Freeze-thaw (FT) cycles are regarded as a damage effect to the dynamic resilient modulus () of subgrade soil in seasonal frozen regions and improving the resistance on freeze-thaw cycles must be concerned urgently. For this purpose, the bentonite superabsorbent polymer (BT-SAP) was developed as an available admixture to relieve the attenuation of of subgrade soil under FT cycles. In order to evaluate the improvement of resistance on FT cycles, a series of dynamic triaxial tests were conducted after various FT cycles. The main influences on were investigated including the numbers of freeze-thaw cycles, BT-SAP contents, deviator stress and confining stress. The experimental results indicate that the BT-SAP can delay the attenuation trend of that means the resistance on freeze-thaw cycles have been promoted. The ensuing discoveries are that with the increment of BT-SAP content, the sensitivity of the subgrade soil to FT cycles is gradually reduced. Nevertheless, results reveal that a proper content of BT-SAP is recommended as 0.5%, where if the BT-SAP content exceeds 0.5%, the improvement effect of resistance on FT cycles decreases. Moreover, the improved effect caused by BT-SAP can produce a coupling enhancement combining with confining stress, and it also can offset the softening effect due to the deviator stress. For better application and practicability, the high-accuracy empirical model for predicting is established and validated. Finally, based on the soil freezing temperature, unfrozen moisture content and moisture distribution characteristics, the mechanism of BT-SAP reducing the freeze-thaw cycle sensitivity is analyzed. The conclusions mentioned above show that employing BT-SAP material is acceptable and significant to improve resistance on freeze-thaw of subgrade soil.

中文翻译：

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冻融循环下 BT-SAP 处理路基土的动态回弹模量表征

冻融循环被认为是对季节性冰冻地区路基土动态回弹模量的破坏效应，提高其抗冻融循环能力迫在眉睫。为此，开发了膨润土高吸水性聚合物（BT-SAP）作为一种可用的混合物，以减轻路基土在 FT 循环下的衰减。为了评估 FT 循环阻力的改善情况，在不同的 FT 循环后进行了一系列动态三轴测试。考察了冻融循环次数、BT-SAP含量、偏应力和围应力等对其影响的主要因素。实验结果表明，BT-SAP可以延缓其衰减趋势，提高其抗冻融循环能力。随后的发现是，随着BT-SAP含量的增加，路基土对FT循环的敏感性逐渐降低。然而，结果表明，BT-SAP的合适含量建议为0.5%，如果BT-SAP含量超过0.5%，对FT循环的耐性改善效果会降低。此外，BT-SAP带来的改善效果可以与围应力结合产生耦合增强，并且还可以抵消偏应力引起的软化效应。为了更好的应用和实用性，建立并验证了高精度的预测经验模型。最后，根据土壤冻结温度、未冻结含水量和水分分布特征，分析了BT-SAP降低冻融循环敏感性的机理。上述结论表明，采用BT-SAP材料对于提高路基土的抗冻融性能是可以接受的，且具有重要意义。