A direct numerical simulation (DNS) technique based on the pressure correction-volume of fluid method is developed to simulate the two-phase granular flow impact on a tall structure. The numerical method includes a direct-forcing immersed boundary (IB) method to track the particle motions, a discrete element method (DEM) to compute the forces of particle-particle and particle-wall collision, and the partial volume-of-fluid (PVOF) method to solve the two-phase flow. The granular flow impact on a structure consists of a three-dimensional submerged sphere stack in a water dam. After the dam breaks, the submerged sphere stack impacts on a tall structure. To verify the efficiency and capability of the present method, three test cases, a three-dimensional dam-break problem, the emergence of a submerged circular cylinder, and the DEM model validation, are performed. The water front in the dam-break problem is computed and compared well with the experimental data. Then three-dimensional wave impact on a tall structure and the three-dimensional collapse of a submerged sphere stack impact on a tall structure are investigated. (C) 2012 Elsevier Ltd. All rights reserved.