Analysis on the Difference of Energy Evolution in the Process of Energy Storage Failure of Strong Coal Rush Rock Samples under Different Adaptive Modification Regulation Measures

Current energy to “release” after accumulating + first for the mechanism of rock bursts occurred in analysis of the strategy is accepted by many scholars, based on the existing means of prevention and control of percussive ground pressure, from the angle of the prevention and control of design of the mechanism of impact ground pressure energy regulation, namely, “weakened after the first release +” softened water injection measures and “lead after the first release +” drilling pressure relief measures, for the study of mining under the action of a strong shock tendentiousness rock energy regulatory mechanism; based on rock mechanics experiment, the analysis under different modification measures should be variant energy storage mechanisms of induced damage evolution of rock energy. The mechanism of energy evolution in the modification of strong bursting liability roof rock is revealed. The results show that different modification regulation measures can effectively change the physical and mechanical parameters of target rock samples and realize “hard rock softening or soft rock hardening.” Samples under different modification measures are classified as initial consolidation stage, elastic stage, stage of plastic deformation, yield failure stage, and late stage, the energy evolution is roughly the same as the sample complete natural condition, but the yield failure stage and the destruction of late stage have an obvious difference, which provides favorable conditions for impact ground pressure to prevent. With the help of three characteristic energy indexes of total strain, elastic strain energy, and dissipative strain energy of rock samples, the evolution law of energy indexes under different modification control measures is analyzed. The index of elastic energy consumption ratio is introduced as a precursor feature of rock instability and failure, which indicates the rock impact tendency to a certain extent. The energy regulation mechanisms of “first release+then weakening” water injection softening measures and “first release+then guidance” drilling pressure relief measures are explained theoretically, respectively. However, we should focus on the defects of the corresponding control measures and finally try to make a reasonable combination of different modification measures. Finally, the gradient pressure relief scheme should be considered in order to avoid large stress drop caused by large-scale pressure relief in the region and aggravate the instability of rock mass. The instability of rock mass is further aggravated.

Quantum Approach to Damped Three Coupled Nano-Optomechanical Oscillators

We investigate quantum features of three coupled dissipative nano-optomechanical oscillators. The Hamiltonian of the system is somewhat complicated due not only to the coupling of the optomechanical oscillators but to the dissipation in the system as well. In order to simplify the problem, a spatial unitary transformation approach and a matrix-diagonalization method are used. From such procedures, the Hamiltonian is eventually diagonalized. In other words, the complicated original Hamiltonian is transformed to a simple one which is associated to three independent simple harmonic oscillators. By utilizing such a simplification of the Hamiltonian, complete solutions (wave functions) of the Schrödinger equation for the optomechanical system are obtained. We confirm that the probability density converges to the origin of the coordinate in a symmetric manner as the optomechanical energy dissipates. The wave functions that we have derived can be used as a basic tool for evaluating diverse quantum consequences of the system, such as quadrature fluctuations, entanglement entropy, energy evolution, transition probability, and the Wigner function.

Numerical Investigation on Fracture Mechanisms and Energy Evolution Characteristics of Columnar Jointed Basalts With Different Model Boundaries and Confining Pressures

To reveal the mechanical mechanisms and energy release characteristics underlying progressive failure of columnar jointed basalts (CJBs) with various model boundaries and confining pressures, by combining the meso-damage mechanics, statistical strength theory, and continuum mechanics, inhomogeneous CJB models with different dip angles to the column axis are constructed. In the cases of plane stress, plane strain, and between plane stress and plane strain, the gradual fracture processes of CJBs are simulated under different confining pressures and the acoustic emission (AE) rules are obtained. The results show that: 1) in the case of plane stress, the fracture process of CJBs along direction I orthogonal to the column axis: at the initial stage of loading, the vertical joints and the transverse joints in the CJB specimen are damaged. Then, more columns in the upper middle part are cracked; 2) in the case between plane stress and plane strain, the fracture process of CJBs along the direction parallel to the column axis: at the initial stage of loading, the columnar joints are damaged. Then, the area of the damaged and broken columns at the top of the specimen increases and the crushing degree intensifies; 3) for the case between plane stress and plane strain, the AE energy accumulation before the peak stress is higher than the plane strain state along the direction orthogonal to the column axis. Meanwhile, along the direction parallel to the column axis, this value becomes larger when changing from the state between plane stress and plane strain to the plane strain state. These achievements will certainly improve our understanding of the fracture mechanism and energy evolution of CJBs and provide valuable insights into the instability precursor of CJBs.

Investigation of the Energy Evolution of Tectonic Coal under Triaxial Cyclic Loading with Different Loading Rates and the Underlying Mechanism

It is of great significance to ascertain the mechanical characteristics and deformation laws of tectonic coal that is under complex stress conditions for safe production, but the targeted research in this area is still insufficient at present. This paper performed triaxial tests under cyclic multi-level loading at different rates by using an MTS-815 Rock Mechanics Testing System. The strain characteristics, elastic modulus and energy evolution were obtained in order to explore the effects of the mechanism of loading rate on the evolution of deformation and energy parameters of tectonic coal. The results showed that the irreversible strain and plastic energy increased exponentially with the increase in the deviatoric stress, but the growth rate decreased with the increase in loading rate. Furthermore, the elastic strain increased linearly and the growth rate was essentially unaffected by the loading rate. During the compaction stage, the variation of each parameter was not sensitive to the loading rate; during the elastic and damage stage, the rate increase inhibited secondary defect propagation and improved rock strength. In addition, the stepwise and cumulative energy ratio was defined in order to describe the energy distribution during cyclic loading and unloading. It was found that the decrease in the loading rate was beneficial to the transformation of the total energy into plastic energy. The elastic modulus was the most sensitive to sample damage, but the energy density evolution was able to be used to describe the deformation damage process of tectonic coal in more detail. These findings provide important theoretical support for the tectonic coal deformation law and action mechanism in the damage process that occurs under complex stress conditions.