浅谈沿海经济开放后的民族山区金融对策

随着我国沿海经济开放区的发展和桂东南经济开放战略的实施,背靠大西南的桂西北民族山区,在沿海经济开放的强大幅射和桂东南开放圈的半包围下,面临着经济和金融形势的严峻挑战。对此,山区金融部门必须认清形势,作出新的金融对策,以帮助山区适应外部各开放层次的冲击,因地制宜地发展民族经济。

立体街区及其实践与研究进展

构建立体城市是响应紧凑化城市建设的重要举措之一。立体街区内涵体现在空间形态、功能结构的立体化等方面,其中,多层开放空间系统是立体街区的关键特征。立体街区实践主要包括商业主导型、地形高差型和交通主导型三种类型。近十年的研究集中在立体街区的空间形态、空间使用、优化设计三个方面,呈现出多线并行的特点,研究尺度相对单一,尤其是缺少针对立体街区三维空间使用规律的研究。需要构建全尺度的立体街区形态分析体系和使用绩效评价体系,以及探索两者的关联规律,为立体街区的精细化规划实践提供系统性研究参考。

步行使用视角下立体商业街区开放空间研究

以立体商业街区多层开放空间为研究对象,结合城市形态学、立体城市、空间句法、环境行为学等理论,基于街区多层开放空间形态、环境与步行使用强度及分布之间的关联分析,探索立体商业街区多层开放空间系统整体的形态呈现体系、绩效评测方法及优化设计策略,为立体街区多层开放空间的建设提供理论、工具及方法借鉴。

软件定义网络(SDN)控制器技术与应用

随着网络技术的不断发展,现有网络封闭式体系结构已严重制约了网络创新。鉴于此,软件定义网络(SDN)技术将网络体系垂直解耦,并开放了控制层及其协议。阐述了SDN技术概念及体系架构,分析了SDN技术特点和关键技术,最后提出了构建新型数据中心系统的设想。

档案工作者要强化社会意识

随着《档案法》普及性的宣传,社会群体的挡案意识日渐提高。相形之下,档案工作者的社会意识就面临着进一步强化的问题了。改革开放层层深入的时代要求,档案工作者必须增强意识,面向社会,面向经济建设的主战场,跟上时代前进的步伐。这样做,反过来又会进一步促进社会群体档案意识的提高。强化档案工作者的社会意识似乎是一个很容易理解的问题。

中国音乐史学的多层开放研究结构与学科建设

新时期历史学研究最为突出的转变,就是研究视角的多向,研究方法的多样,研究领域的扩展。这里从学科理论的认知模式角度,提出的中国音乐史学研究的文献文物层、史实考释层、因果关系层、规律法则层、哲学思辨层这五个分层结构,是一个开放的、也是系统的分层研究结构。在这样的结构中,每一层结构都有其相对独立性和学术价值、评价标准。从学术理性上认识这样一个分层研究结构,有助于了解各类研究的立场、角度和定位。确立这样一个开放的研究结构系统,将有助于形成学科研究的自觉意识。

Simulation Analysis of Coal Mining with Top-Coal Caving Under Hard-and-Thick Strata

The top-coal failing ability is a key factor to analyze for the application of coal mining with top-coal caving. Based on a hard-and-thick strata, which acts both as the floor of the upper coal seam and as the roof of the lower coal seam, nine mining projects wcrc put forward to examine the mining of upper and lower coal seams, and a numerical simulation was used to study in detail the corresponding top-coal compressed volume of the lower coal seam. By the simulation effects of different layouts of coalface, the rational mining method was determined to bc the staggered layout of coalface in the upper and the lower coal seam. This can ensure the successful use of fully-mechanized coalfacc with top--coal caving in the lower coal seam.

Study on first caving fracture mechanism of overlying roof rock in steep thick coal seam

Based on the elastic plate theory, a mechanical model of thin plate for the first caving of overlying roof rock in steep mining face was established. The analytical solution of the deflection and stress distribution of roof rocks was obtained. According to the specific geological conditions of the 5-103 panel in Shanxi,the failure of roof rocks and the influence of seam dip on it during the exploitation were theoretically investigated. Meanwhile, the first caving characteristics of the overlying rock in the steep coal seam were investigated based on its stress contour. The results show that the dip angle has a distinct influence on the caving interval and the first caving interval for the 5-103 panel is 37 m in theory. Finally, a systematic monitoring on the behavior of rock pressures was conducted. The measured results agree well with the theoretical prediction, which provides a good reference for practical steep coal seam mining.

Effects of caving–mining ratio on the coal and waste rocks gangue flows and the amount of cyclically caved coal in fully mechanized mining of super-thick coal seams

Aimed at determining the appropriate caving–mining ratio for fully mechanized mining of 20 m thick coal seam, this research investigated the effects of caving–mining ratio on the flow fields of coal and waste rocks, amount of cyclically caved coal and top coal loss by means of numerical modeling. The research was based on the geological conditions of panel 8102 in Tashan coal mine. The results indicated the loose coal and waste rocks formed an elliptical zone around the drawpoint. The ellipse enlarged with decreasing caving–mining ratio. And its long axis inclined to the gob gradually became vertical and facilitating the caving and recovery of top coal. The top coal loss showed a cyclical variation; and the loss cycle was shortened with the decreasing in caving–mining ratio. Moreover, the mean squared error(MSE) of the amount of cyclically caved coal went up with increasing caving–mining ratio, indicating a growing imbalance of amount of cyclically caved coal, which could impede the coordinated mining and caving operations. Finally it was found that a caving–mining ratio of 1:2.51 should be reasonable for the conditions.

Characteristics of ground behavior of fully mechanized caving faces in hard thick seams

It is showed in practice that the support load and its fluctuation is large, the periodic weighting is obvious and can be divided into two kinds, the large and small pressure, sometimes the behavior of the large pressure is very violent in hard thick seam caving faces. These are obviously different from those of the generally soft or medium hard seam caving feces. All above these are summarized, and the causes aroused these are researched. Finally the powered support selection of hard thick seam caving faces is discussed.

Arch structure effect of the coal gangue flow of the fully mechanized caving in special thick coal seam and its impact on the loss of top coal

Based on the characteristics of the top coal thickness of the fully mechanized caving in special thick coal seam,the long distance of coal gangue caving,as well as the different sizes of the coal gangue broken fragment dimension and spatial variation of drop flow,this paper uses laboratory dispersion simulation experiment and theoretical analysis to study the arch structure effect and its influence rule on the top coal loss in the process of coal gangue flow.Research shows that in the process of coal gangue flow,arch structure can be formed in three types:the lower arch structure,middle arch structure,and upper arch structure.Moreover,the arch structure has the characteristics of dynamic random arch,the formation probability of dynamic random arch with different layers is not the same,dynamic random arch caused the reduction of the top coal fluency;analyzing the dynamic random arch formation mechanism,influencing factors,and the conditions of instability;the formation probability of the lower arch structure is the highest,the whole coal arch and the coal gangue arch structure has the greatest impact on top coal loss.Therefore,to prevent or reduce the formation of lower whole coal arch structure,the lower coal gangue arch structure and the middle whole coal arch structure is the key to reduce the top coal loss.The research conclusion provides theoretical basis for the further improvement of the top coal recovery rate of the fully mechanized caving in extra thick coal seam.

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.

Green coal mining technique integrating mining-dressing-gas draining-backfilling-mining

Aiming to address the following major engineering issues faced by the Pingdingshan No. 12 mine:(1) difficulty in implementing auxiliary lifting because of its depth(i.e., beyond 1000 m);(2) highly gassy main coal seam with low permeability;(3) unstable overlying coal seam without suitable conditions for implementing conventional mining techniques for protective coal seam; and(4) predominant reliance on ‘‘under three" coal resources to ensure production output. This study proposes an integrated, closed-cycle mining-dressing-gas draining-backfilling-mining(MDGBM) technique. The proposed approach involves the mining of protective coal seam, underground dressing of coal and gangue(UDCG), pressure relief and gas drainage before extraction, and backfilling and mining of the protected coal seam. A system for draining gas and mining the protective seam in the rock stratum is designed and implemented based on the geological conditions. This system helps in realizing pressure relief and gas drainage from the protective seam before extraction. Accordingly, another system, which is connected to the existing production system, is established for the UDCG based on the dense medium-shallow trough process. The mixed mining workface is designed to accommodate both solid backfill and conventional fully mechanized coal mining, thereby facilitating coal mining, USCG, and backfilling. The results show that: The mixed mining workface length for the Ji15-31010 protected seam was 220 m with coal production capacity 1.2 million tons per year, while the backfill capacity of gangue was 0.5 million tons per year. The gas pressure decreased from 1.78 to 0.35 MPa, and the total amount of safely mined coal was 1.34 million tons. The process of simultaneously exploiting coal and draining gas was found to be safe, efficient, and green.This process also yielded significant economic benefits.

The control of coal mine gas and coordinated exploitation of coal bed methane in China

Based on the characteristics of the coalfield geology and the distribution of coalbed methane (CBM) in China,the geological conditions for exploiting the CBM and drainingthe coal mine gas were analyzed,as well as the characteristics of CBM production.Bycomparing the current situation of CBM exploitation in China with that in the United States,the current technology and characteristics of the CBM exploitation in China were summarizedand the major technical problems of coal mine gas control and CBM exploitationanalyzed.It was emphasized that the CBM exploitation in China should adopt the coalmine gas drainage method coordinated with coal mine exploitation as the main model.Itwas proposed that coal mine gas control should be coordinated with coal mine gas exploitation.The technical countermeasure should be integrating the exploitation of coal andCBM and draining gas before coal mining.

Research on New Method of Full-Seam Mining for Gently Inclined Thick Coal Seams

The recovery ratio of top coal caving mining plays a key role in the development of this mining method. For the proposes to raise the recovery ratio and considering heading advance and roadway maintenance, a new method of full seam mining for gently inclined thick coal seams is put forward on the basis of a theoretic research and engineering practice.

Greenhouse gas emissions from shallow uncovered coal seams

This study discusses a method of quantifying emissions from surface coal mining that has been trialled in Australia. The method is based on direct measurement of surface emissions from uncovered coal seams in mine pits, concurrent measurement of residual gas content of blasted coal in mine pits, and measurement of pre-mining gas content of the same seam from cores retrieved from exploration boreholes drilled away from active mining. The results from one of the mines studied are presented in this paper. In this mine,the pre-mining gas content of the target seam was measured using cores from an exploration borehole away from active mining. Gas content varied from 0.7 to 0.8 m3/t and gas composition varied from16% to 21% CH4(84–79% CO2). In-pit measurements included seam surface emissions and residual gas content of blasted and ripped coal. Residual gas content varied from 0.09 to 0.15 m3/t, less than twofold across the mine pit. Composition of the residual gas was in general 90% CO2and 10% CH4, with slight variation between samples. Coal seam surface emissions varied from 1.03 to 7.50 mL of CO2-e per minute and per square meter of the coal seam surface, a sevenfold variation across the mine pit.

Some parameters of coal methane system that cause very slow release of methane from virgin coal beds(CBM)

In some worldwide hard coal basins recovery of methane from virgin coal beds is difficult. In general,mentioned difficulties are related to geo-mechanical, petrographical and physical-chemical properties of coals in question, occurring for example in the Bowen Basin(Australia) or the Upper Silesian Coal Basin(Poland). Among numerous properties and parameters, the following are very essential: susceptibility of coal beds to deformation connected with coal stress state change and contemporary shrinkage of the coal matrix during methane desorption. Those adverse geo-mechanical and physical-chemical effects are accompanied by essential change of the porous coal structure, which under these disadvantageous conditions is very complex. This study aims to show difficulties, which occur in phase of recognition of the methane-reach coal deposit. Volume absorbed methane(not surface adsorbed) in sub-micropores having minimal size comparable with gas molecule diameter must possess energy allowing separation of the nodes and methane release to micropores.

Key technologies and equipment for a fully mechanized top-coal caving operation with a large mining height at ultra-thick coal seams

Thick and ultra-thick coal seams are main coal seams for high production rate and high efficiency in Chinese coal mines, which accounts for 44 % of the total minable coal reserve. A fully mechanized top-coal caving mining method is a main underground coal extraction method for ultra-thick coal seams. The coal extraction technologies for coal seams less than 14 m thick were extensively used in China. However, for coal seams with thickness greater than 14 m, there have been no reported cases in the world for underground mechanical extraction with safe performance, high efficiency and high coal recovery ratio. To deal with this case, China Coal Technology ＆ Engineering Group, Datong Coal Mine Group, and other 15 organizations in China launched a fundamental and big project to develop coal mining technologies and equipment for coal seams with thicknesses greater than 14 m. After the completion of the project, a coal extraction method was developed for top-coal caving with a large mining height, as well as a ground control theory for ultra-thick coal seams. In addition, the mining technology for top-coal caving with a large mining height, the ground support technology for roadway in coal seams with a large cross-section, and the prevention and control technology for gas and fire hazards were developed and applied. Furthermore, a hydraulic support with a mining height of 5.2 m, a shearer with high reliability, and auxiliary equipment were developed and manufactured. Practical implication on the technologies and equipment developed was successfully completed at the No. 8105 coal face in the Tashan coal mine, Datong, China. The major achievements of the project are summarized as follows： 1. A top-coal caving method for ultra-thick coal seams is proposed with a cutting height of 5 m and a top-coal caving height of 15 m. A structural mechanical model of overlying strata called cantilever beam-articulated rock beam is established. Based on the model, the load resistance of the hydraulic support with a large mining height for top-coal caving method is determined. With the analysis, the movement characteristics of the top coal and above strata are evaluated during top-coal caving operation at the coal face with a large mining height. Furthermore, there is successful development of comprehensive technologies for preventing and controlling spalling of the coal wall, and the top-coal caving technology with high efficiency and high recovery at the top-coal caving face with a large mining height. This means that the technologies developed have overcome the difficulties in strata control, top-coal caving with high efficiency and high coal recovery, and enabled to achieve a production rate of more than 10 Mtpa at a single top-coal caving face with a large mining height in ultra-thick coal seams; 2. A hydraulic support with 5.2 m supporting height and anti-rockburst capacity, a shearer with high reliability, a scraper conveyor with a large power at the back of face, and a large load and long distance headgate belt conveyor have been successfully developed for a top-coal caving face with large mining height. The study has developed the key technologies for improving the reliability of equipment at the coal face and has overcome the challenges in equipping the top-coal caving face with a large mining height in ultra-thick coal seams; 3. The deformation characteristics of a large cross-section roadway in ultra-thick coal seams are discovered. Based on the findings above, a series of bolt materials with a high yielding strength of 500-830 MPa and a high extension ratio, and cable bolt material with a 1 × 19 structure, large tonnage and high extension ratio are developed. In addition, in order to achieve a safe roadway and a fast face advance, installation equipment for high pre-tension bolt is developed to solve the problems with the support of roadway in coal seams for top-coal caving operation with a large mining height; 4. The characteristics of gas distribution and uneven emission at top-coal caving face with large mining height in ultra-thick coal seams are evaluated. With the application of the technologies of gas drainage in the roof, the difficulties in gas control for high intensive top-coal caving mining operations, known as ＂low gas content, high gas emission＂, are solved. In addition, large flow-rate underground mobile equipment for making nitrogen are developed to solve the problems with fire prevention and safe mining at a top-coal caving face with large mining height and production rate of more than 10 Mtpa. A case study to apply the developed technologies has been conducted at the No. 8105 face, the Tashan coal mine in Datong, China. The case study demonstrates that the three units of equipment, i.e., the support, shearer and scraper conveyor, are rationally equipped. Average equipment usage at the coal face is 92.1%. The coal recovery ratio at the coal face is up to 88.9 %. In 2011, the coal production at the No. 8105 face reached 10.849 Mtpa, exceeding the target of 10 Mtpa for a topcoal caving operation with large mining height performed by Chinese-made mining equipment. The technologies and equipment developed provide a way for extracting ultra-thick coal seams. Currently, the technologies and equipment are used in 13 mining areas in China including Datong, Pingshuo, Shendong and Xinjiang. With the exploitation of coal resources in Western China, there is great potential for the application of the technologies and equipment developed.

Top coal flows in an excavation disturbed zone of high section top coal caving of an extremely steep and thick seam

Compared with gentle dip long-wall caving,the length of a working face in fully-mechanized top-coal caving for extremely steep and thick seams is short,while its horizontal section is high with increasing production.But the caving ratio is low,which might result in some disasters,such as roof falls,induced by local and large area collapse of the top coal in a working face and dangers induced by gas accumulation. After the development of cracks and weakening of the coal body,the tall,broken section of the top coal（a granular medium）of an extremely steep seam（over 60°）shows clear characteristics of nonlinear movement.We have thoroughly analyzed the geological environment and mining conditions of an excavation disturbed zone.Based on the results from a physical experiment of large-scale 3D modeling and coupling simulation of top coal-water-gas,we conclude that the weakened top coal can be regarded as a non-continuous medium.We used a particle flow code program to compare and analyze migration processes and the movements of a 30 m high section top coal over time before and after weakening of an extremely steep seam in the Weihuliang coal mine.The results of our simulation, experiment and monitoring show that pre-injection of water and pre-splitting blasting improve caving ability and symmetrical caving,relieve space for large area dynamic collapse of top coal,prolong migration time of noxious gases and release them from the mined out area and so achieve safety in mining.