Study On Dissolution Test Of Ordovician Carbonate Rock In North-China Typical Coalfields

A large quantity of coal resources threatened by karst water hazard is reserved in the area of carbonate rock where it is estimated to 3.44×10~6km~2 in China and above 1/3 of territory. In order to free these coal resources, research on the control factor of carbonate karst development has important theoretical meaning and engineering practical value.The dissolution test indoor is an important content for the control factor study. The test equipment is designed and made by ourselves with the function of flowing water simulated and 24 samples tested at the same time. The Zangji Huainan, Zhangcun Luan and Dongtan Yanzhou coalmines are taken for examples in test with 3 months lasted and 5 groups, 120 pieces samples tested. As a result of data sorted out and analyzed, the conclusions are summarized as follows:(1) The open systems equipment of dissolution test indoor has obvious advantage than close systems ever, because it can simulate two factors what water erosion and flowing in four foundation factors of karst development.(2) SPSS (Statistical Package for the Social Science), the famous software for statistic in the world, is applied to analyze 7 kinds of mineral compositions with Principal Component Analysis block. Then, multivariate linear regression analysis block is used, in this block calcite content (VAR00001) and dolomite content (VAR00002) as two independent variables, the quantity of dissolution per unit area ((?)) as the dependent variable. The linear regression equations under four kinds of test conditions are showed as follows:①24℃, 16.67ml/min (?)=-0.002+0.014VAR00001 +0.008 VAR00002②15℃, 16.67ml/min (?)=-0.06+0.018VAR00001 +0.011VAR00002③15℃, 60ml/min (?)=-0.05+0.022VAR00001+0.011 VAR00002④24℃, 60ml/min (?)=-0.05+0.026VAR00001+0.013VAR00002In the above-mentioned conditions, the comparative study for the rate of calcite and dolomite dissolution shows that the dissolution rate of calcite is more faster 0.64-1 times than that of dolomite.(3) In Huainan Zhangji coalmine, the dissolution rate of carbonate decrease gradually along with the increase in depth (703.7m-738m), which mainly result from the difference of mineral composition (dolomite content is increasing as the depth increases).(4) The difference of average dissolution rate in different mining area been showed. That is (?)=0.0084g/cm~2 in Huainan Zhangji less than (?)=0.0168g/cm~2 in Zhangcunand (?)=0.0155g/cm~2 in Dongtan.(5) The change of dissolution rate is small -(?)=0.0006g/cm~2- in the small temperature change -15℃and 24℃- slow velocity of groundwater flow. Relatively speaking, the change -(?)=0.0038g/cm~2- is big in high velocity of groundwater flow. And the change result from velocity of groundwater flow is big -15℃, (?)=0.0038 and 24℃, (?)=0.0070- for same temperature.