Performance of Irrigation Systems for Control of Moisture Changes

Abstract

Over the last 30 yr, Eastern Canada has experienced several droughts during which extensive settlement problems developed in lightweight buildings founded on the Champlain Sea clays. These clays are known for their open structure, which collapses when the moisture content is decreased and does not return to its initial state if water is added to the soil. This type of situation occurs during droughts in which the lack of rainfall causes the desiccation of clays. If trees are located in close proximity to buildings founded on shallow footings, the problem is exacerbated, since the roots can grow beneath the foundations and extract moisture during droughts. This will cause the clays to shrink and the structures to settle. The goal in dealing with these clays is to try to maintain a constant soil moisture. The elimination of planter areas around the perimeter of the buildings can help reduce moisture changes. This paper presents the results of a field monitoring program, on the effectiveness of different irrigation systems, in maintaining a constant soil moisture and in reducing building settlements in the clay deposits of Montreal Island.