Some possible interconnections between shrinkage cracking and gilgai

Abstract

There is the specific form of a microrelief of swelling clay soils, called gilgai. The relief consists of mounds, depressions, and even sections of the surface. Existing models of the phenomenon do not account for the role of horizontal shrinkage cracks and are qualitative. The objective of this work is to propose a quantitative model of possible interconnections between the formation of shrinkage cracks, vertical and horizontal, and the gilgai microrelief. First, a summary is given of available models of the vertical and horizontal shrinkage cracks in soils. A proposed mechanism of the gilgai formation is based on a width increase of the air-filled horizontal cracks during a wetting season. Some simple relations are considered between the gilgai microrelief and vertical and horizontal shrinkage cracking. The analysis results of available data on geometrical gilgai characteristics favour the feasibility of the model.