岩石热力损伤破坏的能量准则研究

Research on Energy Criterion of Thermal-mechanical Coupling Damage of Rock

采用MTS 810液压伺服试验系统及MTS 652.02高温炉对高温下(常温～1 200℃)花岗岩的宏观力学特性进行了较为系统的研究。基于不可逆热力学理论,采用连续损伤力学方法,推导了岩石热力耦合粘弹性损伤余能释放率的理论表达式,建立了岩石热力耦合损伤破坏的能量准则。研究表明,花岗岩的峰值强度和弹性模量随温度的升高总体呈下降趋势,岩样损伤余能释放率随温度的升高和时间的延长而增大,时间对岩石破坏进程产生了较大的影响,在进行理论分析时应考虑时间效应。这比用传统的单一结构损伤参量所建立的损伤破坏准则更全面,更适用于处理岩石热力耦合损伤破坏行为。研究成果为核废料的存储、煤与油页岩的现场气化、深部资源开采、地热资源开发、煤层瓦斯的安全抽放和综合利用等重大工程中的岩石热力学问题提供了有益的研究资料。

Mechanical characteristics of granite under temperature （from normal to 1 200 ℃ ） have been researched with MTS 810 hydraulic servo system and MTS 652.02 high furnace. Theoretic expression of rock complementary energy discharge rate of visco-elastic damage by considering thernlal-mechanical coupling has been derived based on irreversible thermodynamics theory. And the energy criterion of thermal-mechanical coupling damage fracture of granite has also been established. The result shows that peak strength and elastic modulus of granite decreases with rise of temperature and the complementary energy discharge rate of thermal-mechanical coupling damage increases with the rising of temperature and time. The time has great influence on rock failure process,so the time effect must be considered in theoretic analysis. The energy crite- rion established in this paper is more comprehensive and acceptable for dealing with rock thernlal-mechanical coupling dam- age than the failure criterion established by traditionally single damage parameter. Research findings provide valuable basic references for solving problems of rock thermodynamics in reposition of nuclear waste, practical gasification of coal and oil shale, deep resources mining, exploitation of geothermal resources and safety withdrawal and comprehensive utilization of coal seam gas.