压实度对脱硫石膏动模量和阻尼比的影响试验研究

为研究不同压实度下脱硫石膏动模量与阻尼比特性,分别对压实度为0.85,0.90,0.95的3组脱硫石膏试样进行动三轴试验。试验分为等压固结和偏压固结试验2部分,等压固结试验固结应力比为1,围压分别为100,200,400 kPa;偏压固结试验围压为100 kPa,固结应力比分别为1.0,1.5,2.0。试验结果表明:随压实度增大,脱硫石膏动模量逐渐增大,阻尼比在动应变＜10^-5时差异不明显,动应变＞10^-5时逐渐减小;初始动模量与压实度具有良好的幂相关关系,建立了考虑压实度影响的初始动模量公式,进而推求了考虑压实度影响的动模量衰减全过程曲线;归一化的脱硫石膏动模量和阻尼比差异较小,试验用脱硫石膏参考动应变取值范围为1×10^-4~4×10^-4。

Influence of Compactness on Dynamic Modulus and Damping Ratio of Desulphurized Gypsum

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.