摘要
高温岩体地热开发及核废料的地下处置等需要对高温高压下花岗岩体的力学行为进行深入细致研究。采用自主研制的"20 MN伺服控制高温高压岩体三轴试验机",投入大量人力、财力和物力,历时0.5 a,系统深入地研究φ200 mm×400 mm的大尺寸花岗岩试样在高温三轴应力下的热变形和破坏特征及其热学和力学参数随温度的变化特征。研究结果表明:(1)在三维静水应力下,花岗岩的热变形可分为低温缓慢变形段、中高温快速变形段及高温平缓变形段等3个阶段。自由状态测定的热膨胀系数会过分夸大,或失真地估计岩石的热膨胀或热力作用,在应力状态下测定的热膨胀系数更能反映实际岩体状态。(2)在高温三轴应力条件下,花岗岩体受压表现出与常温下不一致的变形特征,即先是体积膨胀,当差应力超过一定值后则体积收缩。(3)花岗岩体在高温下的破坏形式是典型的剪切破坏,与常温下的破坏形式一致,但在高温和高围压条件下出现明显的延性转化。(4)在有围压条件下,花岗岩体的弹性模量随温度升高先是缓慢减小,然后快速减小,超过400℃后基本保持不变,与小试件的情况相似。
Extracting heat from hot dry rock（HDR） and nuclear waste disposal both need researches on granite mechanical characteristics at high temperature and high pressure in depth.Utilizing the 20 MN servo-controlled triaxial rock testing machine with high temperature and pressure developed by the authors,the research of thermal deformation and failure characteristics of large size granite samples of φ 200 mm×400 mm at high temperature and triaxial stresses through recent half a year is carried out;and the characteristics of thermo-mechanical parameters such as linear thermal expansion coefficient and elastic modulus changing with temperature,are also achieved.The research results indicate that：（1） Under 3D hydrostatic stress,granite′s thermal deformation course can be divided into slow deformation stage at low temperature,fast deformation stage at medium-high temperature and slow deformation stage at high temperature.Thermal expansion coefficient measured without stress state may excessively magnify the rock′s thermal expansion or thermal effect and will result in wrong conclusion,so the thermal expansion coefficient measured with stress state can reflect the actual state of rock mass.（2） Granite shows feature of expansion in volume at low stress while shrinkage in volume after exceeding a certain stress under high temperature and triaxial stresses.It is a different feature contrasted with that of normal temperature.（3） The failure shape of granite at high temperature is of shear failure,while granite will transform to ductility under high confining pressure and high temperature.（4） The elastic modulus of granite decreases with the increase of temperature under confining pressure.The variety course can be divided into three stages,i.e.slow decreasing stage,fast decreasing stage and constant stage.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2008年第1期72-77,共6页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金重点项目(50534030)
中国矿业大学科技基金项目(2005B001)
关键词
岩石力学
高温
花岗岩
热变形
三轴应力
力学特性
rock mechanics
high temperature
granite
thermal deformation
triaxial stresses
mechanical characteristic
