Strength, fragmentation and fractal properties of mixed flaws

Advances in Materials Science and Engineering

2017

This paper investigates the influence of joint geometry parameters on the characteristic stress, failure pattern, and energy mechanism of multiple jointed rock-like specimens under uniaxial compression. Both the laboratory and numerical results show that the higher value of UCS occurs when is around 0 ∘ and changes from 15 ∘ to 30 ∘ or when is around 30 ∘ and changes from 45 ∘ to 75 ∘ . However, the lowest value appears when is around 45 ∘ and changes from 15 ∘ to 30 ∘ . The CDiS (critical dilatancy stress) and CIS (crack initiation stress) show a similar tendency to UCS. Moreover, the specimens present different failure modes for various levels of , , and , and the failure mode can be classified into four categories: stepped path failure; failure through parallel plane; failure through cross plane; material failure. In addition, with higher strength, the input energy and strain energy are higher than those with lower strength. Dissipation energy is affected by the failure modes of the specimens. At the same time, when changes from 0.2 to 0.6, the boundary energy, strain energy, and dissipation energy show a decreasing trend.

Section: Specimenmentioning

confidence: 76%

Experimental and Numerical Study of Failure Behavior and Energy Mechanics of Rock-Like Materials Containing Multiple Joints

Cao

Advances in Materials Science and Engineering

2017

“…In Figure 4(a), the ubiquitous joints created by inserting mica sheets into fresh cement mortar are shown [20]. e mica sheet has also been used by other scholars to investigate the failure characteristics of jointed rock mass [21]. Because of the strength of the mica sheet and relatively low interface between mica sheet and mortar, the mica sheet is suitable for modelling the joints which can be filled up with clay.…”

Section: Experimental Materials and Specimen Preparationmentioning

confidence: 99%

“…Actually, there are relatively few scholars who conducted experiments to investigate the failure process of jointed rock mass under restrictive shear loading. Zhang et al [21] has investigated the mechanical behavior of rock-like specimen mixed flaw, and the strength, fragmentation, and fractal properties have been discussed. For the mixed flaws, the length of edge-notched flaw and imbedded flaw is 10 and 30 mm, respectively.…”

Section: Shear Loadingmentioning

confidence: 99%

See 1 more Smart Citation

Crack Initiation, Propagation, and Failure Characteristics of Jointed Rock or Rock‐Like Specimens: A Review

Cao

Advances in Civil Engineering

Fan

et al. 2019

Self Cite

Rock masses are heterogeneous materials containing a large number of discontinuities, and the failure of the natural rock mass is induced by the crack propagation and coalescence of discontinuities, especially for the rock mass around tunnel or underground space. Because the deformation or failure process of jointed rock mass exhibits strongly nonlinear characteristics, it is also very difficult to predict the strength and failure modes of the rock mass. Therefore, it is very necessary to study the failure mechanisms of jointed rock mass under different stress conditions. Apart from the stress condition, the discontinuities geometry also has a significant influence on the mechanical behavior of jointed rock mass. Then, substantial, experimental, and numerical efforts have been devoted to the study of crack initiation, propagation, and coalescence of rock or rock-like specimens containing different kinds of joints or fissures. The purpose of this review is to discuss the development and the contribution of the experiment test and numerical simulation in failure behavior of jointed rock or rock-like specimens. Overall, this review can be classified into three parts. It begins by briefly explaining the significance of studying these topics. Afterwards, the experimental and numerical studies on the strength, deformation, and failure characteristics of jointed rock or rock-like materials are carried out and discussed.

“…However, the mechanical and safety characteristics of rock mass engineering are more affected by joints [23][24][25][26][27]. erefore, the shear mechanical properties of joints are especially important [28][29][30][31][32]. In the freezing-thawing cycle environment, joints are more susceptible to freezing-thawing cycle and cause the shear strength of the rock mass to deteriorate, and these factors will lead to rock mass failure.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cyclic Freezing-Thawing on the Shear Mechanical Characteristics of Nonpersistent Joints

Lei

Advances in Materials Science and Engineering

Chen

et al. 2019

The effects of freezing-thawing cycles and persistency differences have a significant impact on the shear mechanical properties of joints. In this paper, a series of joints direct shear tests were performed on freezing-thawing treated joints to investigate the effect of freezing-thawing cycles and the persistency on the shear strength deterioration of joints. Shear strength and residual strength decrease with the freezing-thawing cycle increase and joint persistency increase. Shear strength damage mainly generates in the initial stage of the freezing-thawing cycle, and the shear strength decreases slightly in the late freezing-thawing cycle stage. The freeze-thaw cycle has a minimal effect on the shear strength of joints with low persistency, yet has a great effect on joints with high persistency. The damage of joint roughness caused by freezing-thawing cycles increases with joint persistency increases. When the joint persistency is constant, the shear strength parameter decreases with the freezing-thawing cycle at first and then tends to be stable. Cohesion is the dominant factor that controls shear strength. When freezing-thawing cycles are constant, the friction angle decreases slowly with persistency at first and then decreases rapidly, and the friction angle is the dominant factor that controls shear strength.