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Open AccessArticle

Using Post-Harvest Waste to Improve Shearing Behaviour of Loess and Its Validation by Multiscale Direct Shear Tests

by Wen-Chieh Cheng 1,2,*, Zhong-Fei Xue 1,2, Lin Wang 1,2 and Jian Xu 1,2
1
School of Civil Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China
2
Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering (XAUAT), Xi’an 710055, China
*
Author to whom correspondence should be addressed.
Appl. Sci. 2019, 9(23), 5206; https://doi.org/10.3390/app9235206
Received: 19 October 2019 / Revised: 25 November 2019 / Accepted: 27 November 2019 / Published: 29 November 2019
(This article belongs to the Special Issue Soil Erosion: Dust Control and Sand Stabilization)
Loess and PHW (post-harvest waste) are easily accessible in the Chinese Loess Plateau and have been widely applied to construction of residential houses that have been inhabited for decades under the effect of freeze-thaw cycles. Although many researchers have recognised that the addition of fibers to loess soil is effective in preventing soil erosion and stabilising slopes, a consensus on this claim has not been reached yet. This study investigates the shearing behaviour of the loess-PHW mixture using small-scale and large-scale direct shear (SSDS and LSDS) tests. Four typical shear stress versus horizontal displacement curves from the multiscale direct shear tests are recognised where one is featured with strain-softening shape and the other three with a strain-hardening shape. Two out of the three curves with strain-hardening shape show a gradual increase in the shear stress at additional and larger displacements, respectively, in which some factor starts to have an influence on the shearing behaviour. Comparisons of the shear strength measured in SSDS and LSDS are made, indicating that there are differences between SSDS and LSDS. The effect of PHW addition on shear strength is assessed in order to determine the optimal dosage. The improvement of shear strength is attributed to the effect of particle inter-locking, resulting from the addition of PHW to loess specimens, and takes effect as the water content surpassed a threshold, i.e., >14%, that facilitates particle rearrangement. Particle-box interaction behaviour is assessed at the same time, and the findings satisfactorily address the main cause of the gradual increase in shear stress following the curve inflection point. The improved shearing behaviour proves the ability of the loess-PHW mixture to resist the seepage force and consequently stratum erosion. View Full-Text
Keywords: direct shear test; post-harvest waste; Chinese Loess Plateau; optimal dosage direct shear test; post-harvest waste; Chinese Loess Plateau; optimal dosage
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Cheng, W.-C.; Xue, Z.-F.; Wang, L.; Xu, J. Using Post-Harvest Waste to Improve Shearing Behaviour of Loess and Its Validation by Multiscale Direct Shear Tests. Appl. Sci. 2019, 9, 5206.

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