In the wake of frequent sinkholes occurring around the globe and recently in Thailand, the Civil Technology Education Faculty of King Mongkut's University of Technology Thonburi is studying the phenomena via simulation and a numerical technique.

Sinkholes are also the subject of an undergraduate thesis by seniors Jakkraphong Sirichairawan and Khatiphong Ornchai, who said the causes were underground erosion and the collapse of soil layers, excessive use of groundwater, and riverside or coastal erosion, which were expanding.

The objective of the thesis is to find out how large sinkholes might affect the shallow foundations of average houses.

Working on a miniature simulation, Khatiphong built a model on a scale of 1:22, with a sinkhole of 2.42 metres in diameter shrinking to 11 centimetres.

He said this simulation found that the sinkholes' depth would not drastically weaken the entire structure, while its width would directly affect the strength of shallow foundations.

In their joint quantitative technique, dubbed the finite element method, which is a mechanism to find approximate solutions to partial differential equations, formulas were generated to mathematically simulate different depths of a sinkhole with a diameter of 2.42 metres and a foundation depth of 1.8 metres.

The diameters varied from 0.5, 1, 2.4 to 3.4 metres with depths increasing 0.5 times each diameter.

This FEM study showed that houses near sinkholes with diameters 0.97 times larger than the shallow foundation of 1.8 metres would collapse.

Asst Prof Thaweechai Kalasin, a lecturer, said the thesis was remarkable in that both students selected their own topic and its content was useful and would serve as a basis for further study in the future.

Source: The Nation/Asia News Network