Abstract: Dynamic triaxial tests were carried out on three groups of desulphurized gypsum samples with compactness of 0.85, 0.90, and 0.95 to examine the dynamic modulus and damping ratio of desulphurized gypsum with varied compactness. The test was divided into two parts: isotropic consolidation test and anisotropic consolidation test, of which the former was conducted at consolidation stress ratio 1 under confining pressure as of 100 kPa, 200 kPa, and 400 kPa, respectively, and the latter at consolidation stress ratio 1, 1.5, and 2 under confining pressure as of 100 kPa. Test results evinced that with the increase of degree of compaction, the dynamic modulus of desulphurized gypsum augmented gradually; damping ratio changed inapparently when dynamic strain was less than 10^-5, and gradually reduced when dynamic strain exceeded 10^-5.The initial dynamic modulus displayed a good power correlation with compaction degree. The formula of initial dynamic modulus in consideration of the influence of compaction degree was established, and the holistic process curve of dynamic modulus attenuating with the change of compaction degree was also obtained. In addition, the normalized dynamic modulus and damping ratio of desulphurized gypsum showed little difference. The range of reference dynamic strain of desulphurized gypsum was given as 1×10^-4~4×10^-4.

Key words: desulphurization gypsum, degree of compaction, dynamic modulus, damping ratio, dynamic strain, normalization