井筒过煤层施工防治煤与瓦斯突出

煤与瓦斯突出是一种复杂的矿井瓦斯动力现象 ,是一种矿井灾害。文中针对顾桥矿井建设现场的实际生产条件 ,介绍了顾桥矿建井期间主井顺利通过 17煤预防煤与瓦斯突出所采取的措施 。

锚杆支护技术在巷道过煤层施工中的应用

祁东煤矿为煤层群开采,各采区主要巷道采取联合布置,因此岩巷施工过程中经常存在揭、过煤层现象。在揭、过煤层施工期间采用U29型棚刚性被动支护不仅施工进度慢,支护费用高,而且巷道压力大,应力集中,支护困难,往往造成巷道前掘后修或多次翻修的局面,给安全生产带来了严重的威胁。针对这一难题,我们进行巷道过煤层期间采用锚杆支护技术的可行性研究并取得成功。

白杨林隧道瓦斯突出预测与过煤层施工技术研究

白杨林隧道工程为煤系地层高瓦斯隧道,设计图提示隧道穿越两道50 cm以上厚度煤层与煤线,施工安全风险等级Ⅰ级。为此,对煤层结构特性及其与隧道空间位置开展了探测研究,对煤与瓦斯的突出风险进行了预测,并制定了防突措施与效果验证,在工作面煤层突出危险解除后,根据煤层与隧道空间关系,结合隧道施工安全步距要求,制定了石门局部揭穿煤层,半煤半岩过煤层采用管棚超前支护等技术措施。结合该项目的工程实践,对《铁路瓦斯隧道技术规范》、《煤矿安全规范》规定进行了讨论。

人工深挖孔桩在铁路桥梁过煤层中的应用

随着我国经济的发展,结合现有条件,人工深挖孔桩因其经济、单桩承载力高等优点,人工深挖孔桩近十年来已得到广泛的采用,但往往由于设计,施工人员对复杂地基比如过煤层基础的认识不足,或处理这类地基的经验较少,容易造成地基承我力不够或浪费。针对此问题,本文从内昆铁路二道桥抢险工程实例出发.论述了施工安全及复杂地基的处理方法。

威尔浮化学浆加固法在祁东煤矿过9煤层中的应用

本文介绍了祁东煤矿采用注化学浆加固法揭过松软突出煤层的成功经验,对类似条件下过煤层、过断层具有一定的借鉴作用。

龙门煤矿井筒掘砌过三软煤层支护方法

管缝式锚杆可以在煤体中以最短的时间发挥最大的锚固力及时对松散煤体进行支护。

水力切割瓦斯增透技术在夹岩水利枢纽工程中的应用

针对夹岩水利枢纽工程水工隧洞过煤层与瓦斯突出问题,应用水力增透技术及高压水射流钻割一体化煤层增透设备进行瓦斯抽放效果分析,研究过煤层瓦斯抽采效率。研究与实践表明:超高压水力切割煤层增透技术适用于硬煤层,且最佳切割压力为75~80 MPa;实测切割钻孔抽采44 d内的单钻孔瓦斯,抽采总量最高达4090.15 m3,是未切割原始钻孔相同时间内抽采总量的2.51~11.47倍,减少了瓦斯抽放时间,并提高了抽放效率。

浅析不同地质构造的岩层中施工巷道的支护方法

在不同地质构造的岩层中施工巷道,应选择不同的支护方法。

Model of coupled gas flow and deformation process in heterogeneous coal seams and its application

The heterogeneity of coal was studied by mechanical tests. Probability plots of experimental data show that the mechanical parameters of heterogeneous coal follow a Weibull distribution. Based on elasto-plastic mechanics and gas dynamics, the model of coupled gas flow＇ and deformation process of heterogeneous coal was presented and the effects of heterogeneity of coal on gas flow and failure of coal wcrc investigated. Major findings include： The effect of the heterogeneity of coal on gas flow and mechanical thilure of coal can be considered by the model in this paper. Failure of coal has a great effect on gas flow.

Technique and experiment of active direct gas pressure measurement in coal roadway

An active measurement method and its principle was introduced consideringthe low success rate,special difficulty,and long measurement time of the direct gas pressuremeasurement currently used in coal roadways.The technology of drilling,boreholesealing depth,borehole sealing length,sealing control of the measuring process,compensatorycomputation of gas loss quantity and other key techniques were discussed.Finally,based on the latest instrument the authors developed,a series of experiments of directgas pressure measurement in the coal roadways of the Jincheng and Tongchuanmine district,were carried out.The experimental results show that active gas pressuremeasurement technique has advantages as follows:(1) the application scope of direct gaspressure measurement technique is wide and it does not have the restriction of coalhardness,coal seam fissure and other conditions;(2) the measured results are credible,which can be tested by the same gas pressure value acquired from a different borehole inthe same place;(3) the measurement process is convenient and quick,it takes about 2 to3 days to acquire the gas pressure value in a coal seam.

Prediction of methane emissions during the extraction of close-to-roof layer of a seam of large thickness

Prediction of methane emissions at the stage of longwall planning constitutes the basis for the determination of the appropriate method and parameters of ventilation and selection of prevention means including the methane drainage technol- ogy. The growth of methane saturation of coal seams with the extraction depth, with simultaneously increasing output concen- tration, contributes to the increase of the quantity of methane emitted into longwall areas. The subject matter of the article has been directed at the predicted quantity of methane emissions into planned longwalls with roof caving in the layer of seams adjacent to the roof of large thickness. The performed prognostic calculations of methane emissions into the longwall working were referred to two sources, i.e. methane liberated during coal mining by means of a cutter-loader and methane originating from the degasification of the floor layer destressed by the longwall conducted in the close-to-roof layer. The calculations of predictions allow to refer to the planned longwall, on account of the emitting methane, with possible and safe output quantity. Planning of extraction in the close-to-roof layer of a seam of large thickness with roof caving is especially important in con- ditions of increasing methane saturation with the depth of deposition and should be preceded by a prognostic analysis for de- termining the extraction possibilities of the planned longwall.

Mechanism of mine water-inrush through a fault from the floor

The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries.In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone aquifers.Our study describes the mechanism of mine water inrushes through a fault in the mine floor using principles of strata mechanics and the path of water inrush from an aquifer to the working face.A criterion to judge whether a ground water inrush will occur through a fault or not is also described, together with a case history of water inflow in the Feicheng coalfield, China.

Breaking process and mining stress evolution characteristics of a high-position hard and thick stratum

Based on the boundary support conditions of overlying high-position,hard and thick strata,a Winkler foundation beam mechanical model was built.Computational expressions for the characteristics and position of the bending moment for high-position,hard and thick strata were constructed by theoretical analysis,and the initial breaking position of high-position,hard and thick strata was also analyzed.The breaking process and evolution law of mining stress in high-position,hard and thick strata were studied by similar material simulation tests.Studies show that:due to the foundation deformation effect of the lower strata,the initial break position in high-position,hard thick layers is in the middle of goaf;vertical tension fractures first occur under the middle surface,then tilt tension fractures form at both sides and a non-uniform thickness of the fracture structure forms and produces subsidence deformation;behind the coal wall tilt fractures extend and eventually complete the migration.Mining stress produces obvious changes before and after the breakage of the high,hard and thick stratum;high stress concentration forms in front of the coal wall before breakage and fracture stress concentration significantly reduces after migration.Coal seam mining under high-position,hard thick strata can easily induce dynamic phenomena.

Recent Advances in Flame Tomography

To reduce greenhouse gas emissions from fossil fuel fired power plants,a range of new combustion technologies are being developed or refined,including oxy-fuel combustion,co-firing biomass with coal and fluidized bed combustion.Flame characteristics under such combustion conditions are expected to be different from those in normal air fired combustion processes.Quantified flame characteristics such as temperature distribution,oscillation frequency,and ignition volume play an important part in the optimized design and operation of the environmentally friendly power generation systems.However,it is challenging to obtain such flame characteristics particularly through a three-dimensional and non-intrusive means.Various tomography methods have been proposed to visualize and characterize flames,including passive optical tomography,laser based tomography,and electrical tomography.This paper identifies the challenges in flame tomography and reviews existing techniques for the quantitative characterization of flames.Future trends in flame tomography for industrial applications are discussed.

A Pilot-scale Demonstration of Reverse Osmosis Unit for Treatment of Coal-bed Methane Co-produced Water and Its Modeling

This study presents the first demonstration project in China for treatment of coal-bed methane(CBM) co-produced water and recycling.The work aims to provide a research and innovation base for solving the pollution problem of CBM extraction water.The reverse osmosis(RO) unit is applied to the treatment of CBM co-produced water.The results indicate that system operation is stable,the removal efficiency of the total dissolved solids(TDS) is as high as 97.98%,and Fe,Mn,and F-are almost completely removed.There is no suspended solids(SS) detected in the treated water.Furthermore,a model for the RO membrane separation process is developed to describe the quantitative relationship between key physical quantities-membrane length,flow velocity,salt concentration,driving pressure and water recovery rate,and the water recovery restriction equation based on mass balance is developed.This model provides a theoretical support for the RO system design and optimization.The TDS in the CBM co-produced water are removed to meet the "drinking water standards" and "groundwater quality standards" of China and can be used as drinking water,irrigation water,and livestock watering.In addition,the cost for treatment of CBM co-produced water is assessed,and the RO technology is an efficient and cost-effective treatment method to remove pollutants.

Failure modes of coal containing gas and mechanism of gas outbursts

In order to explain the mechanism for gas outburst, the process of evolving fractures in coal seams is described using system dynamics with variable boundaries. We discuss the failure modes of coal containing gas and then established the flow rules after failure. The condition under which states of deformation convert is presented and the manner in which these convert is proposed. In the end, the process of gas outbursts is explained in detail. It shows that a gas outburst is a process in which the boundaries of coal seams are variable because of coal failure. If the fractures are not connected or even closed owing to coal/rock stress, fractured zones will retain a certain level of carrying capacity because of the self-sealing gas pressure. When the accumulation of gas energy reaches its limit, coal seams will become unstable and gas outbursts take place.