Freeze-thaw durability of cement-stabilized macadam subgrade and its compaction quality index
Freeze-thaw durability of cement-stabilized macadam subgrade and its compaction quality index
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水泥稳定碎石路基冻融耐久性及其压实质量指标
DOI：
10.1016/j.coldregions.2019.01.005
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发表时间：
2019
影响因子：
4.1
通讯作者：
Zhang Han-bing
中科院分区：
文献类型：
--
作者：
Wang Tian-liang;Song Hong-fang;Yue Zu-run;Hu Tian-fei;Sun Tie-cheng;Zhang Han-bing
水泥稳定碎石路基因其良好的抗冻胀性能，在寒区高速铁路中得到广泛应用。但CSM路基仍存在强度折减、断裂、土粒粉化等问题。因此，本研究的重点是CSM路基的压实指标和强度特性的试验研究。结果表明，掺加水泥可显著改善级配碎石的压实性能。CSM路基的压实质量指标比级配碎石路基高2 ~ 3倍。在强冻融作用下，CSM的无侧限抗压强度和抗弯强度迅速下降；然后，在30次冻融循环后，衰减率逐渐下降并趋于平稳。采用Morgan-Mercer-Flodin生长模型和双曲模型来描述冻融循环对强度的影响。引入弯压强度比来评价CSM的柔度。在强烈冻融作用下，脆性增大，柔韧性减小。最后，综合考虑多种要求，提出了寒冷地区高铁路基水泥掺量5%的方案。
Cement-stabilized macadam (CSM) subgrade is widely used in high-speed railway (HSR) in cold regions owing to its good anti-frost heaving performance. However, the CSM subgrade still encounters some problems such as strength reduction, fractures, and soil-particle pulverization. Hence, this study focuses on the experimental study of compaction indexes and strength properties of CSM subgrade. Results show that admixture of cement significantly improves the compaction performance of graded macadam. The compaction quality indexes of CSM subgrade are 2–3 times higher than those of graded macadam subgrade. Under the effect of intense freezing and thawing, the unconfined compressive strength and flexural strength of CSM decrease rapidly; then, the decay rate declines and levels off gradually after 30 freeze–thaw cycles. The Morgan–Mercer–Flodin growth model and a hyperbolic model were employed to describe the effect of freeze–thaw cycles on measured strength. The flexural-compressive strength ratio was introduced to evaluate the flexibility of CSM. Under intensely freezing and thawing, the brittleness increases and the flexibility decreases. Finally, we proposed 5% cement content for HSR subgrade in cold regions taking multiple requirements into consideration.