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谌文武, 贾博博, 蔡韬, 陈浩鑫, 李湘. 融雪与降雨入渗下含盐土遗址的冻融劣化研究[J]. 岩土工程学报, 2022, 44(2): 334-342. DOI: 10.11779/CJGE202202015
引用本文: 谌文武, 贾博博, 蔡韬, 陈浩鑫, 李湘. 融雪与降雨入渗下含盐土遗址的冻融劣化研究[J]. 岩土工程学报, 2022, 44(2): 334-342. DOI: 10.11779/CJGE202202015
CHEN Wen-wu, JIA Bo-bo, CAI Tao, CHEN Hao-xin, LI Xiang. Freeze-thaw deterioration of saline earthen sites under snowmelt or rainfall infiltration[J]. Chinese Journal of Geotechnical Engineering, 2022, 44(2): 334-342. DOI: 10.11779/CJGE202202015
Citation: CHEN Wen-wu, JIA Bo-bo, CAI Tao, CHEN Hao-xin, LI Xiang. Freeze-thaw deterioration of saline earthen sites under snowmelt or rainfall infiltration[J]. Chinese Journal of Geotechnical Engineering, 2022, 44(2): 334-342. DOI: 10.11779/CJGE202202015

融雪与降雨入渗下含盐土遗址的冻融劣化研究

Freeze-thaw deterioration of saline earthen sites under snowmelt or rainfall infiltration

  • 摘要: 采用含水率、电导率、弹性波速及无侧限抗压强度等指标,结合试样表观及微结构变化研究了含盐土遗址在融雪或降雨入渗的初始条件下经历冻融循环的劣化机制。结果表明:在冻融循环过程中,试样含水率因融雪与降雨入渗的水分补给及蒸发散失而先增加后减小并趋于稳定,盐分随水分迁移后分别在试样高度5,3.5 cm处富集;水分入渗增加了土粒间的水膜厚度,试样弹性波速和无侧限抗压强度显著下降;随着冻融循环的进行,水分蒸发散失,试样波速和强度逐渐回升,盐分和降水形式是影响试样强度恢复的关键因素。当Na2SO4含量大于0.4%时,其含量的增加会降低试样强度恢复比,NaCl的加入提高了试样强度恢复比,但降低了强度回升速度。经历12次冻融循环后,融雪入渗使易溶盐充分弥散而有助于土体强度恢复,顶部水盐富集导致试样顶面形成酥碱和翻卷的泥皮;降雨入渗使试样微裂隙发育且大孔隙(> 16 μm)占比增大,湿润锋处水盐富集导致试样侧面出现横向裂缝,试样强度回升速度和幅度均较小。

     

    Abstract: The changes of samples after freeze-thaw cycles under the initial conditions of snowmelt or rainfall infiltration are characterized considering the water content, conductivity, elastic wave velocity and unconfined compressive strength. Furthermore, the freeze-thaw deterioration mechanism of the saline earthen sites is studied based on the macroscopic and microstructure changes of the samples. The results show that during the freeze-thaw cycles, the water content of the samples increases first, then decreases and tends to be stable due to the water supply and evaporation loss of snowmelt and rainfall infiltration, and after migration with water, the salt is enriched at the height of 5 and 3.5 cm, respectively. The supplied water increases the thickness of bound water film between soil particles, and the elastic wave velocity and unconfined compressive strength of the samples decrease significantly. With the progress of freeze-thaw cycles, the water evaporates, and the wave velocity and strength of the samples increase gradually. The salt content and precipitation form are the key factors affecting the strength recovery of the samples. When its content is more than 0.4%, the increase of the content of Na2SO4 will reduce the strength recovery ratio of the samples. The addition of NaCl improves the strength recovery ratio of the samples, but slows down the strength recovery rate. After 12 freeze-thaw cycles, the snowmelt infiltration makes the soluble salt fully disperse in the samples, which is conducive to the recovery of soil, the accumulation of water and salt at the top of the samples leads to the formation of salt efflorescence and rolled mud. The rainfall infiltration makes microcracks develop and the proportion of macropores (> 16 μm) increase, the accumulation of water and salt at the wetting front leads to transverse cracks at the side of the samples, and the strength recovery speed and amplitude of the samples are small.

     

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