Effect of drying-wetting condition on attenuation-recovery of soil shear strength of bio-embankment on sloping farmland comprising purple soil

doi:10.11686/cyxb2016298

Abstract

Abstract: During rainfall the soil in bio-embankments undergoes a drying-wetting-re-drying process which may potential influence the shear strength and stability of bio-embankment soil. This study investigated the attenuated recovery of soil shear strength in a mulberry bio-embankment under drying-wetting conditions. The main purpose of the study was to undertake a comprehensive study of mulberry hedge root distribution before and after rainfall (rainfall 0-9 d), the wetting and drying process in bio-embankment soil, physicochemical changes and the influence of roots on soil shear strength. The results show: (1) Roots with root diameter ≤1 mm were concentrated at shallow depths (0-20 cm), while the roots with 2 mm <root diameter≤5 mm were mostly found at 20-40 cm soil depth. (2) There were significant differences (P<0.05) in soil bulk density, soil porosity and soil water of different vertical layers before and after rainfall. In the 30-40 cm soil layer soil bulk density increased after a dry-wet cycle by 5.47%-5.88%, reaching a maximum value 5 days after wetting (1.39, 1.37, 1.44 g/cm³). Soil porosity initially increased and then decreased during a dry-wet cycle. (3) Soil cohesion and internal friction angle responded to an increase in soil water content; initially there was a large decrease in both traits. The correlation between cohesion and soil water content was 0.68, and the correlation between internal friction angle and soil water content was 0.73. (4) Mulberry root diameter classes influenced soil cohesion, internal friction angle and shear strength. Root length density and root surface area density were significantly, positively correlated. Soil cohesion and internal friction angle showed a linear decreasing trend with increasing soil water content. Bio-embankments can improve soil structure, soil aeration, soil nutrient content and reduce soil bulk density, and increase soil porosity, crop growth, development and yield on sloping land.

DING Wen-Bin, HE Wen-Jian, SHI Dong-Mei, JIANG Guang-Yi, JIANG Ping, CHANG Song-Guo. Effect of drying-wetting condition on attenuation-recovery of soil shear strength of bio-embankment on sloping farmland comprising purple soil[J]. Acta Prataculturae Sinica, 2017, 26(6): 56-67.

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