水泥稳定碎石基床冻融劣化试验及模型研究

为研究季节性冻土地区高铁路基水泥稳定碎石基床长期冻融循环耐久性,将宏观试验与结构内部微元体的损伤发展相结合,建立了基于Morgan-Mers-Flodin(MMF)模型的高铁路基水泥稳定碎石基床冻融耐久性劣化模型,室内长期冻融循环试验以无侧限抗压强度和抗折强度作为评估水泥稳定碎石材料冻融耐久性的指标.研究结果表明:首先,无侧限抗压强度和抗折强度可表征水泥稳定碎石的冻融耐久性劣化规律;其次,以无侧限抗压强度损失率为控制指标,建立的冻融耐久性预测模型与室内试验保持一致;最后,水泥含量由3％增加至5％时,材料内部抗冻融损伤能力明显提高,建议高铁路基水泥稳定碎石基床水泥掺量为5％.研究结果以期为高铁路基水泥稳定碎石基床强度标准的制定,以及施工和安全运营提供理论支撑.

Tests and Model Studies on the Deterioration of Freeze-thaw of Cement-stabilized Macadam Subgrade Bed in High-speed Railway

In order to study the freezing-thawing durability of high-speed railway subgrade bed in seasonal freezing area. Based on MMF (Morgan-Mers-Flodin) model, a deterioration model of freeze-thaw durability was established by combining the macro tests with the damage development of micro-elements. Unconfined compressive strength and flexural strength were used as the indexes to evaluate the freeze-thaw durability of cement stabilized macadam. The results show that: firstly, unconfined compressive strength and flexural strength can characterize the deterioration law of freeze-thaw durability of cement stabilized macadam. Secondly, the unconfined compressive strength loss rate is used as the damage factor, and the freeze-thaw durability prediction model is highly consistent with the laboratory test data. Finally, the resistance of cement stabilized macadam to freeze-thaw damage is improved obviously when the cement content increases from 3% to 5%. It is suggested that the cement parameter of cement-stabilized macadam subgrade bed in high-speed railway is 5%. The research results are expected to provide theoretical support for the formulation of the strength standard of cement-stabilized macadam in high-speed railway, as well as the construction and safe operation.