Effects of Intergranular Strains of Hypoplasticity Models on Sinkhole-Induced Ground Deformations

This paper studies the influence of considering small strain behavior on the computation of ground deformations arising from subsurface cavities in sinkhole-prone areas. Sinkholes occur frequently in karst terrain and cause human casualties and major infrastructure damage in karst environments. The testing bed of this study is the analysis of geotechnical failure mechanisms associated with the Winter Park sinkhole; known as Florida’s most devastating sinkhole and one of the largest documented sinkholes in the United States. In this paper, hypoplasticity models for sands and clays are used to model the behavior of silty sands and overconsolidated clays that represent the predominant subsurface soils encountered at the site. Field measurements and published correlations are used for the determination of constitutive soil parameters used in the numerical simulations. PLAXIS 2D is the finite element platform used to capture the geotechnical mechanisms of sinkhole failure. Ground deformations, shear, and volumetric strains arising from the expansion of an underground deep cavity are computed considering the intergranular strain concept in the numerical simulations and are compared against the results obtained using basic hypoplasticity models, which ignores the small strain behavior of soils. It is concluded that by including the small strain soil behavior via the intergranular strain concept, a more realistic representation of sinkhole-induced geotechnical response is provided in terms of maximum ground surface settlements, distortions, and sinkhole influence zones than the corresponding simulations conducted using basic hypoplasticity models.