Precisely describing the formation and evolution rules of coal-rock fracturing crack have great value on reservoir fracturing improvement and highly efficient mining of coal bed methane well. In this paper, a non-linear dynamic method is used to study crack damage evolution behavior of coal-rock fracturing. Considering distribution characteristics of natural cracks in coal-rock, and based on da...

There are lots of cleats, fractures and many other structure weak planes in coal seams, which make the bullet holes and cleats intersecting. During the hydraulic fracturing process in coal seams, fractures will initiate at coal rock body of borehole wall, and cleats or fractures are different from conventional reservoirs. Thus a new model for initiation pressure calculation during coal seams fr...

Rock strata in a coal mining environment are essentially bedded in nature and hence exhibit specific load-deformation characteristics. Mining may induce shearing as well as separation along the bedding planes which may result in bending and subsequent fracturing of the rock layer. This on the other hand may substantially change the in situ fluid flow properties of the rock mass, such as permeab...

A series of experiments were performed to determine rock mechanical parameters related to was studied. Experimental results show that the coal seam in the study areas has a relatively low elastic modulus, high Poisson’s ratio, high fragility and is easily broken and compressed. The coal seam is considered as a transversely isotropic medium, since the physical properties in the direction of bedd...

Original scientific paper With the increase in mining depths and the occurrence of worsening conditions, deep, large-scale and rapid mining may lead to more complicated dynamic features for tunnels, making them vulnerable to dynamic disasters such as rock bursts and coal/gas outbursts with subsequent heavy damage and casualties. A three-dimensional structural mechanics model for deep stopes was...

Underground rock masses have shown a general trend of natural balance over billions of years of ground movement. Nonetheless, man-made underground constructions disturb this balance and cause rock stability failure. Fractured rock masses are frequently encountered in underground constructions, and this study aims to restore the strength of rock masses that have experienced considerable fracturi...

Underground longwall mining of coal causes large scale disturbance of the surrounding rock mass. The disturbance can increase the rock mass permeability through a reduction on the stress as well as formation of new fractures in the rock. Methane gas contained in the disturbed rock mass can migrate towards the low pressure mine workings and present an explosion hazard. This paper describes the a...

in the present study, an investigation was carried out on parvadeh coal mine in tabas, iran, to survey the effect of fractures on unusual methane gas emission in coal mines. this coal mine was chosen for investigating because of its high methane gas content in the coal body and available data from sensors in desired locations. gas concentration monitoring programs were carried out at the mine s...

The article analyzes the issue of reliable estimate unloading extent and variation order coal-rock massif geomechanical characteristics as a result hydraulic fracturing undertaken from mine workings. For this purpose it is proposed to use value studied rock mass. In case possibility comparison with geological actual data doesn’t exist, option using mass classification based on estimated geophys...

A multisignal nanosecond synchronous acquisition system to measure acoustic emission (AE) and electromagnetic radiation (EMR) generated during the process of loading failure coal rock samples is established. The correlation between energy AE EMR signals stress outburst coal-rock was studied, characteristics fracturing were analyzed. results show that (1) before samples, fluctuation largest, wit...