Deflections and stresses in an ice cover of a frozen channel caused by a load moving with a constant speed along the channel are studied. The channel is of rectangular cross section. The ice cover is isotropic and clamped to the walls of the channel. The fluid in the channel is inviscid and incompressible. The external load is modeled by a localized smooth pressure distribution moving along the central line of the channel. The ice cover is modeled as a viscoelastic plate. Deflection of the ice and strains in the ice plate are independent of time in the coordinate system moving together with the load. The effect of the channel walls on the ice response is studied. This effect can be significant in experiments with loads moving in ice tanks. The linear hydroelastic problem is solved by using the Fourier transform along the channel and the method of normal modes across the channel. It is found that the presence of the vertical walls of the channel reduces the ice deflection but increases the elastic strains in the ice plate. The effects of the load speed, width and depth of the channel on the hydroelastic response of the ice cover are studied in detail. In contrast to the problem of a load moving on ice sheets of infinite extent, there are infinitely many critical speeds of hydroelastic waves in a frozen channel. Correspondingly, there are many values of the speeds of a moving load at which the stresses in the ice cover are amplified. The obtained deflections and strains in the canned ice cover are compared with the corresponding solutions for the infinite ice plate and with the solutions of simplified problems without account for the dynamic component of the liquid pressure. It is shown that the models of ice response without hydrodynamic component of the pressure provide correct stresses in the ice sheet only for very low speeds of the moving load.

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Strains in the ice cover of a frozen channel, which are caused by a body moving under the ice at a constant speed along the channel, are studied. The channel is of rectangular cross section, the fluid in the channel is inviscid and incompressible. The ice cover is modeled by a thin viscoelastic plate clamped to the channel walls. The underwater body is modeled by a three-dimensional dipole. The intensity of the dipole is related to the speed and size of the underwater body. The problem is considered within the linear theory of hydroelasticity. For small deflections of the ice cover the velocity potential of the dipole in the channel is obtained by the method of images without account for ice deflection in the leading order. The problem of a dipole moving in the channel with rigid walls provides the hydrodynamic pressure on the upper boundary of the channel, which corresponds to the ice cover. This pressure distribution does not depend on the deflection of the ice cover in the leading approximation. The deflections of ice and the strains in the ice cover are independent of time in the coordinate system moving together with the dipole. The problem is solved numerically using the Fourier transform along the channel, the method of normal modes across the channel, and the truncation method for resulting infinite systems of linear equations. It was revealed that the strains in the ice strongly depend on the speed of the dipole with respect to the critical speeds of the hydroelastic waves propagating along the frozen channel. The width of the channel matters even it is much larger than the characteristic length of the ice cover.

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The periodic flexural-gravity waves propagating along a frozen channel are investigated. The channel has a rectangular cross section. The fluid in the channel is inviscid, incompressible and covered with ice. The ice is modeled by a thin elastic plate whose thickness varies linearly. Two cases have been considered: the ice thickness varies symmetrically across the channel, being the smallest at the center of the channel and the largest at the channel walls; the ice thickness varies from the smallest value at the one wall to the largest value at another wall. The periodic 2D problem is reduced to the problem of the wave profiles across the channel. The solution of the last problem is obtained by the normal mode method of an elastic beam with linear thickness. The behavior of flexural-gravity waves depending on the inclination parameter of the ice thickness has been studied and the results have been compared with those for a constant-thickness plate. Dispersion relations, profiles of flexural-gravity waves across the channel and distributions of strain in the ice cover have been determined. In the asymmetric case, it is shown that for long waves, the most probable plate failure corresponds to transverse strains at the thin edge of the plate, which can lead to detachment of the ice from the corresponding bank. For short waves, the longitudinal stresses within the plate, localized closer to the thick edge, become maximum. This can lead to cracking of the plate in transverse direction. In the symmetric case, the maximum strains are achieved inside the plate — close to the center, but not necessarily in the midpoint.