[en] By using 2d3v code LCODE the investigations in detail of the reconstruction of a long nonresonant train of relativistic electron bunches into resonant one at plasma wakefield excitation are presented. Because of bunch repetition and plasma frequencies detuning the wakefield beatings are occurred. The bunches in the maximum of beating experience defocusing radial force and go out the interaction with wakefield. It leads to the shortening of the beating period and to the asymmetry between the energy loss of decelerated bunches of the beating front and energy gain of accelerated bunches of the beating rear. In result along with wakefield amplitude beating the monotonic growth takes place with the rate equivalent to the resonant train with smaller current.