砂岩蠕变损伤模型特性

Creep damage model of sandstone

为研究砂岩的蠕变损伤特性,采用TAW-2000电液伺服岩石三轴试验仪对砂岩试样进行了分级加载蠕变试验,通过引入西原体和Kachanov损伤模型,建立了能描述加速蠕变阶段的损伤蠕变模型.试验结果表明,在低应力加载作用下,存在岩石内部裂隙压密和闭合的现象;岩石蠕变特性存在从低应力下的应变硬化逐渐转为高应力下的应变软化的现象;相同围压条件下,高应力下岩石处于稳定蠕变阶段的蠕变速率高于低应力下的蠕变速率.通过Origin软件运用Levenberg Marquardt算法对蠕变损伤模型参数进行辨识,模型曲线与试验曲线吻合度高,验证了所建立蠕变损伤模型的合理性,弥补了西原体难以描述加速蠕变的缺点.

In order to study the creep damage characteristics of sandstone,the TAW-2000 electro-hydraulic servo controlled rock triaxial was used to carry out the graded loading creep test of sandstone samples.By introducing the Xiyuan and the Kachanov damage model,the damage creep model was established to describe the accelerated creep stage.Test results show that the under low stress loading,there are dense and closure of the phenomenon;creep properties of rock exists from low strain of strain hardening gradually turned into high stress strain softening phenomenon of fissures in the rock pressure;under the same confining pressure,rock under pressure in the steady creep stage of creep rate is higher than the low stress creep rate.The parameters of creep damage model are identified by Origin software using the Levenberg Marquardt algorithm.The test curve has a high degree of coincidence,which verifies the rationality of the established creep damage model and makes up for the shortcomings of the Xiyuan body that is difficult to describe the accelerated creep.