Construction in expansive soils Geotechnical research at the University of Regina
Dr. Shahid Azam conducts a laboratory test.
The expansive Regina clay is a blessing for the farmers as it can offset the influence of the semi-arid climate prevalent in southern Saskatchewan. This type of soil can store a large amount of water within its pores for a long time, thereby ensuring a healthy crop. However, this same soil is an engineer’s nightmare because it swells and shrinks due to seasonal changes in meteorological conditions. The cyclic movement generates stresses, severely affecting civil infrastructure constructed in and on this soil. Wavy roads, cracked basements, and ruptured pipes are part of the daily lives of Reginians and entail high maintenance costs. The situation is continuously deteriorating because of infrastructure aging and increasing number of extreme weather events. For example, the bursting frequency in the 850-kilometre-long water distribution system has doubled over the last two decades, to 160 breaks per year; the associated annual repair cost is estimated to be $2 million. The University of Regina Geotechnical Research Team, led by Dr. Shahid Azam, an associate professor at the University of Regina, is developing innovative meth104 Saskatchewan Oil Report 2013
Ruptured pipes in Regina, caused by expansive clay that swells and shrinks due to seasonal changes in meteorological conditions.
ods to improve the design of new and existing facilities. With twenty years of experience in expansive soils from different parts of the globe, Azam recently completed a three-year monitoring study on underground water mains in the city. This investigation focused on understanding complex pipe-soil-atmosphere interactions. Thorough instrumentation and extensive data interpretation revealed that the top three-metre layer of soil that houses the buried facilities is the most affected by climatic parameters, and that this layer can heave up to 30 per cent of its original volume. The team is extending this understanding by including the effect of vegetation, deicing salt, and road cover on periodic soil volume changes. “Our work provides a framework for rehabilitating buried pipeline networks in Western Canada, particularly in cities founded on similar soils such as Regina, Winnipeg, and Edmonton,” states Azam. His group is currently developing green technologies by re-using different types of municipal wastes (such as broken glass and tire chips) to reduce the al-
ternate shifting of the local soil. For this purpose, Azam and his team have established the Saskatchewan Advanced Geotechnical Engineering (SAGE) Laboratory. This state-of-the-art facility is sponsored by provincial and federal funds, including those from the Canada Foundation for Innovation, and the University of Regina. Azam mentions that his laboratory is equipped with apparatus that is uniquely suited to undertake the green initiative. Some of these apparatuses include the Large-scale Odometer Test System (LOTS), the centrifuge system, and the physicochemical testing facilities. “Our laboratory testing and fieldmonitoring facilities and methodologies are always designed, fabricated, and calibrated in-house,” Azam says. The next-generation green technologies will be applicable to lightly loaded structures such as pavements, houses, and pipelines. These Regina-based construction methods developed for expansive clays will be useful for most unsaturated soils occurring in arid to semi-arid regions of the globe. For more information, visit uregina.ca. v