The development of perturbations in the circumstellar disks of pre-main-sequence stars caused by clumpy accretion was investigated. Here we perform 3D smoothed particle hydrodynamics simulations of disks perturbed by a recent clump accretion event. These simulations are further explored by radiative transfer calculations to quantify the observational appearance of such disks. It was shown that the density waves in the disks were formed at the fall of the clump. After several revolutions they can transform into spirals and ring structures. Their images in millimeter wavelengths are very similar to those observed with Atacama Large Millimeter/submillimeter Array in some protoplanetary disks. We assume that clumpy accretion may be the source of such structures.