高温作用下花岗岩三轴蠕变特征的实验研究

采用中国矿业大学的"20MN高温高压岩体三轴试验机",对Φ200mm×400mm大尺寸花岗岩试件在高温下的蠕变特征进行了试验研究。介绍了三维应力作用下花岗岩在高温条件下的蠕变试验方法和结果,结合理论与试验结果分析,发现了花岗岩在300℃时轴压94MPa围压75MPa时花岗岩经历蠕变的第一阶段和第二阶段,蠕变变形逐渐停滞,呈现明显的稳态蠕变的特征;在400℃,轴压125MPa围压100MPa时,呈现明显的非稳态蠕变特征。试验还揭示了花岗岩的蠕变性随温度和应力的升高而增强,蠕变性态转变的温度门槛值为300℃～400℃。试验结果对核废料的深埋处置长久安全性,地热能的长期稳定开发都有重要的指导意义。

Experimental study on triaxial creep properties of granite under high temperature

By use of the 20 MN servo-controlled triaxial rock testing machine with high temperature and high pressure in China University of Mining and Technology, experimental study is carried out on the creep properties of large size granite specimens of Φ200 mm×400 mm under high temperature. The creep test methods and results of granite under a three-dimensional stress and high temperature are described. Based on the theory and the analysis of test results, it is discovered that granite experiences the first and second phases of creep at 300 ℃, axial stress of 94 MPa and lateral stress of 75 MPa. At the same time the creep deformation of granite shows clearly the characteristics of the steady-state creep and gradually stops. But at 400 ℃, axial stress of 94 MPa and lateral stress of 75 MPa, the deformation shows obvious characteristics of the non-steady-state creep. The research reveals that the creep properties of granite increase with the increase of temperature and stress. There is a threshold of temperature about transition from the steady-state creep at 300℃ to the non-steady-state creep at 400℃. Data obtained from experiments are of important guiding significance for the long-term security of nuclear waste disposal in the deep granite and long-term exploitation of geothermal energy.