Abstract
Failure behavior of granite material is paramount for host rock stability of geological repositories for high-level waste (HLW) disposal. Failure behavior also affects the seepage behavior related to transportation of radionuclide. Few of the published studies gave a consistent analysis on how confinement and water pressure affect the failure behavior, which in turn influences the seepage behavior of the rock during the damage process. Based on a series of laboratory experiments on NRG01 granite samples cored from Alxa area, a candidate area for China’s HLW disposal, this paper presents some detailed observations and analyses for a better understanding on the failure mechanism and seepage behavior of the samples under different confinements and water pressure. The main findings of this study are as follows: (1) Strength reduction properties were found for the granite under water pressure. Besides, the complete axial stress–strain curves show more obvious yielding process in the pre-peak region and a more gradual stress drop in the post-peak region; (2) Shear fracturing pattern is more likely to form in the granite samples with the effect of water pressure, even under much lower confinements, than the predictions from the conventional triaxial compressive results; (3) Four stages of inflow rate curves are divided and the seepage behaviors are found to depend on the failure behavior affected by the confinement and water pressure.
Highlights
Granite is usually considered as a material with high strength, low permeability, and good excavation stability, etc., so that it is always applied as one of the host rocks for the geological repositories for High Level Waste (HLW) disposal [1,2]
Based on the observations and analyses on the failure and seepage behaviors of NRG01 granite samples through a series of laboratory experiments, it is found that the confinement and water pressure have significant influences on the failure properties of NRG01 granite samples, including strength, fracturing patterns and stress–strain response
This work is helpful for understanding the mechanism of the varying seepage features under different confinements and water pressures
Summary
Granite is usually considered as a material with high strength, low permeability, and good excavation stability, etc., so that it is always applied as one of the host rocks for the geological repositories for High Level Waste (HLW) disposal [1,2]. There are several problems requiring more studies: (1) In addition to the strength and deformation behaviors, the fracturing patterns of rock should be studied under the effects of confinement and water pressure, and thereafter, the seepage behaviors should be examined in combination with these failure behaviors; (2) The relationship between the damage process and seepage characteristics are investigated. Aiming at obtaining better pressures, understanding failure mechanism theseepage host characteristics, granite confinements samples cored from thepressures, NRG01 borehole in Alxa area, a candidate area for rock under different and water and in turn, its influence on the seepage. This will include the properties, stress–strain relationships and especially the fracturing patterns which are important properties,stability stress–strain relationships and Thereafter, especially the which are forstrength both mechanical and seepage behavior.
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