you could drill a hole in your core sample, insert something like a thin water pipeline and increase the water pressure until your specimen fails. Additionally you need to seal the opening of the pipeline. It's like a small borehole packer test.
You could combine this technique with an oedometer or triaxial cell.
Or you could frac a block sample with a cylindrical hole if you are able to take such a specimen.
this publication could be very interesting for the solution of your question:
Wang, H., Xu, W., Jia, C., Cai, M., and Meng, Q. (2016). "Experimental Research on Permeability Evolution with Microcrack Development in Sandstone under Different Fluid Pressures." J. Geotech. Geoenviron. Eng., 10.1061/(ASCE)GT.1943-5606.0001462