In view of the typical anisotropy of columnar jointed basalt in the dam area of the Baihetan Hydropower Station on the Jinsha River in China, columnar jointed rock mass models with different column angles (α = 0°–90°) were constructed with similar materials, and three sets of intermittent joints are considered in the physical models. Uniaxial and equal-confining-pressure triaxial compression tests were carried out with a true triaxial testing machine, and the variations of the failure mechanisms, stress-strain relationships, and strength characteristics of the columnar jointed rock masses with the joint inclination angle were investigated under different stress conditions. The results revealed the following: 1) during triaxial compression, two types of stress-strain curves existed, namely the ideal plastic curve and the strain-hardening curve; 2) the strength and elastic modulus of the sample under uniaxial compression presented U-shaped curves with the variation of α. Moreover, the strength of the samples increased with the change of α under triaxial compression, and the elastic modulus Er increased significantly with the increase of the confining pressure. 3) There were four typical types of failure within the columnar joint samples under triaxial compression. In addition, the test data were used to verify that the Mogi strength criterion good applicability to the columnar jointed rock mass under three-dimensional stress. An empirical prediction model of the relationship between the elastic modulus and confining pressure of the columnar jointed rock mass was established, and its applicable conditions were analyzed. The empirical prediction model is verified by the test results of the columnar jointed rock mass, which indicates that the prediction model was in good agreement with the test data. Finally, the strength characteristics and failure modes of columnar jointed rock masses under different loading conditions were summarized.
Experimental Study on the Strength Failure Characteristics of Columnar Jointed Rock Masses under Three-Dimensional Stress
KSCE J Civ Eng
KSCE Journal of Civil Engineering ; 25 , 7 ; 2411-2425
2021-07-01
15 pages
Article (Journal)
Electronic Resource
English
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