Experimental Study On Seepage Mechanism Of Jointed Rock

The hydraulics characteristic of jointed rock significantly affects geotechnical engineering ,such as surface water seepage in the mine, forecast and controlling of pressure water of the coal floor, oil, terrestrial heat exploitation, embedding of chemical and nuclear waste, mining design. They all inevitably come down to problems of fissure water movement. Correctly mastering seepage mechanism of jointed rock is theoretical significance and applying value for evaluating of mining safety, forecast of underwater movement, stability of cavity, preventing artificial evocating earthquake, connotation enrichment of rock mechanics.Through combining theory analysis, numerical calculating and applying in practice, test technology of seepage mechanism of jointed rock was systemically analyzed and researched .Fist of all ,on the basis of analyzing seepage characteristic of rock ,hydraulic model of fracture seepage, basic equation of coupling of seepage and press, fracture seepage mechanism under press and evolving rules of penetrability ,it is found that penetrability coefficient between compact rock and jointed rock is significantly various, more than eight number degree. The penetrability of compact rock can not represent that of jointed rock. Darcy model and faults of single jointed rock and MTS characteristic of compact rock can not meet the demand of engineering practice. Through F-RFPA2D numerical simulation calculating, the relativity before and after destroying between penetrability and deformation in the different deformation stage was researched and analyzed. As a result, in the originally compacted stage, the rock penetrability increased when the press was decreased. When the crack occurred inside, the penetrability increased along with press increasing. In the soften stage,the penetrability increased when the crack of jointed rock extended. When the fracture with different thickness and different angle was under different vertical pressure, the penetrability varied. Jointed rock was more easily destroyed under shearing strength. The penetrability changes along with crack extension. The jointed rock deformation resulted from shearing strength significantly affect its penetrability. Though analyzing theory and characteristic of MTS seepage test method, test method for integrated penetrability which come down to press condition, anisotropy, roughness of jointed rock, and occurrence of joint was put forward. And test equipment and design method for jointed rock under shearing strength were given.Combining engineering in HuangLing 1st Coal Mine, excavating seepage mechanism of working face in 3,4 mining area was analyzed. When working face excavated 120m, the rock strata 18m above the roof detached, crack expanded, and first seepage happened and seepage value was 80m3/h; When face excavated 160 m, the crack height was 58 m, seepage increased and the value was 140 m3/h.When face excavated 240m, the crack extended 120m above the coal. The face seepage value was 105m3/h and identical with numerical simulation. When face excavated 280m, crack ran through the floor of staunch strata. Crack rock seepage increased and the value was 140m3/h. When face excavated 320 m, the crack ran through the floor of staunch strata, the seepage value was 105m3/h. Seepage value of numerical simulation coincided with that of practice test, which proved the coincidence between seepage mechanism of jointed rock and practice. So opening out seepage testing equipment of jointed rock was nessary.