干湿循环与初始静偏应力耦合作用下城市污泥固化土动力累积变形特性

DYNAMIC-TRIAXIAL CUMULATIVE DEFORMATION CHARACTERISTICS OF MUNICIPAL SLUDGE SOLIDIFIED SOIL UNDER THE COUPLING ACTION OF DRY-WET CYCLE AND INITIAL STATIC DEVIATOR STRESS

城市污泥固化土用作路基填料,对于节约工程成本、保护环境等具有重要意义。本文以城市污泥固化土为研究对象,利用DDS动三轴仪,从干湿循环次数、初始静偏应力、动应力3个方面研究其对累积塑性应变及动强度特性的影响。试验结果表明:在干湿循环单独作用下,土体累积塑性应变随干湿循环次数的增加先增大后趋于稳定,但与初始静偏应力耦合作用下对土体累积塑性应变的影响不太显著。动应力对其影响较大,且存在临界值:当动应力小于临界值时,累积塑性应变呈现出先增大后逐渐稳定的趋势;当动应力大于临界值时,累积塑性应变在达到某一振次后快速增大,土体迅速产生变形破坏。干湿循环与初始静偏应力都会降低土体的动强度,但干湿循环在达到10次后,动强度将趋于平稳,不再受其影响。通过回归分析,建立了考虑干湿循环次数、初始静偏应力及动应力等因素影响的城市污泥固化土稳定型累积塑性应变模型,并验证了其可行性。

As subgrade filler, municipal sludge solidified soil is of great significance for saving engineering cost and protecting environment. This paper takes the municipal sludge solidified soil as the research object and uses DDS dynamic triaxial apparatus to study the influence on cumulative plastic strain and dynamic strength characteristics. It considers the three aspects of number of dry and wet cycles, initial static deviator stress and dynamic stress. The experimental results show that the accumulative plastic strain of soil increases first and then becomes stable with the increase of dry-wet cycles under the action of dry-wet cycles alone, but the change of accumulative plastic strain of soil is not obvious under the coupling action of dry-wet cycle and initial static deviator stress. The dynamic stress has a great influence on the cumulative plastic strain and there is a critical value. when the dynamic stress is less than the critical value. The cumulative plastic strain increases first and then becomes stable gradually. When the dynamic stress is greater than the critical value, the cumulative plastic strain increases rapidly after reaching a certain vibration time, which causes rapid deformation and damage of soil. Both the dry-wet cycle and the initial static deviator stress can reduce the dynamic strength of soil. But after the dry-wet cycle reaches 10 times, the dynamic strength can tend to be stable and not be affected by them. By means of regression analysis, we establish a stable cumulative plastic strain model of the municipal sludge solidified soil, which takes into account the influences of the number of dry-wet cycles, the initial static deviator stress and the dynamic stress. We verify its feasibility.