State Key Laboratory of the Education Ministry for High Efficient Mining and Safety of Metal Mines

Beijing, China

State Key Laboratory of the Education Ministry for High Efficient Mining and Safety of Metal Mines

Beijing, China
SEARCH FILTERS
Time filter
Source Type

Wang J.-A.,University of Science and Technology Beijing | Wang J.-A.,State Key Laboratory of the Education Ministry for High Efficient Mining and Safety of Metal Mines | Han X.-G.,University of Science and Technology Beijing | Liang C.,University of Science and Technology Beijing | Wang M.-M.,University of Science and Technology Beijing
Gongcheng Kexue Xuebao/Chinese Journal of Engineering | Year: 2017

In top coal caving mining, the state of top coal and overburden strata changes from continuous media to discontinuous and loose aggregate media. It is difficult to theoretically describe the transition and action of mining induced pressure in discrete top coal and fractured overlaying strata. Based on the photoelastic experiment principle, the network structure and the evolution characteristics of force chains in discrete top coal and discontinuous overlaying key strata are investigated during fully mechanized top coal caving mining by employing photoelastic test equipment that allows biaxial loading and bilateral particle flowing. The study shows that overburden load in discontinuous strata displays a complicated network composed by weak and strong force chains. Top coal caving mining destroys the equilibrium of the initial force chain network structure, and a composed beam-arch force chain structure forms in top coal and overlaying strata, where the overburden load is transformed into the front coal seam in the form of strong force chains. With mining face advancing and top coal caving, the beam-arch force chain network in overlaying strata develops, and a larger force chain arch structure forms. Bending, breaking and instable movement of the key strata give rise to an inverse moving of the force chain arching foot and a compaction process of the strong force chain network. The distribution density and intensity of force chains evidently increase, resulting in strong pressure phenomena taking place in the mining face. Under the biaxial loading condition, the effect of the beam-arch force chain structure becomes much evident in the earth. The entire structure of the force chain arch displays perfectly, the structure of the strong force chain network becomes denser, and due to breaking and instability of the key stratum, the pressure phenomenon of the force chain arch in front of the mining face and coal seam manifests much pronounced. © All right reserved.


Li P.,University of Science and Technology Beijing | Li P.,State Key Laboratory of the Education Ministry for High Efficient Mining and Safety of Metal Mines | Miao S.-J.,University of Science and Technology Beijing | Miao S.-J.,State Key Laboratory of the Education Ministry for High Efficient Mining and Safety of Metal Mines
Gongcheng Kexue Xuebao/Chinese Journal of Engineering | Year: 2017

Based on the measured in-situ stress data of the metal mining area in China, 165 sets of data were finally adopted after optimized treatment, which basically covers the distribution area of the main metal mines in the Chinese mainland. The characteristics of in-situ stress field in the buried depth of the metal mining area in China were presented by regression analysis method, and the stability of the fault of the metal mining area in China was discussed from the ground stress. The results show that the vertical principal stress, the maximum horizontal principal stress and the minimum horizontal principal stress in the metal mining area of Chinese mainland generally increase linearly with the depth. The difference between maximum and minimum horizontal principal stresses (Δσ) increases with the depth, but the regularity is not significant. The ratio of maximum horizontal principal stress to vertical principal stress (Kh,max), the ratio of minimum horizontal principal stress to vertical principal stress (Kh, min) and the ratio of average horizontal stress to vertical principal stress (Kh, av) mainly concentrate in the interval of 1.00 to 2.50, 0.50 to 1.50, and 1.00 to 2.00, respectively. With the increase of depth, the variation amplitudes of the three lateral pressure coefficients decrease gradually: Kh, max, Kh, min and Kh, av tend to 1.83, 0.80 and 1.31, respectively. The ratio of maximum horizontal principal stress to minimum horizontal principal stress has no obvious regularity with the depth, and the values mainly concentrate from 1.5 to 2.0, approximate to normal distribution. Metal mining area has the possibility of fault slip when the depth is less than 500 m, and the reverse fault has the possibility of sliding while the strike slip fault is in a relatively stable state when the depth is more than 500 m. © All right reserved.

Loading State Key Laboratory of the Education Ministry for High Efficient Mining and Safety of Metal Mines collaborators
Loading State Key Laboratory of the Education Ministry for High Efficient Mining and Safety of Metal Mines collaborators