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首页> 外文期刊>Arabian Journal for Science and Engineering >NMR-Based Study on Soil Pore Structures Affected by Drying–Wetting Cycles
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NMR-Based Study on Soil Pore Structures Affected by Drying–Wetting Cycles

机译：基于核磁共振的干湿循环影响的土壤孔隙结构研究

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Experimental tests are conducted to investigate pore structure variations during the swelling process of expansive soils thatexperienced 0–4 drying–wetting cycles. The mathematical connection between the swelling deformations and pore structuresis analyzed by nuclear magnetic resonance. The experimental results show that the specimens subjected to 1–4 cycles showhigher swelling rates. Swelling curves are divided into rapid swelling, slow swelling and slowly stable stages, and threestraight lines are appropriate to fit these curves. Based on a defined T_2 cutoff (T2C 1.84 ms) for the relaxation time, thepores in the test specimens are divided into micropores (r<1.28 nm) and macropores (r ≥1.28 nm). With a lower watercontent (ω <19.0%), the proportions of these two pore types are close to each other. When the water content exceeds 19.0%,a significantly large proportion of the macropores that is the main factor which causes swelling deformation in the wettingprocess of soil is observed. Drying–wetting cycles expand the spaces among the soil particles, and the cycle number showsa linear relationship with the macropores, while it exerts less influence on the micropores. If the soil is subjected to multipledrying–wetting cycles, the ability of the soil to prevent erosion is weakened since the water in the macropores is more readilylost.
机译：进行了实验测试，以研究经历0–4次干湿循环的膨胀土壤在膨胀过程中的孔结构变化。通过核磁共振分析了膨胀变形和孔结构之间的数学联系。实验结果表明，经过1-4次循环的试样显示出更高的溶胀率。溶胀曲线分为快速溶胀，缓慢溶胀和缓慢稳定阶段，并且三条直线适合于这些曲线。根据松弛时间的定义的T_2截止（T2C 1.84 ms），将试样中的孔分为微孔（r <1.28 nm）和大孔（r≥1.28nm）。含水量较低（ω<19.0％）时，这两种孔类型的比例彼此接近。当水含量超过19.0％时，观察到很大比例的大孔是引起土壤润湿过程中溶胀变形的主要因素。干湿循环扩大了土壤颗粒之间的空间，循环数与大孔呈线性关系，而对微孔的影响较小。如果土壤经过多次干湿循环，则土壤防侵蚀的能力就会减弱，因为大孔中的水更容易流失。

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