Water-induced changes in mechanical response and fragmentation behavior of rocks exposed to conical pick indentation: Implications for rock cuttability improvement

Water-weakening presents a promising strategy for the in-situ improvement of rock cuttability. This study unveils the influences of water saturation on the mechanical response and fragmentation characteristics of rock samples. A series of rock-cutting tests using conical pick indentation was conducted on three types of sandstone samples under both dry and water-saturated conditions. The relationships between cutting force and indentation depth, as well as typical cuttability indices are determined and compared for dry and water-saturated samples. The experimental results reveal that the presence of water facilitates shearing failure in rock samples, as well as alleviates the fluctuations in the cutting force-indentation depth curve Furthermore, the peak cutting force ( F p ), cutting work ( W p ), and specific energy (SE) undergo apparent decrease after water saturation, whereas the trend in the indentation depth at rock failure ( D f ) varies across different rock types. Additionally, the water-induced percentage reductions in F p and SE correlate positively with the quartz and swelling clay content within the rocks, suggesting that the cuttability improvement due to water saturation is attributed to the combined effects of stress corrosion and frictional reduction. These findings carry significant implications for improving rock cuttability in mechanized excavation of hard rock formations. • The influences of water saturation on the cuttability of three rocks are evaluated. • The energy partition in rock cutting test using a conical pick is discussed. • The mineral-controlled mechanisms for water enhancing rock cuttability is interpreted. • Conception and method for in-situ precise improvement of rock cuttability in mechanized excavation are proposed.