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Based on tensile test of rebar bolt and deformation feature in deep rock，constitutive models of bolt after installation and laneway's side rupture zone，plastic zone and elastic zone were established，and the ordinary bolt parameters' effect on constitutive model of laneway's side was analyzed. The results indicate the bolt can control the deformation in rupture zone and plastic zone，and the anchorage strength can be maintained，when the anchoring section of the bolt is located in elastic zone. For the deformation roadway，the bolt was too short in length，the cable had low elongation，and support material lose effectiveness after the rib spalling and enlarging. Therefore，a new long-thread lengthened bolt was invented，which had the feature of “deep anchorage point”，“good extension” and “multiple reuse”，and the long-rigid-thread section could avoid the waste of bolt and cable after the rib spalling and enlarging in roadway. [ABSTRACT FROM AUTHOR]

Experimental tests about the crack propagation of coal specimens having a central borehole under local load were conducted with high definition video camera，infrared thermal imaging instrument and relevant software. The characteristics in the whole process of crack initiation，propagation，coalescence under different local loads were analyzed. The results showed that the crack propagation in the specimens was caused by the coupling effect of load conditions and macro center borehole，and the route of crack was also dominated by it. However，the anisotropism rooted in micro pores played a subordinate role. It would cause tensile or shear stress area around the borehole under uniform load，which was a key factor for crack propagation on that conditions. Macro center borehole was the main factor to cause stress concentration，but the dominate position of it would subvert with the change of load area，and the sequence of stress concentration occurred suddenly，the position of crack initiation was turned from peripheral borehole to the critical point of the load. The influence of load area on the crack propagation in the specimens having a central borehole had a regional characteristic，which occurred obviously in the region of load area. With local load increase，the scale of the initial crack(crack width and length) increase，and the crack direction showed the trend of non straight. [ABSTRACT FROM AUTHOR]

In order to study the particle size of the pulverized coal that bring trouble to pump and reduce pump accident. The size analysis of drilling cuttings finds that the fines less than 0. 0374 mm and more than 3. 8 mm are the main particle for stuck pump,plug pump or plug shaft. Further study narrows the size range by means of LPSA(Laser Particle Size Analyzer). In the static settling velocities experiment,it is found that when the concentration of fines is very low,settlement velocity decreases with the increase of concentration. When the concentration is increased,coal settlement rate will no longer change and tend to a constant value. It is also found that the lower of concentration of fines,the higher of coal suspension rate. In the wetting experiments of different pulverized coal samples,it is found that the wettability of fine sample of the drilling cuttings is poorer than that of sample of output of drainage,but the wetting modification effect of fine sample of the drilling cuttings is better. According to the experimental results,the basic physical characteristics of fines are summarized in order to guide the production of fines in the coalbed methane well. [ABSTRACT FROM AUTHOR]

During the excavation of coal roadway，the surrounding rock often shows abnormal and large elastic deformation. This behavior is difficult to explain with Hooke’s law. This indicates that even in the elastic deformation stage，the coal also show a strong nonlinear behavior. Compared with other rocks，since the distribution of various defects，such as pore，fracture，bedding and cleats，coal has more obvious heterogeneity. Firstly，the nonlinear elastic characteristics of coal are analyzed in this paper.Then it gives the constitutive equation of the nonlinear elastic mechanical behavior and the numerical programming. NLEPS constitutive model is proposed considering the nonlinear elastic mechanical behavior of coal. Finally，the effective numerical verification is carried out，and the application feasibility analysis is carried out in coal roadway excavation. The calculation results indicate that the nonlinear deformation behavior of surrounding rock which is induced by coal roadway excavation is more accurately reflected by the calculation results based on NLEPS constitutive model. The nonlinear elastic constitutive model parameter has a clear physical meaning and can be widely used in coal mining engineering. [ABSTRACT FROM AUTHOR]

The coal mine dust induced an increasing coal miner's pneumoconiosis and serious coal dust explosion. However, the existing wet dust collection technologies are generally inefficient. According to the environmental conditions of fully-mechanized excavation face in coal mine, the main influencing factors of dry-type filtering dust collection technology in fully-mechanized excavation face are water spraying in the air, uniformity of cleaning and cleaning strategy, etc. Therefore, dry-type filtering dust collection experiment system and prototype are built in this study. An experimental study shows that a moderate amount of spray (2 200 mL/min) is beneficial to improve the filtration performance of the dust collection system. The installation of the normal cone and column cone in the filter cartridge can improve the injection flow field. The positive and reverse cleaning mode is more conducive to improve the cleaning effect and reduce the dust emission concentration respectively. A dry-type filtration dust collector KCG-200D is developed and applied in the Gequan coal mine. The total and respirable dust collection efficiencies are 97.39% and 96.41% at the scene. [ABSTRACT FROM AUTHOR]

The genetic type of microscopic pore，the characteristics of pore structure and its influence on gas content from the Lower Cambrian Qiongzhusi and Lower Silurian Longmaxi Formations shale gas reservoirs in southern Sichuan Basin were studied by using scanning electron microscope，argon ion polishing-field emission scanning electron microscope，Image J2x software analysis，high pressure mercury injection，low temperature N2 and CO2 adsorption experiments. The results show that the multiple genetic types of microscopic pores，including inter-granular pore，intragranular pore，organic matter pore and microcrack，are developed in the Lower Paleozoic shale in southern Sichuan Basin. The total surface porosity of microscopic pores is ranged from 3.95% to 7.48%. The total surface porosity and organic pore surface porosity of the Qiongzhusi Formation shale are lower than those of the Longmaxi Formation shale.The total pore volume of the Lower Paleozoic shale is (3.93-24.96)×10-3mL/g，total specific surface area is 2.727-29.399 m2/g in range.These pores whose pore sizes are 0.35-1.00，2.5-4.7 and 55-75 nm in range are the main contribution of total pore volume，and those pores whose pore sizes are 0.3-1.0 nm and 2.5-5.5 nm in range account for the main total specific surface area.Total pore volume and total specific surface area of the Qiongzhusi Formation shale are lower than those of the Longmaxi Formation shale.All the surface porosity，organic pore，pore volume，specific surface area and pore size distribution of microscopic pores will affect the gas content of shale.The above differences of pore structure characteristics in the Lower Paleozoic Qiongzhusi and Longmaxi Formations shale provide a basis for revealing the difference of gas content between the Qiongzhusi Formation shale and the Longmaxi Formation shale in southern Sichuan Basin. [ABSTRACT FROM AUTHOR]