Research on Fracture Characteristics and Energy Dissipation of Hard Rock under the Excitation of Ultrasonic Vibration

Abstract

To promote the application of ultrasonic vibration rock crushing technology in underground rock-drilling engineering, it is necessary to investigate the damage and fracture characteristics of hard rock under the excitation of ultrasonic vibration. In this study, the brittle red sandstone was taken as the research object, the rock fracture experiments under the excitation of ultrasonic vibration were carried out, and the macrodeformation of rock samples was monitored by strain gauges. The experimental results show that the strain curve of rock samples under the excitation of ultrasonic vibration can be divided into the compaction stage, elastic deformation stage, and damage stage; with the increase in static load, the maximum intrusion depth and maximum failure depth of rock samples increase exponentially. To study the damage evolution and energy dissipation mechanism of rock samples under the excitation of ultrasonic vibration, a numerical model was established by using particle flow software PFC2D. The results show that the proposed model can effectively simulate the failure characteristics of rock samples under the excitation of ultrasonic vibration. Through the analysis of the displacement field, stress field, and dynamic fracture process of rock samples, the damage and fracture mechanism of rock samples under the excitation of ultrasonic vibration were revealed. In addition, the ultrasonic vibration simulation tests on rock samples were carried out under different static loads, and the number of rock cracks and energy dissipation process were monitored in real time. The results show that static loads can accelerate the initiation and propagation of cracks and improve the utilization rate of rock crushing energy.

Numerical Simulation Research on Energy Dissipation Characteristics of Fish Scale Weir

“…Table 1. Energy dissipation rate of fish scale weir under different working conditions From table 1, it can be seen that in different θ, as the water head h on the weir increases, the total water heads E 1 and E 2 of the upstream and downstream stable sections also increase, and are different θ the E 1 and E 2 values corresponding to the water head h on the weir are not significantly different [10] . As v 1 and v 2 values are the average flow velocity of the calculated cross-section, the surface flow velocity on the cross-section is relatively large, while the bottom flow velocity is relatively small.…”

Mesoscopic Damage and Fracture Characteristics of Hard Rock under High-Frequency Ultrasonic Vibration Excitation

“…The average uniaxial compressive strength and elastic modulus stand at 92.5 MPa and 5.4 GPa, respectively. The natural frequency of the rock samples, determined by the tapping method, is 11,625 Hz [15].…”

“…Zhou conducted a thorough strain monitoring study on the rock sample during ultrasonic vibration excitation, and discovered that the rock experienced three distinct processes of elastic deformation, plastic deformation, and damage progression [14]. Zhang revealed the energy dissipation law of brittle red sandstone under ultrasonic vibration excitation with different static loads [15]. Zhou developed a constitutive model for fatigue damage in granite under ultrasonic vibrational stimulation, and its accuracy was validated via PFC2D numerical simulations [16].…”

Influence of High-Frequency Ultrasonic Vibration Load on Pore-Fracture Structure in Hard Rock: A Study Based on 3D Reconstruction Technology

“…Using an infrared thermal imager, Zhao studied the thermal damage effect of granite under ultrasonic vibration, divided the rock region into an elastic zone, a plastic zone, and a failure zone according to the surface temperature of the rock sample, and proposed that the non-uniform expansion of mineral particles inside the rock and fatigue damage are the main causes of granite fracture [ 15 ]. Zhang analyzed the influence mechanism of static load on rock failure under ultrasonic vibration from the perspectives of displacement field, stress field, fracture field, and energy in combination with tests and numerical simulation [ 16 ]. Yang used the penetration depth of the actuator, the degree of fragmentation, and the number of cracks as three indexes to evaluate the rock-breaking effect of ultrasonic vibration [ 17 ].…”