Abstract
Coal burst occurrences are affected by a range of mining and geological factors. Excessive slipping between the strata layers may release a considerable amount of strain energy, which can be destructive. A competent strata is also more vulnerable to riveting a large amount of strain energy. If the stored energy in the rigid roof reaches a certain level, it will be released suddenly which can create a serious dynamic reaction leading to coal burst incidents. In this paper, a new damage model based on the modified thermomechanical continuum constitutive model in coal mass and the contact layers between the rock and coal mass is proposed. The original continuum constitutive model was initially developed for the cemented granular materials. The application of the modified continuum constitutive model is the key aspect to understand the momentum energy between the coal–rock interactions. The transformed energy between the coal mass and different strata layers will be analytically demonstrated as a function of the rock/joint quality interaction conditions. The failure and post failure in the coal mass and coal–rock joint interaction will be classified by the coal mass crushing, coal–rock interaction damage and fragment reorganisation. The outcomes of this paper will help to forecast the possibility of the coal burst occurrence based on the interaction between the coal mass and the strata layers in a coal mine.
Highlights
There are critical locations in coal mines where coal burst can take place
If coal mass can be assumed to perform same as the grains in a numerical model, and joint/cleat are same as the cemented materials between the grains, a new damage model can be implemented inside the modified thermomechanical continuum constitutive model for brittle granular materials, which is a function of the level of coal joint/cleat density
Since the D/B ratio can be directly relevant to the stiffness ratio between the coal mass and the strata layer, it could be taken into account as a criterion to evaluate the effect of the high stiff roof on the converted kinetic energy due to the sudden brittle failure
Summary
There are critical locations in coal mines where coal burst can take place. A number of researchers have classified the main sources of coal burst based on the particular underground geometry of the mine as well as the geological conditions of the coal mine [1,2,3,4,5]. Pan [23] indicated that coal burst can be classified based on the characteristic compression of the rock, the fracture of the roof and the fault potential activation type. Another approach is to classify coal burst based on the converting and accumulation of the strain energy. The most critical condition of a fault-slip is where there is a combination of increasing shear stresses and decreasing normal stresses This combination of stresses can cause a strong coal burst, releasing a considerable amount of seismic energy [16,30]. It should be noted that there are number of significant limitations to precisely forecast coal burst incident based on the energy methods due to the crucial sensitivity of the energy calculations on the value of uncertain materials input parameters
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