Numerical simulation of seepage field of gas extraction drilling of single bedding of mining-coal bed

Aiming at the problem of reasonable decorate of coal gas extraction drilling, combining with the initial and boundary condition of borehole extraction, the solid and gas coupling mathematical model of gas seepage of borehole extraction is deduced based on established control equations of seepage field and deformation field. Taking gas extraction of stone coal slit as an example, according to the characteristics of coal seam in the research, the numerical simulation method is used to obtain the distribution rule of gas pressure, coalbed gas permeability, and coalbed gas seepage velocity as well as seam deformation. The effective radius of gas extraction drilling of single bedding about mining-coal bed is determined, which provides the basis for optimum arrangement of gas extraction drilling of single bedding. The results show that the effective radius of stone coal is about 4 m. If the prolonging drilling drainage time is less than 20%, the drilling quantities would reduce by about 50%.     

The influence of stress sensitivity on productionof hydraulically-fractured tight gas wells

This paper takes Sulige Gas Field as a case study and used three methods including laboratory experiments,production performance analysis and reservoir simulation to study the influence of stress sensitivity on production of fractured tight gas wells.The results show that the fracture length and conductivity of hydraulically created fracture are reduced more than 50%,and the stress sensitivity of hydraulically created fracture is stronger than that of matrix.With the increase of gas production,the influence of stress sensitivity becomes stronger,and finally results in 18% reduction of gas production,and hydraulically created fractures play an important role in the influence of stress sensitivity.     

对称式基坑渗流涌水量的计算方法

随着地铁、越江隧道等地下工程的日益增多,涌现出了大量的对称式基坑。基于共形映射理论,推导了对称式基坑涌水量计算表达式,并对其计算参数进行分析。研究表明,对称式基坑的单宽涌水量与渗透系数、基坑内外水头差成正比,与（相对）隔水层层顶到坑底的距离和基坑两侧止水帷幕间距的比值、止水帷幕嵌固深度和（相对）隔水层层顶到坑底距离的比值、基坑内外水头差和（相对）隔水层层顶到坑底距离的比值成反相关。     

Study on Adsorption Characteristics of Coal to Gas in Geophysical Field

It is very important to mine safe exploitation, gas drawing and predict of coal and gas outburst that adsorption characteristics of coal to gas in geophysical field are studied. Adsorption and desorption characteristics of coal to gas in geophysical field have been reviewed in detail, then it is obtained that adsorption characteristics of coal to gas in electromagnetic field should be further studied . Adsorption and desorption characteristics of coal to methane in alternating electric field (AEF) have been studied mainly. Adsorption characteristics of three coal samples in AEF have been studied by means of Volume Method. The result shows that chemical properties and matter constituent of coal surface are no changed , adsorption and desorption of the coal samples in AEF well accord with Langmuir equation and two constants empirical formula, and because coal potential energy is increased and coal temperature is raised caused by Joule heat effect , adsorption ability of coal is decreased, and the desorption process is slowed down in AEF.     

Key Layer and Stress Dike Mechanism of Coal and Gas Outbursts

The outburst coal mass is a geologic body which had objectively existed before outbursts occurred.The authors think the occurrence and development of coal and gas outbursts are controlled by comprehensive factors according to a host of facts of outbursts in their researches,and all the factors belong to the system of "rock coal gas rock".Therefore the authors put forward a completely hypothesis,i.e.key layer and stress dike mechanism of coal and gas outbursts.This hypothesis emphasizes that the outbursts are the result of comprehensive action by coalbed gas,abutment stress and physical and mechanical properties of coal.Of special interest is emphasizing the geologic backgroud and conditions of outbursts to a great extent.Any phenomenon of outbursts which a person could observe could be qualitatively explained with the hypothesis so that the hypothesis can serve the study of geophysical field of outbursts perfectly.     

热流固耦合作用下页岩渗透特性实验

为探讨地温对页岩渗流特性的影响规律,按照温度对页岩作用部位的不同,从流体动能、骨架应变、吸附解吸三个方面,分析甲烷内摩擦力对动能的影响、页岩热应力及热膨胀导致应变、甲烷解吸引起基质收缩随温度变化的规律,得出热流固耦合作用下页岩渗流特性。以渝东南酉阳龙马溪组页岩样品为分析对象,进行页岩型岩的温度渗流实验,提出三方面五因素的分析方法：温度增加,流体内摩擦力增大减小了流动速度;粘土矿物与有机质的差异性膨胀产生热应力,压缩了页岩骨架,加之基质热膨胀减小了基质间隙,双重作用使渗流通道减小;基质收缩效应对孔隙裂隙双重结构介质渗透量影响很小。温度升高对页岩渗流特性的主要影响体现为,内摩擦力的减速作用及热应力和热膨胀对渗流通道的压缩作用。     

施肥对油菜田土壤CO2排放的影响

为了评价不同施肥方式对油菜田温室气体CO2排放影响,从而更好地引导农民改善施肥方式,减少温室气体排放。本研究以巢湖油菜田优化施肥（YH）、秸秆施肥（JG）、习惯性施肥（CG）和不施肥（CK）4种施肥类型为研究对象,利用静态箱-气相色谱法测定油菜生长期间的CO2的排放通量,同时对土温、土壤含水量和空气湿度进行测定。通过对数据进行相关性分析,结果表明：不同的施肥处理对CO2的排放有较大影响,其中CK处理的CO2排放通量最小;不同施肥方式对CO2的排放有影响,但差异不显著。10 cm以下深度的土壤温度对进行JG的油菜的CO2排放有极显著正相关关系。土壤含水量对温室气体CO2的影响只有与秸秆施肥（JG）的处理呈显著负相关性。并认为在这4种处理中YH施肥是最值得推广的施肥方式。     

考虑渗流和地震时的砂土边坡稳定性计算

基于极限平衡理论,以砂土边坡为研究对象,推导了渗流和地震存在时拟静力法和拟动力法边坡安全系数的计算表达式。通过程序求解,与已有算例对比表明,计算结果基本一致,验证了2种方法解析式的合理性。参数分析表明,水位越高,边坡失稳越严重,水力梯度与安全系数基本为线性关系。渗流方向向下时,稳定性随水力梯度的增加而增大;渗流方向向上时,变化规律相反。水平地震加速度系数对稳定性的影响剧烈,竖向地震加速度系数对稳定性影响较小,简化计算可以忽略不计。最终得出拟静力法的解析式,简单、实用,而拟动力法则可以更为全面地考察砂土边坡稳定性随时间变化的特点。     

Numerical simulation on the seepage of tailings dam by centerline method construction

Yangla copper mine is going to build a new tailings pond for its tailings disposal. The tailings dam is 185.0 m high and centerline method is used to construct the tailings pond. For the stability of the tailings dam, 2D FLOW program is used for the numerical simulation study about the dam seepage. During simulation calculation, different conditions which include a drainage system installed into the dam or not and different beach widths, i.e. 70 (the flood condition), 100, 300 m (the normal condition), are considered. Through calculation, the change of the seepage under different conditions is obtained, which shows if the drainage system is installed into the tailings dam, the underground water can be successfully drained out. This can keep the phreatic surface level relatively low, so as to improve the stability of the dam.     

Finite element analysis of high contact-ratio gear stress field

Based on the elastic contact finite element method(FEM),three-dimensional static contact model of high-contact-ratio gears is established. The Newton-Raphson(NR) method is used to get the contact stress. Load distribution factor of gear teeth and the influence of different friction coefficients were achieved by the FEA. Comparison with Hertz contact stress, the maximum contact stress is less than Hertz stress. Natural frequencies and major modes of the gear are calculated by the Lanc20s method, and the results provided theoretical basis for the design and application of helical involute gear.     

直墙拱形巷道围岩应力场分析

为得出直墙拱形巷道围岩应力分布规律,应用复变函数弹性理论推导了直墙拱形巷道围岩应力分布的解析表达式。对直墙拱形巷道边界的围岩应力和巷道水平线方向的围岩应力分布规律进行分析,并考虑直墙拱形巷道断面高宽比和侧压系数对其影响规律。研究表明：在不同巷道断面高宽比、侧压系数下,直墙拱形巷道围岩应力集中区域主要集中在直墙底部底角处、拱形顶板中点附近和底板中部3个位置。不同巷道断面高宽比下,直墙拱形巷道沿水平线的应力分布规律基本相同。侧压系数大于1时,采用巷道断面高宽比小于1较有利于巷道稳定;侧压系数小于等于1时,采用巷道断面高宽比大于1较有利于巷道稳定。     

The Influence of In-situ Stress Gradient and Geothermal Temperature on The Calculation of Coalbed Gas Pressure

On the basis of coal seam having outcrop of coal seam and outlet on ground,the method for calculating coalbed gas pressure from the one-dimensional stable gas flow equation by considering deeply the influence of in-situ stress gradient and geothermal temperature is presented. In some mine, the theoretically computing and measuring results of coalbed gas pressure show that the in-situ stress gradient and the geothermal temperature have important influence on the calculation of coalbed gas pressure, and if the factors are drew into the calculation of coaled gas pressure,it will make the results much more accurate.     

Experimental analysis of coal bed methane desorption and seepage under sonic vibrating of cavitation water jets

A way to enhance coal bed methane desorption and seepage by sonic vibrating of cavitataion water jets is proposed because the gas coal seams have the intrinsic properties of micro-porosity, low permeability and high adsorption. The mechanisms of how the sonic vibrating effects promote methane desorption and seepage are analyzed, and the contrast experiments of methane desorption and seepage under sonic vibrating effects are also provided. The results show: when the cavitation number is 0.020 0, under sonic vibrating effects, the volume of coal bed methane desorption increases by 36.9%, and the time for coal bed methane desorption reduces by 19.6%. The speed of coal seams methane seepage is significantly increased by 35.3% and arrives at 0.383 3 ml/s.     

NaCl胁迫对不同染色体倍性西瓜种子发芽特性的影响

用盐水浸种催芽方法,通过对蜜枚西瓜的二倍体、三倍体、四倍体在不同浓度NaCl胁迫下种子的发芽率、胚轴长度以及鲜重、发芽指数、活力指数等指标的测定,在30~90mmol/L低浓度下,倍性之间相对发芽率没有明显差异;在120 mmol/L以上浓度时,不同倍性之间差异明显,在150mmol/L NaCl胁迫下,其M4x、M3x、M2x相对发芽率分别为77.8%、63.4%、30.6%,180mmol/L时分别为37.8%、31.7%、0,在210mmol/L时,M4x和M3x仍然有种子萌发,耐盐性为M4x＞M3x＞M2x。     

An ultrasonic vibration based test system for the study of coalbed gas

Based on the influence of ultrasonic vibration on the adsorption/desorption and seepage characteristics of coalbed gas, a test system for the measurement of adsorption and seepage characteristics of coalbed gas was designed. The main component of the system is a pressure testing device. The test system consists of six parts, including an intelligentized acoustic generator, adsorption and seepage devices, a pressure supply, a deformation measurement component, a gas supply and a deformation tester. The function and operating method of the test system were introduced in detail. Experimental results show that the test system can meet completely the requirements for the characterization of adsorption/desorption and seepage of coalbed gas in either the presence or absence of an ultrasonic field.     

Elasto-plastic analysis on surrounding rock of roadways based on seepage, strain softening and dilatancy

According to seepage body force, strain softening and rupture expansion of rock mass, elastic-plastic mechanics theory, distribution laws of stress and displacement of surrounding rock in seepage field are derived, and relationships between different zonation range of the surrounding rocks, pore water pressure, strain softening and rupture expansion are established. The results show that the pore water pressure and rupture expansion rock mass have a more obvious impact on the surrounding rock rupture area than the plastic zone. Both the plastic zone and the rupture area are larger when the seepage field is considered. The impact of strain softening on both the plastic zone and the rupture zone of surrounding rock is very significant, and both seepage and strain softening rupture expansion affect deformation of surrounding rock of roadways obviously. It provides certain reference values for the roadway support engineering in seepage field.     

Impact of heat stress on pod-based yield components in field pea (Pisum sativum L.)

Elevated temperatures associated with climate change result in crops being exposed to frequent spells of heat stress. Heat stress results in reduced yield in field pea (Pisum sativum L.); it is therefore important to identify cultivars with improved pod and seed retention under heat to mitigate this loss. Objectives were to investigate the effect of heat stress on phenology, yield and pod-based yield components. Sixteen pea cultivars were evaluated at normal and late (hot) seeding dates in the field in Arizona 2012 and in growth chambers with two temperature regimes (24/18°C and 35/18°C day/night temperature for 7 days) during reproductive development. We measured variation in the pattern of pod retention at four-node positions on plants, seed retention by ovule position (stylar, medial and basal) within pods and screened cultivars for pod retention, seed retention and yield. Heat stress reduced seed yield by accelerating the crop lifecycle and reducing pod number and seed size. Heat stress had the most damaging effect on younger reproductive growth (flowers and pods developed later), resulting in ovary abortion from developing flowers. Heat also accelerated seed abortion in all ovule positions within pods. Two high-yielding cultivars under control temperature, “Naparnyk” and “CDC Meadow”, maintained high yield in heat, and “MFR043” had the lowest yield. Cultivars “40-10” and “Naparnyk” retained the most ovules and seeds per pod, and “MFR043” aborted seeds when exposed to heat. In half of the cultivars, ovules at the basal peduncle end of pods were likely to abort while ovules at the medial and stylar end positions developed into seeds. For seven of the field cultivars, ovules at the medial pod position also produced mature seeds. Cultivars “40-10”, “Naparnyk” and “CDC Meadow” had greater pod and ovule retention or maintained high yield under heat stress, and were identified as heat-tolerant cultivars. Our results allow for a better understanding of pod-based yield components in field pea under heat stress and developing heat-tolerant cultivars.     

Hybrid field network simulation of temperature in a building fire

A connecting platform between the field model and network model has been constructed, based on a multi functional building model. The field model is used to simulate the fire smoke in certain special compartments (the fire room and specific large space rooms), while the network model is used to simulate the uniform compartments. When combining the simulation results of the field model and network model as the interface boundary conditions for the each other, a hybrid field and network model is presented. The hybrid field network model can provide more detailed physical information of the fire smoke properties under a specific fire scenario for the specially confined compartments. In addition, the hybrid model can predict the fire smoke flow properties in the building accurately.     

水淹胁迫对华南地区3种园林树种生理特征的影响

为了了解红荷、红苞木、樟树幼苗的抗涝能力,为筛选优良的抗涝树种提供依据,通过人工模拟水淹胁迫环境,测定这3种幼苗叶片的叶绿素等生理指标,用主成分分析法研究了这3种幼苗的抗涝性。研究结果表明：随着水淹胁迫时间的延长,红荷幼苗叶片叶绿素含量波动,红苞木和樟树小幅上升后下降;3种幼苗叶片的可溶性糖含量呈波动性上升的趋势;红苞木和樟树的蛋白质含量呈现波动性变化,红荷的蛋白质含量为降-升-降;红荷的叶片的超氧化物歧化酶(SOD)活性呈逐渐下降趋势,红苞木和樟树的SOD活性显著上升后下降;红荷、红苞木和樟树幼苗叶片的丙二醛(MDA)含量大幅增加后缓缓下降。3种幼苗在水淹28天期间内均有一定的抗涝性,采用主成分分析法得出幼苗的抗涝性大小为樟树>红荷>红苞木。