严寒地区高速铁路水泥稳定碎石基床冻胀性能试验研究

Experimental Study on Frost Heaving Properties of Cement Stabilized Macadam Subgrade Bed of High Speed Railway in Severe Cold Regions

采用粗粒土冻胀性能大直径试验装置、岩石多功能试验机和大直径试样渗透仪,进行冻融次数、水泥掺量、颗粒级配对水泥稳定碎石基床冻胀性能、渗透系数及无侧限抗压强度影响规律的试验研究。结果表明：单向冻结条件下,土体的冻结或融化过程可划分为快速降温（升温）、过渡和稳定3个阶段,且在融化初期,土体的中间部分存在冻土核;在保证基床强度满足规范要求的前提下,对于无渗水性要求的路基,基床填料宜选用细粒土含量为3%、水泥掺量为3%的级配碎石;对于有渗水性要求的路基,基床填料宜选用去除0.5mm以下细颗粒、水泥掺量为3%-5%的级配碎石。结合试验结果,运用数理统计等手段,综合考虑细粒含量、颗粒粒径及水泥含量对冻胀率的影响规律,提出冻胀率的计算分析模型。

Large-diameter test device for the frost heaving property of coarse-grained soil,multifunctional rock testing machine and large sample permeameter were adopted to carry out experimental study on the influence of freezing-thawing cycle,cement content and grain composition on the frost heaving properties,permeability coefficient and unconfined compressive strength of cement stabilized macadam subgrade bed.Results show that,under unidirectional freezing,the freezing or thawing process of soil can be divided into rapid cooling（heating）,transitional and stable stages.In the early stage of thawing,frozen-soil core exists in the middle part of soil.On the premise that the strength of subgrade bed can meet code requirements,the filling material for subgrade bed with no water permeability requirement should select graded crushed stone with 3% of fine-grained soil and 3% of cement content.The filling material for subgrade bed with water permeability requirement should select graded crushed stone with no fine grain below0.5mm and 3%~5% of cement content.Based on experimental results and comprehensively considering the influence of fine particle content,particle size and cement content on frost-heave factor,the calculation and analysis model for frost-heave factor is established by means of mathematical statistics.