双轴压缩条件下绿片岩的卸载蠕变特性试验

Biaxial compression creep test of greenschist under unloading condition

对绿片岩进行双轴压缩状态下的加卸载蠕变特性试验,并基于Mohr-Coulomb屈服准则得到塑性元件,将该塑性元件与六元件黏弹性流变模型组合得到复合黏弹塑性流变模型。研究结果表明,当以定侧压比同时施加轴向和侧向荷载时,轴向和侧向应变基本随着荷载等级的增加而增加;当将轴向荷载和侧向荷载同时卸载时,轴向和侧向应变均随荷载等级的不断减小而减小;卸载前后的应力水平差越大,不可恢复的瞬时应变也越大;蠕变试验曲线和理论模型曲线较吻合,说明复合黏弹塑性流变模型能较好地描述绿片岩的蠕变特性。

Biaxial compression creep tests of greenschist under loading and unloading conditions were carried out. A plastic component was employed with the Mohr-Coulomb criterion to form a composite six-component viscoelastic rheological model. If the axial and lateral loads are exerted simultaneously with fixed ratio, the axial and lateral strains will increae with increasing axial and lateral stresses. If the axial and lateral loads are gradually removed simultaneously with fixed ratio, the axial and lateral strains will decrease with decreasing axial and lateral stresses. The unrecoverable instantaneous strain is larger when the stress level differences between the loading and the unloading stages is larger. The comparison between viscoelasto-plastic model and experimental curves shows that viscoelasto-plastic model is applicable for determining the viscoelasto-plastic rheological parameters of greenschist.