We performed numerical simulations that modeled experiments in the previous paper (I) on a small-scale explosion inside an underground magazine both with and without a protective dike near the exit. The internal length-to-diameter ratio of the magazine was 3. To understand the effects of the dike on the azimuthal characteristics of the blast wave from the exit, the flow fields were visualized and the peak overpressure of the blast wave was measured. The azimuthal characteristics in the present simulations and the experiments showed good agreement. The dike prevented the detonation products from expanding along the exit direction and mitigates the peak overpressure near the dike. Incrementing the azimuth angle reduced the peak overpressure. The blast wave reflected off the dike, resulting in an enhanced blast wave behind the underground magazine. Our study showed that the iso-pressure circle in the case of a surface explosion would be converted into an iso-pressure ellipse in the case of an explosion from the underground magazine.