Abstract
Universal distinct element code (UDEC) is a simulation software based on the discrete element method, widely used in geotechnical mining. However, in the UDEC, when simulating large-scale excavation, the subsidence of the fractured zone is almost equal to the mining height, which makes the deformation value calculated in the study of gob-side entry retention too large. To solve this problem, in this paper, the double-yield constitutive model is applied to the whole caving zone to analyze the deformation and failure characteristics of surrounding rock along gob-side entry retaining by roof cutting. The results of the simulation are in good agreement with the result of drilling peeking (drilling observation by borehole televiewer) and field condition (observation and measurement in the field). Finally, by using this numerical method, the effects of roadway width, temporary support, and coal side support on the failure of the roof and the arc coal side are studied.
Highlights
Longwall mining is the main method of coal mining in Russia, Poland, and China
Two roadways are needed to meet the basic requirements of coal mining and ventilation. ere are two sources of roadway. e first is to dig new roadway, and the second is to retain the old roadway. e new and original roadways need to leave a certain width of coal pillar, known as coal pillar mining, which will lead to a waste of resources
The roof of the roadway along the gob was cut through the bilateral cumulative tensile explosion, and the roof along the kerf side was supported by the roof cutting support. e overlying strata in the caving zone automatically form the roadside with periodic weighting to retain the roadway
Summary
Longwall mining is the main method of coal mining in Russia, Poland, and China. Generally, two roadways are needed to meet the basic requirements of coal mining and ventilation. ere are two sources of roadway. e first is to dig new roadway, and the second is to retain the old roadway. e new and original roadways need to leave a certain width of coal pillar, known as coal pillar mining, which will lead to a waste of resources. When the height of the roadside backfill exceeds 3.5 m, the roadside backfill stability decreases [3], which limits the application of this method in thick coal seams To address this limitation, a new method of gob-side entry retention by roof cutting (gob-side entry retention hereafter) was proposed by He et al [4]. E overlying strata in the caving zone automatically form the roadside with periodic weighting to retain the roadway To date, this method has been successfully implemented in more than 100 coal mines with varied geological conditions in China. Wang et al [5] establishes a mechanical model of cutting cantilever beam through material mechanics He et al [6] studied the influence of key parameters (height and angle of kerf ) of roof cutting on the Advances in Civil Engineering effect of retaining roadway, the filling characteristics of gob. Results suggest potential applications to guiding the site operation and optimizing the support scheme
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