Abstract
The joint planes in fractured rock mass will reduce the tensile strength and shear strength of rock mass, which has a decisive influence on the deformation and failure mode of engineering rock mass. Furthermore, infill also exists between the joint surfaces, which will also affect the shear characteristics of the joint. A method of importing standard joint profile into PFC2D was proposed, and a series of numerical simulation tests were carried out to study the effect of joint roughness and infill thickness on the shear characteristics of joints. The numerical results revealed that rock bolts profoundly improved the shear strength of the infilled rock joints, enhanced the toughness of the joint surface, increased the number of micro-cracks, and made the dilatation more obvious. The shear stress and the normal displacement of unbolted or bolted infilled rock joints increased with increasing the joint roughness and decreasing the infill thickness. The maximum horizontal compression stress in the middle of the bolt gradually increased with the increase of joint roughness coefficient. Different roughness has different effects on the number of micro-cracks in the sample. The number of total cracks and tensile cracks of the bolted and unbolted specimens increased with the increase of joint roughness coefficient, while the shear cracks remained almost the same. Through the study of the coupling effect of joint roughness and infill thickness on peak shear stress, results can be obtained as follows. The unbolted samples are highly sensitive to JRC changes. The greater the infill thickness, the greater the sensitivity of unbolted samples to JRC changes. The reinforcement effect of the bolt will strengthen the meshing strength between the joint surface and the filling material; that is, the meshing strength is positively correlated with joint roughness and negatively correlated with filling thickness.
Highlights
Rock mass is formed through long-term and complex geological processes; as discontinuous structural planes, joints are widely distributed in rock mass. e existence of joints will greatly reduce the strength of rock mass and increase the deformation of rock mass
For bolted sample, when infill thickness increases, this change rate gradually decreases, from 1.45 to 1.25. e above results indicate that the unbolted samples are highly sensitive to JRC changes
A method of importing standard joint profile into PFC2D was proposed. rough a series of numerical shear tests, the shear characteristics and micro-cracks of infilled rock joints have been discussed in detail under different JRC and infill thickness conditions. e influence of bolting structure was considered
Summary
Rock mass is formed through long-term and complex geological processes; as discontinuous structural planes, joints are widely distributed in rock mass. e existence of joints will greatly reduce the strength of rock mass and increase the deformation of rock mass. Due to the advantages of convenient processing and installation, high efficiency, and effective improvement of the strength and stability of jointed rock mass, bolt is widely used in geotechnical engineering to reinforce the rock mass [10]. Saadat et al [21] and Shang et al [22] used discrete element simulation to study the shear behavior of bolted rock joints. In order to study the influence of joint roughness, filling thickness, and anchor structure on the shear characteristics of jointed rock mass, and the development law of microcracks, a method was proposed to digitize the standard joint profile and import them into numerical model, and a series of numerical simulation experiments were carried out
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