Four kinds of backfill with cement-tailing ratio of 0.250

0.125

0.100 and 0.083 respectively were tested; and their stress-strain curves were obtained. Analyzing the deformation and failure characters of different backfills

their damage constitutive equations investigated with damage mechanics whose calculating results coincide with experiment results well were proposed. The results of damage analysis show that there have different damage characters in different backfills

e. g. the lower the cement-tailing ratio the lower the damage value when stress reaches to peak value; the lower the content of cement the more rapid in damage and the more abrupt in failure process after peak value of stress. According to the principle that releasing energy from excavated rock mass corresponds with cumulative energy of deformation in backfill; the reasonable matches between backfill and rock mass whose coefficient correlates with earth stress

elastic modulus of rock mass

elastic modulus of backfill and damage parameters of backfill respectively were researched. In order to apply it to engineering conveniently

regressing the experimental results of backfill

a design formula of strength for cemented backfill was put forward; and the required strengths of backfill in deep deposit were researched.