Hydraulic fractures that grow at shallow depth or, more generally, near a free surface, curve towards the surface to become saucer-shaped. These saucer-shaped hydraulic fractures pose challenges for modeling that include the need to track the evolution of the crack path and to follow two distinct moving boundaries corresponding to the leading edge of the crack and the fluid front. Results from a coupled, implicit time stepping numerical model agree well with detailed laboratory experimental data for fluid-driven cracks in glass and PMMA. Specifically, the model and laboratory results show good agreement for the crack path, the evolution of the fluid and fracture fronts, the crack opening, and the injection fluid pressure. This strong comparison not only demonstrates the viability of the numerical model, but more generally the results demonstrate that considering coupling among fluid flow, elastic deformation, and radially symmetric crack growth captures enough of the relevant physical processes to accurately predict the leading order behavior of the physical system realized in the laboratory using homogeneous brittle-elastic solids.
Bibliographical noteFunding Information:
Funding for the experiments was provided by the Australia Coal Association Research Programme (ACARP) , Project C10010 with additional support from CSIRO. Funding for the modeling was provided by The National Science Foundation under Grant No. 0600058 . Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. These sources of support are gratefully acknowledged.
- Displacement discontinuity method
- Elastic fracture mechanics
- Experimental crack mechanics
- Hydraulic fracturing
- Numerical modeling