Detection and Sizing of Surface Cracks in Expansive Soil Deposits

摘要

The report describes field trials of and subsequent analyses of a method of measuring the depth of shrinkage cracks in expansive clay by using wave propagation techniques. The major reason for wanting to know the depth to which these cracks extend is because this is thought to be closely related to the depth to which a vertical moisture barrier should be carried in order to control moisture influx and efflux from beneath a pavement. A summary review of the wave types is included, considering their generation, propagation, and alteration at a crack, and the feasibility of detection and positive identification of the crack.