Abstract
Natural rock masses have many internal joints, fractures and faults, which greatly influence their mechanical properties during geological processes. In this paper, considering different joint angles and rock-bridge angles, uniaxial compression numerical tests on double-fractured red sandstone based on particle flow code (PFC) were carried out. The influence laws of the mechanics, acoustic emission (AE) and damage evolution characteristics of double-fractured sandstone under different crack geometry conditions were analysed. The results indicated that the peak stress and elastic modulus increase with increasing fracture angle. The peak stress and elastic modulus of rock samples first increase and then decrease with the increase in the rock-bridge angle, exhibiting a nonlinear distribution; when the angle β (rock-bridge angle) is less than or equal to 45°, the peak strain differs only slightly and decreases gradually with the increase in the rock-bridge angle. There are three stages in the AE evolution of fractured red sandstone: The initial emission of AE, the increase in AE and the decline in AE. The influences of different fracture angles and rock-bridge angles on the AE characteristic rule of rock samples vary. The damage evolution process of sandstone specimens with different joints can be divided into four stages: Initial damage, stable increase, accelerated development and stable damage. The fracture angle mainly affects the damage stage. The smaller the angle of the crack is, the greater the strain value in this stage. The rock-bridge angle mainly influences the damage variable evolution during the stable increase, accelerated damage development and stable damage stages.
Highlights
With the increase in mining scale and development depth, coal mine disasters, such as rock burst and roof collapse are becoming increasingly serious
The results showed that the peak strength and elastic modulus of rock samples decrease with the increase in the crack angle, and the regularity among the rock-bridge angle, the gap of the cracks and the mechanical parameters were not obvious
Deformation or fracture will occur when rock is subjected to stress, and the release of strain energy in the form of elastic wave is called acoustic emission (AE)
Summary
With the increase in mining scale and development depth, coal mine disasters, such as rock burst and roof collapse are becoming increasingly serious. There are four main coalescence models: Tension, compression, shearing and mixing coalescence These studies have great significance in the determination of the mechanical behaviour and failure mechanisms of jointed rock mass. The mechanical behaviour and damage evolution characteristics of the different joints in precast fractured rock mass still need to be studied. The study of rock damage evolution is of great significance to deeply understand rock fracture mechanism and prevent disasters and accidents caused by rock damage In this manuscript, based on the above researches, particle flow code (PFC) was first used to establish a uniaxial compression model of double-fractured rock with different geometries, and the characteristics of the mechanics and AE of double-fractured red sandstone under the conditions of different joints and rock-bridge angles were analysed. A damage constitutive model of rock mass based on AE characteristics was proposed, and the damage evolution law of double-fractured rock mass was explored
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
