Creep mechanical properties and damage failure of cross-fractured rock masses with different angles and thicknesses

Abstract

[Objective] In the long-term historical geological activities, there are a large number of fractures in the underground rock mass, which is bound to deteriorate the creep mechanical properties of the rock mass and its ability to resist failure. In order to reveal the influence of the change of fracture angle and thickness on the creep mechanical properties and damage damage of rock mass with cross-fractures under the long-term action of graded cyclic loading and unloading. [Methods] According to the cyclic loading and unloading creep test curves, the energy of each stage of cycling was calculated, and the creep mechanical properties and damage laws of different fractured samples were analyzed by energy dissipation method and acoustic emission technology combined with the strength of the sample. [Results] The results showed that the stress-strain curve of the specimen had an obvious hysteresis circle under graded cyclic loading and unloading, and the angle and thickness of the fracture had a deteriorating effect on both the peak strength and the long-term strength, and the influence of the latter was slightly higher than that of the former. The input energy, elastic energy and dissipation energy of the specimen under different fracture conditions are similar, and the damage variable D value increases with the increase of fracture angle and thickness. The cumulative ringing number of AE will have obvious abrupt changes in the process of loading and unloading, and the abrupt range will be larger when cracks occur in the specimen.[Conclusion] The result show that the irreversible damage caused during the test is the main factor leading to the change of specimen strength from the hysteresis loop and energy damage D value. The larger the crack thickness and angle of the specimen, the earlier the signal appears and increases, and the less stress occurs when the specimen is damaged.

Keywords

crevice / cyclic loading and unloading / creep / damage variable D value / acoustic emission / mechanical properties / influencing factors