To sufficiently seal an underground facility in fractured rock, it is necessary to obtain adequate grout spread into the surrounding fractures. The grout spread itself depends on parameters, the most significant of which are the grout filtration tendency and rheological properties. These properties can be affected by the applied pressure. Use of high-frequency oscillating pressure is a method that has been shown to improve grout spread by virtue of reducing the grout apparent viscosity. However, this method has not yet been industrialized due to limited efficiency and rapid attenuation of the oscillation along a fracture. To address these issues, we present a pilot investigation to show the potential of high-frequency oscillation applied to the host rock to improve grout spread in fractures. The proposed method is examined using an artificial fracture, the so-called Varying Aperture Long Slot (VALS) that has been recently developed. The results are compared between the two cases with and without vibration. The study shows the potential of the method on improving the grout spread in rock fractures.