复合岩层三轴压缩蠕变力学特性数值模拟研究

Numerical analysis of creep mechanical property for bedded composite rock

进行了泥岩与煤的三轴压缩蠕变试验并对蠕变试验结果进行分析,结果表明泥岩与煤在三轴压缩条件下的蠕变特性均可以采用Burgers模型进行描述。分别采用泥岩与煤的蠕变参数作为软、硬岩石材料参数建立了软硬互层复合岩样数值模型,分析了不同层间距、软硬岩体积比及层间界面倾角下复合岩样的蠕变特性。结果表明,软硬岩复合岩样蠕变特性同样满足Burgers模型流变规律;相同应力条件下复合岩样的瞬时应变及稳态蠕变速率均随软岩体积比的增大非线性增大;相同软硬岩体积比下,复合岩样的瞬时应变、黏性应变及稳态蠕变速率受层间距的影响不大;层间倾角由0°增大至60°时复合岩体瞬时应变先增大后减小,稳态蠕变速率则先减小后增大,层间倾角由60°增大至90°时,瞬时应变与稳态蠕变速率均先减小后增大。分析结果对软硬互层岩体蠕变特性的研究具有一定的参考意义。

Tri-axial compression creep testes of mudstone and coal are undertaken and the creep test results are analyzed, it is shown that the creep properties of mudstone and coal matched well with Burg- ers model. The mudstone and coal are regarded as the hard stone and soft stone separately and a numer- ical model of interbedded strata of soft and hard stone was established. Creep properties with different layer spacing, different volume ratio of soft stone and different layer dip angle are analyzed. The nu- merical research results show that, the creep properties of bedded composite rock are also according with the Burgers model; Under the same stress condition, the instantaneous strain and steady creep rate are found to increase nonlinearly as increasing volume fractions of soft stone, while the layer spacing has a small influence on them; With the layer dip angle increasing from 0° to 60°, the instantaneous strain increases initially and then decreases, while the steady creep rate changes inversely, when the lay- er dip angle goes from 60° to 90°, both of them decrease firstly and then increase. The conclusion can provide some reference on the creep characteristic of layered rock.