We study experimentally collapse processes of granular heaps due to moving retaining walls of containers. We focus on trajectories of flows of granular matter during the collapse process with various initial heights (Ho) and widths (Xo) whose aspect ratios (Ho / Xo) are the same value, Ho / Xo = 2.0. It is observed that the heaps show increase of volume which is so called 'dilatancy' at an early stage of collapse and the trajectories of all particles in flowing region exhibit logarithmic curves. The latter yields a scaling law for the trajectories of the granular matter.