制样方法对砂土最大动剪切模量的影响研究

    Effect of specimen preparation methods on the maximum dynamic shear modulus of sand

    • 摘要: 砂土的最大动剪切模量是其动力特性表征的关键指标之一,对相关构筑物的抗震安全评价至关重要,但因重塑砂土制样方法及试验级配繁杂,导致砂土最大动剪切模量的影响规律认识不统一,尚待持续研究。本文在中型三轴仪上集成了改进的波速测试装置,开展了多种制样方法(湿夯法、干夯法、空中砂雨法)下重塑砂土的剪切波速试验,探讨了砂土最大动剪切模量的变异规律。结果表明:不同制样方法的砂土在相同固结应力条件下的孔隙比的差异很小,相比其他两种方法,湿夯法制备的试样在低固结应力条件下组构稳定的速率较快,在高固结应力条件下抵抗体积变形的能力较强;制样方法对低固结应力状态下砂土最大动剪切模量的影响较为显著,最大相对差异约为20%,且湿夯法的最大,干夯法的次之,空中砂雨法的最小,但随固结应力的增大,相对差异逐渐减小;虽然通过孔隙比的引入可显著提升砂土最大动剪切模量的推算精度,但不同制样方法对应的参数依然存在较明显的差异,最大相对差异可达到10%以上。

       

      Abstract: The maximum dynamic shear modulus (Gdmax) of sand is one of the key indicators characterizing its dynamic properties, which plays a crucial role in seismic safety evaluations of related structures. However, due to complexities in remolded specimen preparation methods and experimental gradations, the understanding of influencing factors on Gdmax remains inconsistent and requires ongoing research. This study integrated an improved wave velocity testing device into a medium-sized triaxial apparatus to conduct shear wave velocity tests on remolded sand specimens prepared using various methods (moist tamping, dry tamping, and air pluviation), investigating the variation patterns of Gdmax. The results demonstrate that: Specimens prepared by different methods show minimal differences in void ratios under identical consolidation stress conditions. Compared with other methods, moist tamping specimens achieve faster fabric stabilization under low consolidation stresses and exhibit stronger resistance to volumetric deformation under high consolidation stresses. The preparation method significantly affects Gdmax under low consolidation stresses, with maximum relative differences reaching approximately 20% (moist tamping > dry tamping > air pluviation). These differences gradually diminish with increasing consolidation stress. Although introducing void ratio parameters significantly improves the prediction accuracy of Gdmax, parameters corresponding to different specimen preparation methods still show notable differences, with maximum relative discrepancies exceeding 10%.

       

    /

    返回文章
    返回