Deformation of foundations during freezing of a clay foundation bed

Abstract

The deformation is discussed of the foundations of an unfinished 2-story building, which was caused by the freezing and heaving of the soils in the foundation bed. In the spring, after thawing of the entire stratum of seasonally frozen soils, the unfinished building began to be deformed. Between the concrete blocks of the two foundation walls which were left uncovered during the winter, gaping vertical cracks tapering downward were seen. The concrete base course and foundation blocks were probably laid on previously frozen clay, which by the time of building the foundations had already undergone heaving in the presence of a small surface load. The accumulation of moisture around the sand lens promoted heaving of the clay. Subsequently freezing continued through the concrete blocks and into the warming earth heap, which also proved to be inadequate. The porosity and water content of the clay subjected to heaving was determined. Nonuniform consolidation of the clays led to uneven settlement of the foundations and to cracking. The total displacement of the deformed foundation wall relative to the monolithic part exceeded 2cm. The lost load-bearing capacity of the clays was gradually restored with time, the ground was compressed and compacted and deformations of the structure which were pronounced during the initial period died out.