温度-应力耦合作用下无烟煤的蠕变特性与本构关系研究

为了研究无烟煤在温度-应力耦合作用下的蠕变特性,采用自主研发的多功能三轴岩石力学试验机,通过理论分析与物理试验相结合的方法,进行了轴压20 MPa、围压4 MPa、不同温度(30、60、90℃)条件下的三轴蠕变试验。研究结果表明:瞬时应变随温度的升高而非线性增大,30℃、60℃、90℃条件下的瞬时应变分别为0.666%、0.9084%、1.2727%;温度的上升可以增加煤体减速蠕变和稳态蠕变的损伤过程,在72 h的蠕变过程中,30℃、60℃、90℃条件下的蠕变应变分别为0.503%、0.5816%、0.6863%。基于非线性流变力学理论,建立了1个非线性的黏弹塑性本构模型,根据蠕变试验结果,采用曲线拟合法对该模型进行拟合。结果发现吻合效果良好,说明该模型可以较好的描述无烟煤在温度-应力耦合作用下的蠕变过程。

Creep Properties and Constitutive Relation of Anthracite Under Temperature-Stress Coupling

To study the creep characteristics of anthracite under temperature-stress coupling,the muti-functional rock testing machine was used to conduct the tri-axial creep tests under the confining pressure of 20 MPa,the axial pressure of 5 MPa,and the temperatures of 30℃,60℃and 90℃,respectively.The results show that the instantaneous strain increases nonlinearly with the increase of temperature.The instantaneous strain at 30°C,60°C and 90°C is 0.666%,0.9084%and 1.2727%,respectively.The increase of temperature can increase the damage process of deceleration creep and steady state creep of coal.During the creep process of 72 h,the creep strain at 30°C,60°C and 90°C is 0.503%,0.5816%and 0.6863%,respectively.Based on the nonlinear rheological mechanics theory,a nonlinear viscoelastic-plastic constitutive model is established.According to the creep test results,the model is fitted by curve fitting method.The results show that the anastomosis effect is good,indicating that the model can better describe the creep process of anthracite under temperature-stress coupling.