6Hoek E, Brown E T. Practical estimates of rock mass strength[ J]. Int J Rock Mech Min Sci, 1997, 34(8) : 1165 - 1186.
7CAI M, KAISER P K, UNO H, et al. Estimation of rock mass de- formation modulus and strength of jointed hard rock masses usingtheGSI system[J]. Int J Rock Mech Min Sci, 2004, 41(1): 3 -19.