AN IDEALIZED FRAMEWORK FOR THE ANALYSIS OF COHESIVE SOILS UNDERGOING DESICCATION

A rational highly idealized framework for the prediction of the spacin g between primary shrinkage cracks in cohesive soils undergoing desicc ation is presented. The proposed framework is based on the theory of l inear elastic fracture mechanics (LEFM), which is used to describe, in a simple manner, the phenomenon of crack propagation. The principle o f effective stresses is used to describe stress partitioning in soils, and a fictitious stress superposition concept is used to predict the average spacing between primary cracks. Crack propagation is analysed with a trapezoidal distribution of total horizontal tensile stress as derived from the material constitutive equations. The model can be app lied to slurries, consolidated natural soils, and compacted clays. An example case of a clay slurry subjected to an evaporation rate of 0.02 cm/h gave a predicted average spacing between primary cracks of about 1.2 m, which agrees with field cracking observations in an Australian coal mine tailings deposit, where the observed average spacing betwee n primary cracks was about 1 m.