Abstract
The focus of this paper was directed towards investigating the influence of multiple freeze–thaw (FT) cycles on the mechanical behaviors of an expansive soil under a wide range of confining stresses (σc) from 0 to 300 kPa. Consolidated undrained (CU) shear tests with pore pressure measurement (σc = 10–300 kPa) and unconfined compression (UC) tests (σc = 0 kPa) were conducted on FT impact specimens to derive the shearing stress–strain relationships and the associated mechanical properties including (i) failure strength (qu), elastic modulus (Eu), effective and apparent cohesion (c′ and c), and effective and apparent friction angle (ϕ′ and ϕ) obtained from CU tests and (ii) qu and reloading modulus (E1%) and stress (Su1%) at 1% strain obtained from UC tests. Besides, the influence of FT cycles on the soil structure was investigated using mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM) tests. Testing results show that FT cycles mainly influence the soil’s macropores with diameters between 5 and 250 μ. Cracks develop during FT cycles and result in slight swelling which contributes to an increase in the global volume of the soil specimens. There is a significant reduction in the investigated mechanical properties after FT cycles. They typically achieve equilibrium after about six cycles. The shearing stress–strain curves transit from strain-softening to strain-hardening as the confining stress increases. A simple empirical model is developed to well describe the strain-softening behavior of the stress–strain curves under low confining stresses.
Highlights
Expansive soils are typically referred to as problematic soils by geotechnical engineers because of their significant swelling and shrinkage characteristics associated with variations in their water content (Li et al 1992; Nelson and Miller 1992; Zou et al 2018)
To track the evolution of the microstructure of specimens upon freeze-thaw cycles, the mercury intrusion porosimetry (MIP) tests and scanning electron microscopy (SEM) tests were performed on untreated specimens and specimens subjected to 1, 4, 6, and 10 FT cycles
2g of mass trimmed from test specimens subjected to different FT cycles were collected for use in MIP and scanning electron microscope (SEM) tests
Summary
Expansive soils are typically referred to as problematic soils by geotechnical engineers because of their significant swelling and shrinkage characteristics associated with variations in their water content (Li et al 1992; Nelson and Miller 1992; Zou et al 2018). The expansive soils in this region are subjected to periodic freeze-thaw (FT) cycles with fluctuations in the ground temperature Due to this reason, there is ice formation and the migration of water in the expansive soils (Edwin and Anthony 1979, Liu et al 2016), resulting in a change in the density and the engineering properties, which include, coefficient of permeability, shear strength and volumetric change (Qi et al 2008; Aldaood et al 2014; 2016; Zhang et al 2015; Liu et al.2017). An empirical model is proposed to describe the strain-softening behavior of expansive soil specimens under low confining pressures that can serve as a useful numerical tool
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
