Numerical simulation study on shear resistance of anchorage joints considering tensile–shear fracture criterion of 2G-NPR bolt

Abstract

Abstract2G-NPR bolt (the 2nd generation Negative Poisson’s Ratio bolt) is a new type of bolt with high strength, high toughness and no yield platform. It has significant effects on improving the shear strength of jointed rock mass and controlling the stability of surrounding rock. To achieve an accurate simulation of bolted joint shear tests, we have studied a numerical simulation method that takes into account the 2G-NPR bolt's tensile–shear fracture criterion. Firstly, the indoor experimental study on the tensile–shear mechanical properties of 2G-NPR bolt is carried out to explore its mechanical properties under different tensile–shear angles, and the fracture criterion of 2G-NPR bolt considering the tensile–shear angle is established. Then, a three-dimensional numerical simulation method considering the tensile–shear mechanical constitutive and fracture criterion of 2G-NPR bolt, the elastoplastic mechanical behavior of surrounding rock and the damage and deterioration of grouting body is proposed. The feasibility and accuracy of the method are verified by comparing with the indoor shear test results of 2G-NPR bolt anchorage joints. Finally, based on the numerical simulation results, the deformation and stress of the bolt, the distribution of the plastic zone of the rock mass, the stress distribution and the damage of the grouting body are analyzed in detail. The research results can provide a good reference value for the practical engineering application and shear mechanical performance analysis of 2G-NPR bolt.

The Physical Behavior of Protected Coal Seams Based on Triaxial Unloading Conditions

“…The calculation was carried out according to Equation (19), and the variation curve of the deformation modulus of the coal samples with the surrounding pressure during unloading was plotted, as shown in Figure 5.…”

“…Numerous scholars have studied the deformation and damage characteristics of the overlying and underlying coal rock layers during protective seam mining through numerical simulation and analyzed parameters such as the stress change characteristics and expansion and deformation rates of the protected layer. These studies provide practical reference values for coal and gas protrusion, gas extraction, and coal and gas co-mining [18][19][20][21][22]. At the same time, laboratory physical similarity simulation tests have also been widely used to study the mechanical properties and damage characteristics of the overlying coal seams during protective seam mining, which is also the most common approach adopted when providing reference values for practical engineering [23][24][25].…”