ABSTRACT
This study addresses the question of sinkhole stability in Paleozoic carbonate rocks where the bedrock is dense, stable, with solution cavities that can be considered a fixed background on a time scale of hundreds to thousands of years. Active sinkhole processes then involve only the transport of unconsolidated soils and alluvial stream sediments. The transport process has two components: a gravity and storm in wash driven vertical component of soil piped downward through solutionally widened fractures and shafts in the bedrock and a stream flow-driven horizontal component that moves the piped-in soil and a load of alluvial stream sediment toward some ultimate discharge to the surface drainage system. Both of these components have thresholds which must be exceeded for sediment to move. The threshold for vertical transport is related to bedrock fracture aperture, cohesive strength of soils, soil moisture, and particle size distribution. The threshold for lateral transport can be analyzed in terms of a threshold energy for sediment movement which in turn is a function of maximum flow velocities and sediment particle size. Storm water surges are the most important factor in the lateral transport system. If it can be demonstrated, for a particular site, that sediment transport factors remain below the critical thresholds, then the site should be stable against further sinkhole activity.
