Mechanical Behaviour of Anchored Rock Containing Weak Interlayer under Uniaxial Compression: Laboratory Test and Coupled DEM–FEM Simulation

Abstract

The reason for instability in a rock mass with a weak interlayer is not only the sliding failure of the rock interlayer structural plane but also the tip crack propagation caused by the stress concentration at the tip of the interlayer. In this study, a uniaxial compression test of an anchored rock mass with a weak interlayer was carried out to determine the influence of the anchorage on the failure pattern and the strength of samples with different interlayer dip angles. In addition, the coupled DEM–FEM numerical simulation method was used to study the internal stress evolution of the sample and the stress distribution of the anchor under the anchorage effect. The results showed that the anchorage effect on reinforcement and strength enhancement was greatest for the sample with an interlayer dip angle of 30°. Under the anchorage effect, crack initiation was limited and there was more shear failure in the samples. The reinforcement range of the anchorage effect for anchors with restrained ends was larger than for anchors with free ends. When the rock–anchor interface was unbonded, the effect of the free-ends anchor reflected the residual friction, but the restrained-ends anchor still worked by limiting the lateral expansion of the rocks. The stress values and deformation of the anchors decreased gradually with an increase in dip angle.

Mechanical Properties and Acoustic Emission Characteristics of Anchored Structure Plane with Different JRC under Direct Shear Test

“…Besides, the elastic modulus of cement mortar is 5.27 GPa. These parameters are in good agreement with the mechanical properties of sandstone [42]. The failure modes of cement mortar and sandstone are shown in Figure 6.…”

“…The typical failure modes of intact sandstone under uniaxial loading can be divided into slope-failure and split-failure [43]. It can be seen in Figure 6, the failure mode of cement mortar is consistent with that of sandstone [42,44], which means the rock-like material used in this paper can well simulate the natural rock.…”

“…The typical failure modes of intact sandstone under uniaxial loading can be divided into slope-failure and split-failure [43]. It can be seen in Figure 6, the failure mode of cement mortar is consistent with that of sandstone [42,44], which means the rock-like material used in this paper can well simulate the natural rock. The peak shear strength of unanchored structural planes under different normal stresses were linearly fitted, and the relationship between peak shear stress of structural plane with different JRC and normal stress was obtained, as shown in Figure 7.…”

Study on Mechanical Properties and Weakening Mechanism of Acid Corrosion Lamprophyre

“…During the static acid etching, the pH value of each solution and the weight of the samples were continuously measured by pH meter and electronic balance when the concentration of some cations in the immersion solution was monitored. In addition, the mechanical properties and failure characteristics of lamprophyre under uniaxial loading were studied [ 28 , 29 ]. Based on the above data, the acidification mechanism of lamprophyre was analyzed.…”

An Investigation of a Floor Treatment Plan for In-Pit Dumps with an Underlying Weak Layer

“…Based on the theory, a discontinuous structural surface consists of a fracture surface and discontinuous rock bridges. During shearing, it is expected that both the fracture surface and rock bridges provide shear resistance [28][29][30]. By assuming the stress is evenly distributed along the shear surface, the continuity coefficient of the structure plane is P and the shear strength of the regenerated structural plane is [28]:…”