Model experiments were conducted to research the effect of liquefaction on breakwaters built on silty soils. The pore pressures in the silty soil under the breakwater were measured by pore pressure transducers during the exposure of the model to regular waves used as cyclic loading. In this research, some methods to prevent liquefaction were also used to observe the effect of them on the change in pore water pressures. Three experiments were conducted and in the first one, no improvement to the soil was undertaken; in the second experiment, six stone columns, which were placed between the failure arc and the toe of the breakwater, were used to increase drainage. The third experiment was conducted with a geotextile, which was placed between the failure arc and the toe of the breakwater. The geotextile has increased the resistance time of the soil to liquefaction at the toe of the breakwater.