Three-dimensional sinkhole stability of spherical cavity

Sinkhole occurrences due to underground water mains operations have piqued people's curiosity. Most research works were in relation to geophysical practices to discover the subsurface cavity. Very few works can be found in relation to the investigation of soil stability due to underground cavity shapes. The actual shape of an underground cavity and its transformation is difficult to predict, though the sinkhole failures are mostly circular in shape on the ground surface. This study explores the three-dimensional collapse stability of three distinct idealized cavity geometries, namely the circular, semi-spherical, and spherical cavities. For an active failure, dimensionless parameters are used to investigate the combined impacts of soil cover, surcharge pressure, soil weight, and internal pressure using advanced finite element limit analysis. Numerical results are compared with the two-dimensional axisymmetric results, and design charts presented to cover a wide range of design parameters for practical applications.