Abstract
Stress relief method is widely used in coal mines in many countries to prevent the gas outburst and rock burst. It is one of the effective methods to relieve the stress by boring in coal seams.
The author made a model experiment to investigate the effect of the boring bored near fractured zone at the heading face on the stress relief. A three-dimensional model experimental apparatus of about 1: 80 geometrical scale was used. As the model rock mass, the gypsum plate was used and as the model coal seam, an artificial seam made from the mixture of water, gypsum and diatomite was used. The scale factor of the stress and strength was 1: 40.
The effect of the stress relief was measured by varying the location of fractured zone, the thickness of fractured zone and the strength of model coal seam. The effect of the stress relief was evaluated by the degree of stress relief defined by the author. The characteristics of the stress distribution near the fractured zone and the relationship between the degree of the stress relief and the above experimental parameters were reported.
