干燥和饱水炭质板岩流变力学特性与模型研究

Study on rheological mechanical properties and model of carbonaceous slates under dry and saturated states

水是影响岩石流变力学性质的重要因素.采用分级加载方式,对兰渝铁路木寨岭二期隧道炭质板岩开展干燥与饱水状态下的单轴蠕变试验.结果表明:饱水岩样的蠕变量和蠕变速率远大于干燥岩样的相应值,相同应力水平下的蠕变应变可达到干燥岩样的3倍以上,进入稳定蠕变阶段也需要更长的时间.分析岩石的蠕变规律,通过在Burgers流变模型上串联一个非线性粘塑性体,提出改进的非线性损伤流变模型,推导其一维和三维蠕变方程.并对流变模型参数辨识方法进行改进,采用线性递减权重粒子群算法(PSO)和Levenberg-Marqud非线性最小二乘法相结合的方法对试验结果进行参数辨识,结果表明该模型能够很好地描述炭质板岩在不同应力水平下的蠕变特性.

Water is an essential factor to rheological mechanical properties of rock.Creep tests were performed to study the rheological properties of carbonaceous slates in wooden village ridge tunnel of Lan-Yu Railway in dry and saturated state by step load method.The test results indicated that the creep strain and the creep rate of saturated specimens was larger than dry specimens under the same stress level,and its deformation was more than 3 times to dry specimens,and for it get into the stable creep stage also need longer time.Based on the creep characteristics of rock under dry and saturated states,a modified nonlinear damage rheological model is obtained by connecting a nonlinear visco-plastic body with the classical Burgers model in series.Meanwhile,1D and 3D creep equation for rocks is deduced.Furthermore,the rheological model parameter identification method is improved,combined with linear decreasing weight particle swarm optimization（PSO） and Levenberg-Marqud（L-M） nonlinear least squares method.The fitted results of the test data showed that nonlinear rheological model can effectively describe the creep characteristics of carbonaceous slates under different stress levels.