Fracture process zone (FPZ) in quasi-brittle materials: Review and new insights from flawed granite subjected to uniaxial stress

On the decay of fracture toughness of sandstone subjected to freeze–thaw cycles

“…For quasi-brittle materials such as rocks and concretes, the initiation and propagation of micro-cracks precede the macroscopic fractures, resulting in inelastic deformation, and this damage zone is the FPZ. 47 Many factors can influence the dimensions of the FPZ, including the loading phases, 47 loading paths, 48 intrinsic properties of the materials 49 , loading methods, 50 loading rates, 51,52 temperatures, 53 and so forth. Zhang and Zhou 47 examined the link between the different cracking levels (these levels were classified by characteristic stresses: micro-crack nucleation stress, crack initiation stress, and crack damage stress) and the development process of FPZ of flawed granite applying deformation features via digital image correlation (DIC) and elastic waves by acoustic emission.…”

“…47 Many factors can influence the dimensions of the FPZ, including the loading phases, 47 loading paths, 48 intrinsic properties of the materials 49 , loading methods, 50 loading rates, 51,52 temperatures, 53 and so forth. Zhang and Zhou 47 examined the link between the different cracking levels (these levels were classified by characteristic stresses: micro-crack nucleation stress, crack initiation stress, and crack damage stress) and the development process of FPZ of flawed granite applying deformation features via digital image correlation (DIC) and elastic waves by acoustic emission. They found that there were no apparent FPZs being reactivated during the stable crack growth phase, and it was the unstable crack growth phase reactivating and intensifying the FPZs developed in the earlier phase.…”

Numerical study on cracking behavior and fracture failure mechanism of flawed rock materials under uniaxial compression

“…[1][2][3][4][5][6] These discontinuous structural planes heavily affect the bearing capacity and failure process of flawed rocks under the action of external compressive stress. [7][8][9][10] Namely, these flaws can weaken the stiffness and strength of flawed rock mass. 7,10 Moreover, the tips in the pre-existing flaws can easily become the sources that new cracks initiate, propagate and link, which further results in the weakening of the mechanical properties of flawed rocks.…”

“…[7][8][9][10] Namely, these flaws can weaken the stiffness and strength of flawed rock mass. 7,10 Moreover, the tips in the pre-existing flaws can easily become the sources that new cracks initiate, propagate and link, which further results in the weakening of the mechanical properties of flawed rocks. 8,9 Consequently, investigating the cracking process and fracture failure mechanism of flawed rocks is rather essential for evaluating the security and stability of engineering rock mass, such as rocky slopes, deep mining, and underground hydropower station.…”

“…Up to now, numerous experimental studies have been performed to primarily investigate the mechanical properties and fracture characteristics of different types of flawed rocks like granite, marble, sandstone, and rocklike materials. [1][2][3][4][5][8][9][10][11][12][13][14][15][16][17][18] For example, Yin et al 12 investigated the coalescence behaviors of double parallel surface flaw-contained granite specimens subjected to uniaxial compression through the digital speckle correlation technology. Li et al 17 carried out uniaxial compression tests on marble specimens with two elliptic holes to study the effects of dip angle on the mechanical properties and cracking behaviors of flawed rocks.…”