Evolution of mechanical properties of granite at high temperature and high pressure
Evolution of mechanical properties of granite at high temperature and high pressure
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DOI：
10.1007/s40948-017-0052-8
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发表时间：
2017-01
影响因子：
5
通讯作者：
Yangsheng Zhao;Z. Wan;Zi-jun Feng;Z. H. Xu;Weiguo Liang
中科院分区：
文献类型：
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作者：
Yangsheng Zhao;Z. Wan;Zi-jun Feng;Z. H. Xu;Weiguo Liang
岩石工程，如地热和深部油气资源开发、核废料地下深部地质处置等，都与岩石在高温高压下的力学特性密切相关。本研究报道了利用微ct技术、声发射（AE）技术和600℃20MN伺服控制三轴压缩系统进行高温高压岩石测试，研究高温高压下花岗岩细观结构演化、声发射特征和宏观力学性能演化。实验结果表明：(1)花岗岩在200℃时很少出现微裂纹，而在500℃时出现糜棱质晶状颗粒结构。(2)声发射特征表明，花岗岩热裂具有间歇性和多阶段性。在热裂作用下，花岗岩渗透率也呈现出几个峰值。(3)在相当于埋深1000 m的应力状态下，从室温到600℃，热变形和热膨胀系数都有不同的阶段。三轴压条件下的热膨胀系数比无围压条件下的热膨胀系数约小20倍，说明该参数受围压影响较大。花岗岩在高温下的破坏方式与室温下一样，均为剪切破坏。但应力-应变曲线与常温下表现出不同的特征。(4)在围压作用下，花岗岩的弹性模量具有不同的周期。总的来说，它随着温度的升高而降低。
Rock engineering works, such as geothermal and deep hydrocarbon resource development and deep underground geological disposal of nuclear waste, are closely related to the mechanical properties of rocks at high temperature and high pressure. This study reports on the use of the micro-CT technique, acoustic emission (AE) technique and the 600 °C 20MN servo-controlled trixial compression system for rock testing under high temperature and high pressure to study the evolution of mesostructure, AE characteristics and the evolution of macro-mechanical properties of granite under high temperature and high pressure. The results obtained from the experiments show that: (1) Very few micro-cracks occur when granite is at 200 °C, while mylonitic crystal granular structures appear at 500 °C. (2) AE characteristics indicate that the thermal cracking of granite is intermittent and multi-stage. Under the influence of thermal cracking, the permeability of granite also presents several peaks. (3) Under the stress state equivalent to 1000 m buried depth, the thermal deformation and the thermal expansion coefficient both have different stages from room temperature to 600 °C. The thermal expansion coefficient under triaxial pressure is approximately 20 times less than the coefficient without confinement, showing that this parameter is profoundly affected by the confining pressure. The failure mode of granite under high temperature is shear failure, just as under room temperature. The stress–strain curve, however, presents different characteristics compared to those under room temperature. (4) When subjected to confining pressure, the elastic modulus of granite has different periods. Overall, it decreases with the increase of temperature.