UPVC三层复合芯层发泡瓦板的应用

UPVC三层复合芯层发泡瓦板是在中国及54个国家和地区注册了专利的一种新型屋面瓦体系,90年代中期先后在东南亚一些国家应用;90年代末,因为国内的轻型建筑及民用建筑的坡屋面的兴起,在国内生产并得到了推广.在国外,由于是GRAND STAR公司用专利技术独家生产,人们习惯称其为G.STILT.在国内应用后,延用了国外的名称,并汉化为吉爱思瓦或大星瓦,以此来区别单层的PVC瓦、金属瓦、混凝土瓦等材质的瓦,成为UPVC三层复合芯层发泡瓦板的代用简称.

Fracture evolution and pressure relief gas drainage from distant protected coal seams under an extremely thick key stratum

When an extremely thick rock bed exists above a protected coal seam in the bending zone given the condition of a mining protective seam, this extremely thick rock bed controls the movement of the entire overlying stratum. This extremely thick rock bed, called a ＂main key stratum＂, will not subside nor break for a long time, causing lower fractures and bed separations not to close and gas can migrate to the bed separation areas along the fractures. These bed separations become gas enrichment areas. By analyzing the rule of fracture evolution and gas migration under the main key stratum after the deep protective coal seam has been mined, we propose a new gas drainage method which uses bore holes, drilled through rock and coal seams at great depths for draining pressure relief gas. In this method, the bores are located at a high level suction roadway （we can also drill them in the drilling field located high in an air gateway）. Given the practice in the Haizi mine, the gas drainage rate can reach 73% in the middie coal group, with a gas drainage radius over 100 m.

Application of deep borehole blasting on fully mechanized hard top-coal pre-splitting and gas extraction in the special thick seam

In order to solve the problems of top-coal inadequate destruction and large amounts of gas emission in mining extra thick and hard coal seam,this study investigated the pre-splitting for deep borehole blasting and gas pre-draining technologies on top coal.The mechanism of the technologies was systematically expounded based on hard top-coal cracks development obtained by numerical simulation and theoretical analysis.The results show that explosive blasting in the hard rock results in a large number of cracks and large displacement in the rock mass due to the effect of explosion stress.Meanwhile,the thick top-coal caves,and desorbing gas flows along the cracks improve gas extraction.Finally,the pre-splitting for deep borehole blasting and gas pre-draining technologies was applied in No.3802 working face of Shui Liandong Coal Mine,which increases monthly output in the face to 67.34 kt and the drained gas concentration to 86.2%.The drained gas average concentration from each borehole reaches 40%,and the effect is remarkable.

Research into comprehensive gas extraction technology of single coal seams with low permeability in the Jiaozuo coal mining area

For a low permeability single coal seam prone to gas outbursts, pre-drainage of gas is difficult and inefficient, seriously restricting the safety and efficiency of production. Radical measures of increasing gas extraction efficiency are pressure relief and infrared antireflection. We have analyzed the effect of mining conditions and the regularity of mine pressure distribution in front of the working face of a major coal mine of the Jiaozuo Industrial （Group） Co. as our test area, studied the width of the depressurization zone in slice mining and analyzed gas efficiency and fast drainage in the advanced stress relaxation zone. On that basis, we further investigated and practiced the exploitation technology of shallow drilling, fan dril- ling and grid shape drilling at the working face. Practice and our results show that the stress relaxation zone is the ideal region for quick and efficient extraction of gas. By means of an integrated extraction technology, the amount of gas emitted into the zone was greatly reduced, while the risk of dangerous outbursts of coal and gas was lowered markedly. This exploration provides a new way to control for gas in working faces of coal mines with low permeability and risk of gas outbursts of single coal seams in the Jiaozuo mining area.

Theory and application of infrared surveying gas gushing technology in coal-rock roadway

Geological structure and gas expansion when gas pressure was released can affect the distribution of infrared radiation energy or temperature at coal rock surface. From this, the foundation of roadway infrared surveying technical was formed. According to the thermodynamic principle of ideal gas and the law of energy conservation, the relation was established between gas gushing amount from coal rock and air temperature to fall in roadway. At the same time, this paper has analyzed coal rock density change that geological structure aroused and the change exerted influences on infrared radiation power at surface, as well as, has analyzed the infrared radiation feature of gas gushing at geological structure district. Application results show that infrared survey technology can be used to analyze and forecast the change of coal rock gas gushing effectively, and to guide the enforcement of the roadway gas project of prevention and handling economically.

Test studies of gas flow in rock and coal surrounding a mined coal seam

An analysis of the variation rule of abutment pressure at the mining working face in a single coal seam and the mechanical behavior of surrounding rock during stoping is presented. Consideration of the elastic and plastic deformation zones that develop during the mining process allowed the determination of a relationship between horizontal stress and vertical stress. Based on this, a confined pressure unloading test was conducted by the use of the ＂gas-containing coal tbermo-fluid-solid coupling 3-axis servo seep- age＂ experimental apparatus. Thus, gas flow patterns in the elastic and plastic zones were derived from an experimental point of view. Darcy＇s law and the Klinkenberg effect were used to derive a gas flow equation for the elastic and plastic stress fields. The study of gas flow phenomena at the working face during coal mining is of great importance for the study of gas migration and enrichment patterns.