Fatigue failure identification using deformation and energy rate for hole‐fissure contained granite under freeze–thaw and variable‐frequency–variable‐amplitude cyclic loads

Abstract

This work conducted laboratory tests considering the coupled freeze–thaw (FT) and variable‐frequency–variable‐amplitude cyclic loads on granite containing two fissures and a circular hole. The analysis is dedicated to reveal the deformation and energy rate characteristics. Testing results show that increasing FT cycle and loading level both accelerate rock damage. The rock subjecting to high FT cycle behaves much larger damage rate in terms of volumetric strain and dissipated energy. The warning strength is defined according to the volumetric strain rate and dissipated energy rate which can early issue a warning than the crack damage stress point. In addition, the rock instability precursor is proposed by monitoring the incremental rate of the radial strain and volumetric strain; drastic damage occurs when the volumetric rate exceeds the radial rate. Three typical crack coalescence modes of double shear coalescence, single shear coalescence, and single tensile coalescence were revealed.

On fracture and damage evolution modelling of fissure‐hole containing granite induced by multistage constant‐amplitude variable‐frequency cyclic loads

“…Considerable attentions have also been paid on the fracture mechanism of rock mass containing cavity-like flaws. [14][15][16] It is reported that the fracture behaviors of rock containing hole-like flaws is impacted by the hole orientation, 17 hole shape, 18 hole size, 19,20 hole number, 21,22 and hole arrangement. 23 It is found that rock strength decreases with the increases of hole number and hole size, and the crack propagation path is primarily influenced by the hole arrangement.…”

On the effect of confining pressure on fatigue failure of block‐in‐matrix soils exposed to multistage cyclic triaxial loads

“…Strain rate is generally used to characterize the damage rate of materials under deformation. It is commonly believed that the strain rate of rocks is always positively correlated with the damage degree, regardless of the creep, static, or cyclic loading 31–34 . In this work, the strain rate is defined as the incremental rate of strain (axial or volumetric) at the maximum stress point of each CLS and is obtained by using the difference value of strain for different cycles divided by the elapsed cycle number: (ε n −ε 1 )/( N −1), where ε n and ε 1 are, respectively, the strain of N th and 1st cycle at the maximum stress, as is illustrated in Figure 7.…”

Saturated water‐weakening effects on the compressive behavior of thermally damaged granite

“…The above researches enrich the understanding of the individual factor effect of high temperature and water on granite, while the simultaneous influence of high temperature and water on the strength of granite needs to be further considered when facing the actual working conditions which are usually complex. At present, scholars are mainly focusing on the thermal shock behavior of high‐temperature rocks subjected to water cooling, namely, the hydrothermal coupling 27–30 . The core issue under this coupling condition is the thermal damage caused by the process of heating and rapid cooling of rock.…”

“…At present, scholars are mainly focusing on the thermal shock behavior of hightemperature rocks subjected to water cooling, namely, the hydrothermal coupling. [27][28][29][30] The core issue under this coupling condition is the thermal damage caused by the process of heating and rapid cooling of rock. However, the properties of granite subjecting to high temperatures such as water absorption and microscopic structure will change significantly, as experimental research reported.…”