Physical model test of seepage and deformation characteristics of shallow expansive soil slope
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ORIGINAL PAPER
Physical model test of seepage and deformation characteristics of shallow expansive soil slope Zhangjun Dai 1
&
Shanxiong Chen 2 & Jian Li 1
Received: 11 November 2019 / Accepted: 17 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Large-scale physical model test on expansive soil slope at a shallow depth is conducted with the aim of monitoring moisture content and swelling deformation. In this paper, a wedge-shaped model box with a bevel at the bottom was developed to reflect the actual channel slope in the South-to-North Water Transfer Project. The results provide an improved understanding of the physical behavior and failure mode of a saturated-unsaturated expansive soil slope subjected to moisture content variation. Showing that, after rainfall, the surface soil quickly became saturated, with the deeper soil moisture remaining unchanged. Infiltration depth, speed, and saturation region reduced with the increasing height along the slope. Surface displacement increased from slope foot to slope shoulder, and significantly attenuated towards the depth. Horizontal displacement was about 1/3–1/2 of the vertical displacement. The larger the increment of the soil moisture, the greater the surface deformation. Soil showed dehydration shrinkage with fissures first appearing in the soil surface and expands downward with continuing evaporation. The junction of saturated-unsaturated zone and the wet-dry interface were the areas of stress concentration. Swelling effect led to stress field redistribution in the expansive soil slope, and it was the most important factor causing expansive soil shallow slope failure. Keywords Expansive soil . Shallow depth . Slope . Physical model test . Swelling deformation
Introduction Expansive soil slope instability and landslide are seasonal, and environmental factor is one of the main effects (Dhowian 1981; Ruwaih 1984; Houston et al. 2011; Dafalla and Shamrani 2012). Slope instability, embankment slump, and channel landslides caused by climate change are widespread (Liao 1984; Ai-Homoud et al. 1996; Liu 1997; Shi et al. 2002; Meisina 2004; Xeidakis et al. 2004). The mid-route of the South-to-North Water Transfer Project has a total length of over 1472 km, among which expansive soil area will cover about 340 km (Fig. 1). * Zhangjun Dai [email protected] 1
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
2
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
Expansive soils are mainly Middle Pleistocene alluvial and flood sedimentary clay, Lower Pleistocene flood sedimentary clay, and Neogene hard clay. Strong expansive soil is mainly distributed in the Xingtai-Handan area and Nanyang Basin. Nanyang area is in the transition zone from subtropical to warm temperate zone. It is a typical monsoon humid climate with four distinct season
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