Lateral abutment pressure distribution and evolution in wide pillars under the first mining effect

The wide pillars are generally popular due to the high productivity and efficiency in Northwest China. The distribution of lateral abutment pressure in coal pillars is important for mining safety. To reveal the effect of the first mining on the lateral abutment pressure distribution and evolution in wide pillars, an in-situ experiment, theoretical analysis and numerical simulation were performed. First, the field monitoring of lateral abutment pressure was conducted from the perspective of time ...     

Effect of atomization gas pressure variation on gas flow field in supersonic gas atomization

In this paper, a computational fluid flow model was adopted to investigate the effect of varying atomization gas pressure (P0) on the gas flow field in supersonic gas atomization. The influence of P0 on static pressure and velocity magnitude of the central axis of the flow field was also examined. The numerical results indicate that the maximum gas velocity within the gas field increases with increasing P0. The aspiration pressure (ΔP) is found to decrease as P0 increases at a lower atomization gas pressure...     

关于可压缩气体等断面管路流动的探讨

通过理论分析与计算,探讨了可压缩气体等断面管路流动的规律,为工程技术人员在设计与计算中应用管路流动方程给出了合理的说明与明确的适用范围.     

产于可压缩气体等断面管路流动的探讨

通过理论分析与计算,探讨了可压缩气体等断面管路流动的规律,为工程技术人员在设计与计算中应用管路流动方程给出了合理的说明与明确的适用范围。     

Analytical solution to one-dimensional mathematical model of flow and morphological evolution in open channels

Science China Technological Sciences - The evolution of open-channel flow and morphology can be simulated by one-dimensional (ID) mathematical models. These models are typically solved by numerical...     

Distribution of lateral floor abutment pressure in a stope

In order to study the distribution of lateral floor abutment pressure at a working face, we first used elasticity theory to establish a distribution model of lateral floor abutment pressure and then analysed its distribution. Second, we established a three-dimensional numerical simulation model of the Haizi Coal Mine No. 86 mining area by using FLAC3D (ITASCA Consulting Group) software. We investigated the distribution of lateral floor abutment pressure of a stope, which indicated that the position of abutment pressure peak varies at different floor depths. We then determined the rational reinforcement range of a floor roadway, based on the conclusion reached earlier. Finally, we used our conclusions in support of the No. 86 mining area crossing-roadway. The supported crossing-roadway remained stable when mining the upper workface, which validates the accuracy of our numerical simulation and provides a future reference for the support of span-roadways under similar conditions.     

基于微震监测的超前支承压力分布特征研究

为了定量研究煤矿采场超前支承压力的分布规律,采用固定工作面的方法,研究了采煤工作面前方微震事件的分布特征,在此基础上通过微震波波形分析和反演,进行了工作面前方视应力的分布特征研究.结果表明,采用固定工作面能更好的反映超前支承压力与微震监测参数的关系,同实测超前支承压力曲线一样,视应力曲线同样具有明显的单峰值结构,通过分析工作面前方视应力分布曲线可以获得描述超前支承压力分布特征的所有参数.     

Noble gas constraints on hydrocarbon accumulation and groundwater flow in the central area of Western Sichuan Basin

The noble gas concentrations and isotope ratios of seven natural gas samples from the central area of the Western Sichuan Basin were measured. The samples all have 40Ar/36Ar ratios greater than the atmospheric values, and the 3He/4He ratios (R/Ra) are entirely consistent with the crustal radiogenic He values. The vertical variation of the calculated CH4/36Ar ratios with depth clearly indicates that the CH4and 36Ar are intimately associated, indicating a common reservoir intermediate to the sampled reservoirs, where they are well mixed and stored together prior to entrapment into gas reservoirs. Meanwhile, the calculated CH4/36Ar ratios range between 8×106 and 64×106 very much greater than the CH4/36Ar values for pure water and 5 mol/L NaCI brine at low temperature and hydrostatic conditions, reflecting the presence of "excess" thermogenic CH4 over that supplied by a CH4-saturated groundwater at low temperature, and the excess CH4 saturation and dissolution to be at depth greater than the sampled reserv     

Noble gas constraints on hydrocarbon accumulation and groundwater flow in the central area of Western Sichuan Basin

The noble gas concentrations and isotope ratios of seven natural gas samples from the central area of the Western Sichuan Basin were measured. The samples all have⁴⁰Ar/³⁶Ar ratios greater than the atmospheric values, and the³He/⁴He ratios (RIR _a ) are entirely consistent with the crustal radiogenic He values. The vertical variation of the calculated Ch₄/³⁶Ar ratios with depth clearly indicates that the CH₄ and³⁶Ar are intimately associated, indicating a common reservoir intermediate to the sampled reservoirs, where they are well mixed and stored together prior to entrapment into gas reservoirs. Meanwhile, the calculated CH₄/³⁶Ar ratios range between 8×10⁶ and 64×10⁶ very much greater than the CH₄/³⁶Ar values for pure water and 5 mol/L NaCl brine at low temperature and hydrostatic conditions, reflecting the presence of “excess” thermogenic CH₄ over that supplied by a CH₄-saturated groundwater at low temperature, and the excess CH₄ saturation and dissolution to be at depth greater than the sampled reservoirs. This conclusion is consistent with the δ¹³C(CH₄) and δ¹³C(C₂H₆) values. In addition, the⁴He/³⁶Ar ratio is correlated with depth, showing that the crustal radiogenic⁴He are well mixed with the atomosphere-derived³⁶Ar before introducing into gas reservoirs. The⁴He/³⁶Ar ratio vertical variation with depth can be attributed to the preferential transport of⁴He relative to³⁶Ar in fluxes from lower aquifers through water-filled pores into the upper one. The increasing⁴He/⁴⁰Ar ratios with decreasing depth, from 1.3 times to 29 times greater than the crustal production ratio, are also assumed to be the results of preferential transport⁴He relative to⁴⁰Ar from the production site into groundwater.

     

Experimental research into the effect of gas pressure,particle size and nozzle area on initial gas-release energy during gas desorption

Coal and gas outburst is a violent disaster driven by released energy from gas desorption. The initial expansion energy of released gas(IEERG) is a new method to predict coal and gas outburst. In this paper,an instrument for IEERG measurement was developed. Compared with previous setups, the new one which is equipped with three convergent nozzles and quick-release mechanism gets improved in data acquisition and gas sealing and releasing performance. To comprehensively know the effect of gas pressure, particle size, and nozzle area on IEERG, a series of experiments were carried out with this new setup.The variable control test results indicated that the gas pressure-IEERG curves remain the linear trend and the particle size-IEERG curves maintain the negative exponential trend for nozzle areas at 1.13, 2.26, and3.39 mm2, respectively. The increase in nozzle area leads to deceases in value of IEERG and absolute value of slope of fitting curves in each test. In addition, the orthogonal experiment showed that the influence of gas pressure, nozzle area, and particle size on IEERG decreases in turn. Only gas pressure had a marked impact on IEERG. This work offers great importance in improving the accuracy of prediction of coal and gas outburst.     

Numerical investigation on gas flow heat transfer and pressure drop in the shell side of spiral-wound heat exchangers

As a critical facility,spiral-wound heat exchanger was(SWHE)has the been widely used in many industrial applications.boundary A computational fluid dynamics(CFD)model employed with smallest periodic element results and periodic conditions to examine around the the characteristics tube of the shell side of SWHE.Numerical simulation show that the heat transfer coefficients and initially mean increase absolute and subsequently decrease simulated 5%with heat radial angle because of the influence measured of backflow turbulent separation.nitrogen The deviation between is transfer coefficients and values for methane,drop,ethane,and are a mixture(methane/ethane)within when mean Reynolds number is over is 30000.For the pressure the simulated results values smaller than the measured values,and the absolute on deviation within 9%.Numerical simulation also tubes indicate that the pressure drop the and heat of transfer coefficients angle the shell side and of SWHE heat decrease as the winding the angle of the increases.Nusselt Considering effect winding on pressure drops transfer coefficients,modified correlations of_=0.308Re~(0.64)Pr~(0.36)(1+sin)~(1.38 )and friction factor f_=0.435Re~(-0.133)(sin)~(-0.36),are proposed.Comparing Nu number with the experimental data,the maximum deviations for heat transfer coefficients and pressure drops are less than 5%and11%respectively.     

焦作云台山与青龙峡景区中奥陶统马家沟组沉积特征及演化规律

通过对焦作云台山与青龙峡景区中奥陶统马家沟组的岩性、沉积构造、古生物实体化石和遗迹化石的组成和分布特征分析及其沉积环境研究,结果表明,研究区马家沟组主要为潮坪-碳酸盐岩台地沉积,可划分为潮坪相和碳酸盐岩台地相及潮上带、潮间带和潮下开阔台地3个沉积亚相;其沉积演化特征显示出7个沉积旋回,每个沉积旋回变化从潮间带(潮上带)沉积开始,海水逐渐加深变为潮下开阔台地沉积,然后海水逐渐变浅,过渡到潮间带沉积,总体上反映了马家沟组沉积期经历了7次较完整的海平面变化过程.研究云台山与青龙峡景区马家沟组沉积环境和沉积演化对于恢复该区早古生代的沉积环境和丰富云台山世界地质公园的地质信息均有重要意义.     

粉体气力输送时弯管的阻力特性及计算方法研究

本文首先综述分析了国内外对不同弯曲曲率半径及角度弯管的阻力特性研究，然后结合作者在多相流动试验台上对４５°、９０°、１１０°、１５０°角度及Ｒ／Ｄ＝２、２．５和３所进行的不同试验结果，采用多变量回归分析法得出适合于计算不同曲率半径和角度的弯管局部阻力系数通用公式，其计算结果与试验值较吻合．     

新疆扇形地及其绿洲的形成演变

扇形地是干旱区绿洲形成与演变的主要地方．扇形地大多沿山问盆地或谷地边缘呈扇状分布，其规模大小与河流水量成正比．据扇形地的规模、组成物质及水源条件等差异，划分为冲积扇、洪积扇、冲-洪积扇、三角洲和泥石流扇等5类，各类特征及绿洲形成发展的条件不同．当地貌过程引起扇形地变形及水土条件发生变化时，绿洲在时空上亦发生变化．引起扇形地演变的地貌过程主要有构造运动、山洪泥石流、滑坡和人为作用等4种．据扇形地水、土条件差异可分为上、中、下及扇缘等地貌部位．绿洲演变可分为早期天然绿洲、人工绿洲发展中期、人工大规模垦荒晚期等三阶段．绿洲演变过程主要有扇形地上部戈壁荒漠→城镇工矿人工绿洲，扇形地中、下部天然绿洲→农田人工绿洲，扇缘沼泽草甸→盐碱地荒漠，农田人工绿洲因盐渍化→盐碱地荒漠演变等4种．     

Relevance between abutment pressure and fractal dimension of crack network induced by mining

Based on the geological conditions of coal mining face No. 15-14120 at No. 8 mine of Pingdingshan coal mining group, the real-time evolution of coal-roof crack network with working face advancing was collected with the help of intrinsically safe borehole video instrument. And according to the geology of this working face, a discrete element model was calculated by UDEC. Combining in situ experimental data with numerical results, the relationship between the fractal dimension of boreholes’ wall and the distribution of advanced abutment pressure was studied under the condition of mining advance. The results show that the variation tendency of fractal dimension and the abutment pressure has the same characteristic value. The distance between working face and the peak value of the abutment pressure has a slight increasing trend with the advancing of mining-face. When the working face is set as the original point, the trend of fractal dimension from the far place to the origin can be divided into three phases: constant, steady increasing and constant. And the turning points of these phases are the max-influencing distance (50 m) and peak value (15 m) of abutment pressure.     

制粉系统水平管道阻力特性及计算方法的分析

本文在分析了大量纯空气和气固两相流在水平管道内流动时摩擦阻力系数人人的计算方法的基础上，结合我们在大型电站锅炉送粉管道中所做的试验，通过分析回归得出了计算送粉管道摩擦阻力系数λμ的经验公式．该公式由于综合大量的试验数据，将为我国《制粉系统空气动力计算》新标准制定，提供更接近工程实际的水平送粉管道阻力计算的方法．     

弯曲型河道水流流速分布及阻力试验

弯曲型河道水流运动规律及阻力特性在水利工程许多领域中占有十分重要的位置.对正弦派生曲线、梯形断面的连续弯曲型河道开展了物理模型试验,采用日本ACM2-RS型X-Y方向2轴电磁流速计对水流流速进行了测量,并对水流阻力进行了分析.结果表明,弯顶水流纵向时均流速分布接近抛物线型,最大流速点位于上部水面以下,整体上大下小,而顺直过渡段水流纵向时均流速分布最大流速点位于底部,整体上小下大;弯道段纵向垂线平均流速横向分布沿程依次为自由涡、均匀流及强迫涡分布;弯顶中垂线水流横向环流随流量、水深的增大而增大,零流速点的相对水深值大致在0.4～0.6范围以内;弯曲型河道水流阻力系数随着过水断面平均水深、水力半径的增大而增大,随着过水断面宽深比的增大而减小.     

Evolution and distribution of macroscopic gas channels in an overburden strata

The evolution of gas bearing channels in the roof, and their spatial distribution, was studied. A complete consideration of gas flow changes through the stress–strain changes in the roof near a working face is made. The theoretical abutment pressure distribution using displacement monitors and borehole visual recording instruments allow a theoretical analysis. Field test research determined the conditions for formation of macroscopic gas channels. These appear along the working face roof, normally distributed to it. These results show that the coal rock stratification becomes a macroscopic gas channel boundary if its deformation is less than the lower layer, or greater than the layer above it. At the same time the stability is greater than the distance from the roof for hanging dew conditions. The working face advances and the roof gas channels experience a cycle of development. Microscopic channels dominate the initial stage then macroscopic gas channels form, develop, and close. The evolution of the macroscopic channels depends on the ratio between the distances from the new compaction area in the goaf to the initial stress area in front of the working face. The amount of daily advance of the face also affects channel development. The experimental observations in one mining area showed that the main gas channels are located about 2 and 6.2 m above the lower surface of the roof and that they have an evolution period 7 to 11 days long.     

明渠中液体流量自动测量的一种新方法

叙述了一种适用于明渠流量测量的新方法．采用特殊结构的电容式传感器及其测量电路并与微型计算机和巴歇尔量水槽结合，可对明渠中清水或浑水的水位、瞬时流量和积累流量进行自动测量．由于采用了多种滤波技术和微机补偿技术，因此测量精度高，性能价格比高，可以替代进口的昂贵仪器．该测量方法适用于城市用水进水渠道的流量测量，也可用于水库的排灌、农田灌溉计量和工厂排污控制．     

寒冷地区东西向住宅演进及户型布局研究

适度发展东西向住宅是推进住宅建设集约化发展的重要途径,本文探讨寒冷地区东西向住宅的实践价值及设计规律,以为贯彻国家节能省地住宅产业策略提供思路.论文探讨了东西向住宅的节地可行性、气候适应性和市场适应性;结合对该类住宅发展演进的研究,指出东西向住宅已成为当今住宅区建设的重要组成部分;进而,通过对住宅户型五种典型布局形式的总结,提出了寒冷地区东西向住宅的适应性设计模式.