Experimental investigation of soil volume changes during freezing and thawing

This thesis explores the thermal-hydro-mechanical behaviour of soils during freezing and thawing, with focus on frost heave and thaw settlement. Ground freezing is a natural phenomenon that affects civil engineering projects, especially in cold regions or where artificial ground freezing (AGF) is employed. Freezing causes water in the soil pores to turn into ice, which expands, leading to ice lens formation and frost heave. Thawing causes the ground to settle, potentially damaging infrastructure. To investigate these challenges, this study employs a new Frost Heave Apparatus (FHA) capable of performing Particle Image Velocimetry (PIV), enabling detailed strain and displacement analysis of frozen soils. A mathematical model for correcting image distortions due to the apparatus geometry was developed. The apparatus tests soils with different kaolin:sand mixtures (0:100, 25:75, 50:50, and 75:25), simulating frost-susceptible and non-frost-susceptible soils under drained and undrained conditions. The experiments focus on observing ice lens formation, frost heave, and settlement under varying freezing rates and load conditions. The findings reveal that non-frost susceptible soils (sand), exhibited no ice lens formation and minimal frost heave but did show settlement during thawing. In contrast, frost-susceptible soils with higher kaolin content developed distinct ice lenses, driving significant frost heave. The position and thickness of these ice lenses were influenced by freezing temperatures and applied loads, with higher loads (up to 400 kPa) reducing frost heave, while lower freezing temperatures (down to -15°C) caused ice lenses to form deeper within the soil. PIV analysis provided full-field strain and void ratio data, revealing a separation void ratio that initiates ice lens formation during freezing. Experiments also demonstrated that freezing rates affect frost heave. A slower freezing rate increased heave by 16.7% under the same boundary conditions. Additionally, soil samples with higher kaolin content (75:25 kaolin:sand) resulted in 29.6% more heave than a 50:50 mixture and 70% more than a 25:75 mixture. The thesis concludes with recommendations for future research, including testing real soils from cold regions and AGF projects, and implementing predictive models for modelling frozen ground behaviour. These efforts will improve the understanding and mitigation of frost heave in engineering applications.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2024

Author dc:creator

• Lattuada, Federico

Advisors dc:contributor.advisor

• Viggiani, Giulia
• Stanier, Sam

• Cryosuction
• Frost heave
• Frost heave apparatus
• Frozen fringe
• Frozen ground
• Ice lens
• PIV
• Thawing

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/cbb8d6d2-c9c3-4915-9211-176a67e36b07/download
• http://purl.org/NET/rdflicense/allrightsreserved

Language dc:language

eng

Author Identifier

0000-0002-3718-1955

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/379808