Evaluation Of Water Resistant Capacity In Coal Seam Floor And Project Example Analysis

Evaluation of water resistant capacity in coal seam floor is an importantresearch of mining on confined water. It is mainly affected by physical andmechanical propertied, structure, thinkness, mining parameters and waterpressure. In order to study the function of the various factors which affect themechanism of resistant capacity, theoretical analysis, field testing, numericalsimulation are combined in this paper. Water resistnat principle and evaluationindex are analyed. The water resistant capacity of NO.1coal seam floor inNO.412mining zone of a coal mine in Huainan is tested and evaluted, then aseries of proper parameters are supplied to this coal mine. The mainconclusions of this study are as follows:1. Water inrush of coal seam floor is affeced both by the extension ofcracks and the arising of confined water. If there is a fault zone in coal seamfloor, the chance of water inrush will be increase. And the different expansionmechanism is appeared in different rockmasses interfaces.2. Triaxial compression and permeability test results showed that: theimpermeability of mudstone is best, sandy mudstone follows, and finesandstone is worst. The rock permeability increases with the load increasingbefore the peak strength, and the maximum permeability has a delay of it.3. The water resistant capacity of coal seam floor is affected by itself,which performed by thickness, strength and rock mess combination. Therewill be a stess relief zone under mined coal zones, when the sum of confiningpressure and rock mass compressive strength is less than hydraulic pressure,then the water inrush will occur.4. Numerical analysis of mining effect to10different types of rock massstructure layered floor was carried out by FLAC, the analysis by adjusting thecoal face width, various parameters such as face excavation length, thicknessof the cola seam floor, water pressure, weak interlayer position and faultcutting scale was adjusted to find out theirs influence of on the field floorstress and destruction.5. The rockmass structure of the top section of coal seam floor in NO.412 mining zone is block complete structrue, the lower section is block structureand the bottom section is layered structure. Hydraulic fracturing test arecarried out in bottom and middle sections of the coal seam floor to determinethe maximum rupture pressure of water. Numerical simulation of miningeffect in coal seam floor is carried by using FLAC, then the breakage law ofcoal seam floor is analyzed.6. When the mining face is90m long, the effectively impermeablethickness of coal seam floor is about2.4m. For security reasons, relevantpersonnel should strengthen the exploration of fractures in coal seam floor,reinforcement measures should be taken to fractured floor before the recovery.