Numerical analysis of multiple hydro-fracture growth in layered media based on a non-differentiable energy minimization approach

•A non-differentiable energy-based formulation is extended for multiple hydraulic fracturing in layered media.•The graph theory is applied to identify the interconnected network of pressurized cracks in heavily fractured rock mass.•Several numerical simulation results are presented for multiple hydro-fracture growth in layered media for a range of contrasts in material stiffness.