INFLUENCE OF SUBSURFACE FRACTURES ON SURFACE DEFORMATION OF AN ELASTIC HALF-SPACE

The paper presents a solution for calculation of the surface uplift fi eld of a semi-infinite elastic solid embedded with a pressurized ellip tical crack oriented at any angle, and at any depth. The results prese nted are those for a uniform pressure loading on the crack face, simul ating a static pressurized hydraulic fracture, but the mathematical te chnique developed can be extended directly to non-uniform normal loads or general shear loads in the form of a polynomial up to the third or der. The result of a special case of the new solution, where the crack is penny shaped and parallel to the free surface, is compared with re sults from Sun's solution and from experiments which were designed and performed by the authors. The experiments involved pressurization of a penny-shaped crack in a polyurethane material which is linear elasti c under low stresses, and measurement of surface deformation by hologr aphic interferometry and Fizeau interferometry. The correspondence bet ween theory and experiment is excellent.