Damage characteristics and mechanisms of soil structures under salt weathering
Received date: 2024-03-06
Revised date: 2024-05-09
Online published: 2025-01-02
This study investigates the damage characteristics of loess structures and the deterioration of loess strength under the influence of salt weathering, with a focus on unidirectional dehumidification conditions. The findings provide valuable references for soil and water conservation, as well as disaster prevention strategies in the Loess Plateau. Q2 loess from Fugu County, Shaanxi Province, China was selected for macro- and micro-scale observations and shear strength tests under varying sodium sulfate contents. The results indicate the following: (1) Macroscopic effects: An increase in salt content significantly impacts the apparent damage degree and expansion displacement of the samples. Samples with salt contents ranging from 1.0% to 2.5% exhibited contour scaling damage characteristics, transitioning from uneven surface crusts to extensive salt spots and expansion cracks. In contrast, samples with a lower salt content of 0.5% did not show salt swelling, salt spots, or crust formation. The salt weathering process progresses through three stages: germination, growth, and stability. (2) Microscopic effects: Salt weathering leads to the formation of agglomerates and expansive pores within loess. Sodium sulfate decahydrate crystals were observed as a direct result of the salt weathering process. (3) Shear characteristics: The shear behavior of the samples transitioned from strain softening to strain hardening after salt weathering, with significant degradation in peak strength and reduced cohesion. As sodium sulfate content increased, salt weathering intensified the effects of “salt crystallization-induced expansion” and “soil drying-induced coagulation” in loess. This process generated numerous expansion cracks and pores both on the surface and within the loess, ultimately causing severe structural and strength deterioration.
Key words: loess; sodium sulfate; salt weathering; shear strength; damage
DUAN Zhao , LI Ruiyi , SONG Kun , YAN Xusheng , ZHENG Licai , HE Ziguang . Damage characteristics and mechanisms of soil structures under salt weathering[J]. Arid Land Geography, 2024 , 47(12) : 2041 -2050 . DOI: 10.12118/j.issn.1000-6060.2024.152
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