冻融循环下煤渣改良土细观结构演化研究

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摘要 研究目的: 为研究冻融循环作用对煤渣改良土细观结构的影响,开展不同冻融条件下煤渣改良土的CT扫描试验及三轴压缩试验,获得冻融循环次数、冻结温度、初始含水率不同条件下煤渣改良土孔隙的发展规律及弹性模量演变规律。通过对试样截面的分区观测,分析各区域面积的发展规律,并建立细观结构演化与弹性模量的关系。
研究结论: (1)随冻融循环次数的增加,煤渣改良土试样的内部高密度区面积逐渐减小,中、低密度区面积逐渐增加,孔隙区面积基本保持不变,前5次冻融循环对煤渣改良土结构的影响较大;(2)随冻结温度的降低,煤渣改良土试样高密度区面积出现小幅下降,中、低密度区面积有所增加,但变化程度不大,孔隙区面积基本保持不变,高、中、低密度区面积的变化在-5～-15 ℃之间较为敏感;(3)随含水率的增加,高密度区面积逐渐减小,中、低密度区面积有所增加,孔隙区面积也有一定程度的增加,各区域面积的发展呈加速趋势,单一因素影响条件下,冻融循环次数对试样造成的影响最大,试样初始含水率的影响次之,冻结温度的影响最小;(4)根据冻融损伤因子建立的损伤演化模型具有一定的精度,能较好地反映冻融作用下细观结构演化与弹性模量之间的关系,可为寒区路基冻害防治提供参考。

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	任昆
	王海涛

关键词 ：路基工程, 煤渣改良土, 冻融循环, 细观结构, CT扫描

Abstract：Research purposes: In order to study the effect of freeze-thaw cycles on the micro-structure of cinder improved soil (CIS), CT scanning tests and triaxial tests of CIS under different freeze-thaw conditions were carried out, and the pore development laws and elastic modulus evolution laws of CIS under different freeze-thaw cycles, freezing temperature and initial moisture content were obtained. The development law of each area was analyzed through the zoning observation of the sample section. The relationship between meso-structure evolution and elastic modulus was established.
Research conclusions: (1) With the increase of freeze-thaw cycles, the area of high-density zones decreased gradually, the area of medium-density and low-density zones increased gradually, and the area of pore zone basically remained unchanged. The first five freeze-thaw cycles had a great influence on the structure of CIS. (2) With the decrease of freezing temperature, the area of high-density zones decreased slightly, and the area of medium-density and low-density zones increased slightly, but the change degree is not significant. The area of pore zone remained basically the same. The change of high-density, medium-density and low-density zones were more sensitive in the range of -5℃ ~-15℃. (3) With the increase of moisture content, the area of high-density zones decreased gradually, the area of medium-density and low-density zones increased, and the area of pore zone also increased to a certain extent, and the development of each zone showed an accelerated trend. Under the condition of single factor, the number of freeze-thaw cycles had the greatest influence on the sample, followed by the initial moisture content of the sample, and the freezing temperature had the least influence. (4) The damage evolution model established according to the freeze-thaw damage factor had a certain accuracy, and can better reflect the relationship between meso-structure evolution and elastic modulus under freeze-thaw, which can provide a reference for the prevention and control of subgrade frost damage in cold region.

Key words： subgrade engineering cinder improved soil freeze-thaw cycles meso-structure CT scanning

收稿日期: 2021-06-30

PACS:

U419.92

基金资助:辽宁省教育厅科学研究面上项目(LJKZ0502);大连市高层次人才创新支持计划(2021RQ083)

作者简介: ^**任昆,1988年出生,男,讲师;王海涛,1982年出生,男,教授。

引用本文:

任昆, 王海涛. 冻融循环下煤渣改良土细观结构演化研究[J]. 铁道工程学报, 2022, 39(7): 12-17.
REN Kun, WANG Haitao. Research on the Meso-structure Evolution of Cinder Improved Soil under Freeze-thaw Cycles. Journal of Railway Engineering Society, 2022, 39(7): 12-17.

链接本文:

https://tdgcxb.crec.cn/CN/ 或 https://tdgcxb.crec.cn/CN/Y2022/V39/I7/12

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