Numerical investigation of sinkhole stability in undrained clay

Numerical investigation of sinkhole stability in undrained clay

The stability of the soil that overlies a cavity is often of concern when it comes to the risk of sinkhole occurrence. Current sinkhole studies have been centred on the use of geophysical techniques to detect underground cavity sizes and associated depths. With measured information, it is possible to theoretically predict the extent of ground surface collapse.

The aim of the research is to numerically study the soil stability and its associated ground surface failure extent of an undrained cohesive cover over a collapsible sinkhole. The shear strength reduction method is utilised to explore two- and three dimensional failure mechanisms of a trapdoor by using the finite difference programs. The problem solution is formulated by using two popular methods in geotechnical engineering i.e. Taylor’s stability chart method and Broms and Bennerrmark’s stability number. Stability results are compared with those using finite element limit analysis and other published literatures. Several practical examples are provided to demonstrate the use of design charts and tables.

Current study of soil arching development and ground surface failure extent in three-dimensional spaces provide useful engineering information, which may assist in decision making by practical engineers. Together with the use of geophysical tools, an early warning system shall be developed in the future to save lives and prevent billions in property losses.