Abstract: To investigate the creep characteristics of fractured rock mass in coal measure strata under anchorage, uniaxial creep tests were carried out on anchored, unanchored fractured and intact specimens at different fracture dip angles (15°, 30°, 45°, 60°, 90°). The results show that the instantaneous strain of the unanchored fractured specimens is greater than that of the intact specimens under the same stress loading level. The difference between the anchored fractured specimens and the intact specimens gradually decreases as fracture inclination increases. With the increase of stress loading level, the steady-state creep variable of each rock specimen also increases. The steady-state creep rate of fractured specimens initially decreases and then increases with the increase of fracture dip angle. However, the steady-state creep rate of anchored fractured specimens is lower than that of unanchored fractured specimens under the same stress level. Significant differences in crack penetration development exist between unanchored and anchored fractured specimens at low fracture dip angle. Based on the CVISC creep model, parameter inversion was performed, and the trends of Maxwell and Kelvin correlation coefficients with stress loading level were obtained. The stress-strain isochronous curve method and the unsteady rheological discriminant method were employed to study the long-term strength variation of fractured specimens. The research results provide an experimental basis for long-term stability analysis and bolt support schemes of coal mine roadway.

Key words: coal mine, fracture, bolts, creep, long-term strength, CVISC creep model