| 徐伟皓,陈波.两种非饱和原状土的持水曲线及孔径分布[J].安徽建筑大学学报,2023,31(): |
| 两种非饱和原状土的持水曲线及孔径分布 |
| The Water Retention Curves and Pore Size Distributions ofTwo Unsaturated Natural Soils |
| 投稿时间：2022-09-14 修订日期：2022-10-18 |
| DOI： |
| 中文关键词: 非饱和土 持水特性 全吸力范围 孔径分布 持水曲线预测 |
| 英文关键词: unsaturated soil water retention behaviors over a wide suction range pore size distribution prediction of water retention curves |
| 基金项目:浙江省自然科学基金(LZY21D020001)；浙江省交通运输厅科技计划项目(2021044) |
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| 中文摘要: |
| 分别用轴平移技术和蒸汽平衡技术对原状黄土和红土施加低吸力(s≤1.5MPa)和高吸力(s≥3.29 MPa),量测土体在各级吸力下的含水率和孔隙比,得到两种土体在广吸力范围内的持水曲线,获取土体的持水曲线基本参数(进气值、残余吸力值和过渡段曲线斜率)。开展土体孔径分布测定试验,揭示两种土体的持水特性存在差异的微观机理。最后,基于土体脱湿过程与汞压入过程基本一致的特性,利用孔径分布曲线对土体的持水曲线进行预测,并与试验得到的持水曲线进行对比。研究结果表明： ① 黄土持水曲线具有2个进气值、1个残余吸力值,过渡段为3段不同斜率的直线所构成的双峰型持水曲线。红土持水曲线则具有1个进气值和残余吸力值,过渡段为单一斜率线段构成的单峰型持水曲线 ② 黄土的孔径分布曲线则双峰孔径结构,且大孔径集中分布的峰值大于小孔径集中分布的峰值。红土的孔径分布曲线为单峰孔径结构,且在设备可探测的孔径范围内均有一定量的分布③ 利用孔径分布曲线预测的含水率与吸力关系与实测结果基本吻合,表明孔径分布曲线可有效预测土体的持水特性。但是,由于预测时未考虑土体实际干化过程中的孔隙比减小,导致相同吸力下的预测饱和度小于实测饱和度。 |
| 英文摘要: |
| The axial translation technique (ATT) and vapor equilibrium technique (VET) were combined to applied the low suctions (s≤1.5MPa) and high suctions (s≥3.29 MPa) on the undisturbed loess and lateritic clay. The water retention curves over a wide suction range were obtained, and the basic parameters (air- entry value, residual suction, slope at transition zone) of the water retention curve were determined, by measuring the gravimetric water contents and volumes of different specimens under specified suctions. Moreover, the pore size distributions (PSDs) of specimens were obtained from mercury intrusion porosimetry (MIP), to investigate the effect of microstructure on the water retention behaviors of soils. Lastly, the predicted water retention curves from PSDs, attributing to the fact that the mercury intrusion into a porous medium is a similar process to air injection into a saturated soil, were compared to the measured water retention curves. The results show that: (1) two air-entry values and one residual suction, with three different gradient lines existing in the transition zone in the bimodal water retention curve of loess. On the contrary, only one air-entry value and residual suction, with one gradient line existing in the transition zone in the unimodal water retention curve of lateritic clay. (2) the PSDs of natural loess is bimodal, and the peak of macro-pores is higher than that of micro-pores in the dominant pore size distributions. However, the PSDs is unimodal for the lateritic clay with the pore distributed in the entire diameter range that can be detected by the MIP. (3) the consistencies of predicted and measured gravimetric water content versus suction demonstrate that the PSDs can well be adopted to predict the water retention curves of soils. However, the predicted saturation degree is lower than the measured saturation degree under the same suction, due to unconsidering the reduction of void ratio during the drying. |
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