Sinkholes: Trigger, Development, and Subsidence—A Review

Sinkholes are surface depressions which can often be catastrophic because of collapse of large underground openings or voids created due to natural or anthropogenic activities. Previously, the term “sinkhole” was used to indicate any surface collapse which occurs due to the presence of karstic strata, containing cavities due to the dissolution of carbonate rocks, but now it has become a generalized term to represent ground subsidence regardless of the origin. Sinkholes can occur due to either underground mining or tunnelling activities or pipeline failures. This paper provides an insight to the mechanism which occurs in the ground due to sinkholes in karstic but also in non-karstic grounds. It reviews the available research evidence in detail. The classification of sinkholes based on the factors which trigger the cavity formation and the mechanism which leads to the collapse is first discussed. This study shows that damaged pipes are the major source behind sinkholes, many incidences of which are observed in urban areas of this country. The rate of cavity development and geometry of sinkhole are found to be governed by the origin, thickness, and properties of the overburden soil, and the rate of suffosion. The paper further reviews the physical and analogical models which have been developed to predict the size of this problem, and the stains in the soil, which lead to the collapse. This is followed by the review of the advanced investigation techniques using field surveys.