The Mechanical Behavior and Constitutive Model of Brittle Rocks

• Main Authors: Wen, Bin-Hwang, 溫彬煌
• Other Authors: Pan Yii-Wen
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/18993762733850365456

碩士 === 國立交通大學 === 土木工程學系研究所 === 85 === A series of experimental work were carried out previously in NCTU (National Chiao - Tung University) to investigate the mechanical behavior of brittle rocks under elevated pressures and temperatures. In this study, the experimental data of triaxial compression tests is summarized and re-analyzed. Furthermore , the study develops a constitutive model to describe the mechanical behavior of brittle rocks. The experimental results show that crack-closure siginificantly affect the initial stress - strain relation of a brittle rock during triaxial compression. The initial stress - strain curve reveals that the tangent stiffness gradually increases and reaches an elastic stiffness at a crack- closed strain. As the confining pressure increases, the elastic stiffness raises while the crack-closed strain decreases. The effect of temperature on the elastic stiffness and the crack - closed strain , however, is still not concluded from the experimental data. For the post - peak behavior , the class II behavior is obvious. On the basis of the experimental results, a constitutive model is proposed to d escribe the mechanical behavior of brittle rocks. The presented constitutive model contains a pore/crack closure model and a continuum damage mechanics model. The study also developes a computer program behavior optimiz -ation procedure for calibrating the appropriate material parameters from a set of experimental data. By comparing the simulated and experimental results , it is demonstrated that the proposed model can closely simulate the stress- strain relation of brittle rocks with very limited material parameters. Parametric studies also demonstrate that, with proper combination of parameters,the proposed model is capable of modeling (i) the class I as well as the class II post-peak behavior,and (ii) the dilatancy during a compression test.