【摘要】 采用中国矿业大学的"20MN高温高压岩体三轴试验机"进行高温三维应力下大尺寸φ200mm×400mm鲁灰花岗岩蠕变特性的试验研究,温度最高达600℃,轴向应力最高达175MPa。研究发现:(1)三维应力条件下鲁灰花岗岩300℃,500℃的轴向蠕变和300℃,500℃,600℃的体积蠕变变形均可划分为:瞬态蠕变阶段、稳态蠕变阶段和加速蠕变阶段。(2)高温三维应力条件下,鲁灰花岗岩试样的体积、长度和半径随蠕变时间的增加出现增长,这是因为热破裂引起岩石的内部产生了大量的微裂纹,同时还发现试样的侧向比轴向变形增长的速度变形快。(3)以试验结果为依据将静水应力引发体积蠕变,差应力引发轴向蠕变作为三维应力状态下黏弹塑性问题的假设,导出三维应力条件下Burgers体模型体积蠕变的本构方程。(4)通过对蠕变曲线的分析发现,可以用Burgers体模型来模拟鲁灰花岗岩300℃,500℃的轴向蠕变和300℃,500℃,600℃的体积蠕变,并且求出模型的参数。更多还原

【Abstract】 By making use of the 20 MN servo-controlled triaxial rock testing machine with high temperature and high pressure of China University of Mining and Technology,the experimental studies of creep properties of large-size granite specimens of φ 200 mm×400 mm with temperature up to 600 ℃ and axial stress up to 175 MPa are carried out. This research reveals:(1) Under three-dimensional stress,the axial creep deformation at 300 ℃ and 500 ℃ and volumetric creep deformation at 300 ℃,500 ℃ and 600 ℃ of Lu Gray granite show three stages:primary creep stage,stable-state creep stage and accelerating creep stage. (2) Under high temperature and 3D stress,the volume,length and radius of Lu Gray granite increase with time because of fissure caused by thermal cracking in rock. The lateral deformation was more rapid than axial deformation at the same time. (3) It′s the basic hypothesis of visco-elastoplastic problem under three-dimensional stress that differential stress causes axial creep;hydrostatic stress causes volumetric creep deformation based on experimental data;and the volumetric creep constitutive equation of Burgers model under three-dimensional stress is also proposed. (4) Through the analysis of creep curve,it′s proper to simulate axial creep at 300 ℃ and 500 ℃ and volumetric creep at 300 ℃,500 ℃ and 600 ℃ with Burgers model and to calculate model parameters.更多还原