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海岛有机质浸染砂液化特性振动台试验研究

Shaking-Table Tests on the Liquefaction Characteristics of Organic Matter-Disseminated Sand in Island Areas

  • 摘要: 针对海岛区域性砂土,开展不同砂样、不同峰值加速度条件下的自由场地振动台试验,结合试验现象与响应数据阐述砂土液化特性,并对其影响因素进行分析。结果表明: 2种砂土地基均发生变形沉降,伴有喷沙冒水等液化现象;超静孔压比与加速度呈现正相关性,随着埋深的增加,液化风险降低;有机质浸染砂超静孔隙水压力消散速率慢且有残存,标准砂超静孔隙水压力消散速度快且彻底;加速度放大系数呈现高程放大效应,加速度放大系数随加速度增加而增大;循环剪应力随加速度的增加而上升,有机质浸染砂显示出在相同条件下更高的液化风险;显著性分析表明加速度对砂土液化的影响高于埋深。

     

    Abstract: Sand soli liquefaction can significantly reduce the bearing capacity of foundations, posing risks to the structural integrity of buildings and infrastructure. In this study, free-field shaking table tests were conducted to evaluate the liquefaction behavior of regional sandy soils from island environments under various sand types and acceleration conditions. The liquefaction characteristics of the sandy soil were analyzed by integrating macroscopic phenomena, pore pressure measurements, and acceleration data obtained from the tests. The results indicate that under seismic excitation, both types of sandy soil foundations experience deformation and settlement while exhibiting liquefaction phenomena such as flow failure, sand spouting, and water gushing. The ratio of excess pore pressure is positively correlated with peak loading values, while liquefaction susceptibility decreases with greater burial depth. Notably, organic matter-disseminated sand demonstrates slower excess pore pressure dissipation and persistent residual pressures, whereas standard sand exhibits rapid and complete dissipation. Acceleration measurements reveal a bottom-to-top amplification effect within soil layers. The amplification coefficient for acceleration increases alongside higher peak loading values, demonstrating a more pronounced amplification effect in shallower soil layers. Additionally, the cyclic stress ratio (CSR) rises with increased loading intensity, and organic matter-disseminated sand presents a heightened risk of liquefaction under identical conditions. Significance analysis underscores that acceleration magnitude exerts a greater influence on liquefaction potential than burial depth.

     

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