Preparation and strength model of rock-like specimens containing randomly distributed fractures based on PVA water-soluble material

Quantifying rock strength with randomly distributed fractures is essential for preventing and controlling disasters in underground engineering. This study investigates the incorporation of polyvinyl alcohol (PVA) water-soluble materials in the preparation of rock specimens. The evolution of rock compressive strength in specimens featuring randomly distributed fractures prepared with PVA materials is analyzed, taking into account the influence of confining pressure. Ultimately, a strength model for fractured rock is established by accurately quantifying the damage effects of individual fractures and characterizing the statistical properties of distributed fractures, with its reliability subsequently verified. The results indicate that: (1) Rock specimens with randomly distributed fractures are prepared by mixing PVA water-soluble materials with cement mortar, pouring the mixture, and subjecting the cured specimens to a warm bath treatment. (2) Rock strength exhibits a positive linear relationship with confining pressure and a negative linear relationship with total fracture area. While maintaining a constant total fracture area, rock strength demonstrates a positive linear correlation with the number of fractures. (3) The theoretical strength model successfully reproduces the experimental strength, demonstrating that the established model effectively characterizes the evolution of rock strength under the combined effects of confining pressure and fracture distribution parameters. (4) The sensitivity of rock strength to confining pressure is negatively correlated with total fracture area, while its sensitivity to changes in total fracture area shows a positive correlation with confining pressure.