Granular materials are ubiquitous in nature and important in various applications such as road and railway engineering.Granular materials exhibit complicated mechanical behaviors,which are affected significantly by the irregular shape of particles.Currently,the discrete element method (DEM) has been accepted as an effective approach to investigate the mechanical behaviors of granular materials.However,there are scarce simulations based on DEM in literatures considering the irregularity of particle shape.A new method is proposed to simulate individual real particle with irregular shape using clump constituted by overlapping spheres.First,the geometric model of real particle with surface nodes and inner nodes is established through digitally processing the computerized tomography (CT) scanning data.Second,a clump consisting of spheres is generated to simulate the real particle using a minimum distance criterion.The criterion is implemented by tree optimization algorithm.Influential factors are also introduced to balance the model accuracy and computing cost.Effects of the influential factors,including the density of geometric grid and the minimum distance,on simulations are discussed.Results show that this new method is simpler and more efficient than the previous methods in terms of the model accuracy and computing cost.