Advanced Materials Research Vols. 524-527

Abstract: During the mining process of shallow buried long wall working face, the breaking of main roof easily result in fracture belt’s connectivity with the surface. The paper has studied the causation of roof cutting and support crushing in shallow-buried large mining height long wall working face of Suancigou coal mine which is in Ordos Inner Mongolia. The main reasons are as follow, poor effect of forced roof caving; unreasonable structure type of support; lower setting load; unevenly stressing between front and rear columns; low advancing speed or the working face. So in order to avoid the fully mechanized supports crushing accident, the working face advancing speed should be accelerated during the period of the pressure change of working face.

Abstract: In order to solve the problem of heaping waste in aboveground, a cleanly mining technique of waste not discharged from coal mine was proposed. It includes two key points as follows: one is waste separation underground; the other is mining technique with preset packing body of waste without coal pillars. After the waste from the coal mining face had been separated out, the waste was used to preset packing body of waste. It is able to decrease stress of mine hoisting. The technique has been successfully used in Gaozhuang Coal Mine.

Abstract: That injecting carbon dioxide into the shale layer below 500 m to extract the shale oil is a method of oil shale exploitation that integrating environmentally friendly energy production and greenhouse gases sequestration. It has been shown by ground test that it is thermodynamically possible to extract shale oil with supercritical carbon dioxide (SCD). However, the prospect of ground extraction is influenced by low extraction rate and difficulty to extract the large molecules. It is fairly feasible if extraction by injection in situ together with the addition of surfactant such as APG for it doesn’t involved with factory building and power consumption. Several questions about the research situation of shale oil extraction and the problems to be researched about shale oil extraction with SCD have been discussed in the paper.

Abstract: Abstract:the domestic and foreign explosive workers who have carried on the massive research work on compression resistance performance of explosives, developed a series of experimental equipment which mostly limits to the qualitative study stage. Through design proposal optimization, explosion temperature，heat of the explosion theoretical calculation as well as the experimental equipment various parts parameter computations, the stress examination had determined finally quite reasonable parameters. This paper eventually developed a set of device which are reusable, less consumable, easy operation. The practice identified the method is an effective to test compression resistance of explosive.

Abstract: Study on compression resistance of emulsion explosives can provide a theoretical basis for underwater blasting and deep-hole basting and development of emulsion explosives. Environment of deep water charge is simulated by a change of pressure of the micro-explosive device .The micro-explosive device was put in the reserved drill hole of mortar test block and applied rating pressure to explode, through fractal theory G-G-S lumpiness distribution function, which was used to date processing to study the fallen extent of explosion capability of emulsion explosives under hydrostatic pressure. The practice has shown that this is an effective new experimental method to study the fallen extent of explosion capability of emulsion explosives under hydrostatic through blasting effects.

Abstract: The Mode I fracture toughness (K_IC) and the Crack Tip Opening Displacement(CTOD) of rock at high temperature are measured by three-point bending test. The K_IC is increased with the increase of temperature and decreased when the temperature reached its critical value (200°C). The internal structure of rock be changed as the temperature increasing and the other mechanical properties of rock, such as tensile strength, compressive strength, elastic modulus, etc. also show the same law with the K_IC which lead the tensile stress hard to reach its critical value. The CTOD increases with the increasing of temperature until the load reach the peak load and the specimens at different temperatures have the same rule.

Abstract: By using of concentration sensors on the premixed tower, the stratification phenomenon of methane has been observed; the change rule of methane concentration at different heights of premixed tower has been analyzed. The results show that, the relation between the time that methane concentration began to be stable and the height of methane in premixed tower shows linear function: T=T₀+Ah; the relation between the stable methane concentration and the height of methane in premixed tower shows exponential function: C=C₀(1-e^Ah) .Based on this, a simple, economic and safe method of separating and purifying methane in coal-bed gas has been proposed.

Abstract: A uranium mill tailings, located in Guangdong, was selected for spatial distribution of the radon exhalation rates measured by local static method. The two-dimension surface of radon exhalation rates was established by Surfer using the data of spatial distribution of radon exhalation rates measured at August 14, 2007 to 19 and 21, which was analyzed by fractal method of projective covering. The results show that the two-dimension surface of radon exhalation rates is of fractal structure. The fractal dimension of surface of radon exhalation rates from August 14, 2007 to 19 and 21 are 2.0535, 2.0173, 2.0029, 2.0084, 2.0079, 2.0057 and 2.0034, respectively, which indicates that the complexity of spatial distribution of the radon exhalation rates at 14 and 15 are larger than that of the other days. The phenomenon results from the change of precipitation and temperature, as well as the features of uranium mill tailings, including mineral composition, particle size, radium content, porosity and pore connectivity, etc.

Abstract: Geo-stress is very important parameters for the design and construction in many underground excavations. The geo-stress of Xieqiao coal mine of Huainan Coal Mining Group is measured by bore-hole stress gauge. The characteristics of stress distribution are discussed. The results show that, in this mine the horizontal stress is in the dominating position and it is bigger than vertical stress.

Abstract: Although many types of curve fitting methods were used in ground settlement prediction, it is due to every prediction method was not perfect, they have some defects and shortcomings to some extent and ground settlement prediction be up against huge challenge. Usher model, being used for economic and resources prediction, is introduced to ground settlement prediction as a new method, and its mathematics features are also analyzed. After comparative analysis, Origin software is selected for parameters solution of Usher model with an explanation of the solving process. Based on the Shipogou tunnel project which through the mined-out regions in Qingdao-Yinchuan highway, the Usher model for ground settlement is established combining to the field data, of which the parameters are solved with the user-defined function and nonlinear tool of Origin. The predicting results being compared with that of grey model and hyperbolic model, it shows that Usher model is of good adaptability, high accuracy, simple and coinciding well with measured data.