周期性振动和无列车通过时的加载间歇组成, 针对此工程背景，开展不同围压、水的质量分数、动应力条件下的连续加载与加载-停振的动三轴试验，研究间歇性循环荷载作用下细粒土的超孔隙水压力、弹性应变、回弹模量和累积塑性应变的变化规律. 试验结果表明，加载间歇对路基变形特性有显著影响. 由于加载间歇阶段试样卸载以及排水作用，试样在加载阶段积累的超孔隙水压力在间歇阶段消散，土体内部颗粒及结构得到调整，试样抵抗后续荷载的能力得到提高. 此外，加载间歇显著减缓了后续加载阶段的塑性应变发展，降低了试样的累积塑性应变. 加载间歇对提高试样回弹模量、降低弹性应变的效果有限. 加载-停振的间歇加载方式可以更准确地模拟实际列车荷载作用，进而获得更具实际意义的试验结果.

Deformation characteristics of fine-grained soil under cyclic dynamic loading with intermittence

In view of the fact that the dynamic train loading on the railway subgrade is the periodic vibration loading when the train passes and the intermittence when no train passes, a series of continuous and continuous-stopping vibration triaxial tests under different confining pressures, mass fractions of water and dynamic stress conditions were carried out to study the excess pore water pressure, elastic strain, resilience modulus and cumulative plastic strain of fine-grained soil under intermittent cyclic loading. Results show that the loading intermittence has a significant effect on the deformation characteristics of subgrade. Due to the unloading and drainage in the intermittent stage, the excess pore water pressure accumulated in the loading stage dissipates in the intermittent stage, and the particles and structure of the soil are also adjusted, thus the resistance of the samples to subsequent loading is improved. In addition, the intermittent stage significantly slows down the development of plastic strain in the subsequent loading stages and reduces the accumulated plastic strain of samples. However, the intermittent effect on improving the resilience modulus and reducing the elastic strain is limited. The continuous-stopping vibration can better simulate the actual train loads, and provides more practical test results.