Coal and rock fissure evolution and distribution characteristics of multi-seam mining

Henan Pingdingshan No.10 mine is prone to both coal and gas outbursts.The E_(9-10)coal seam is the main coal-producing seam but has poor quality ventilation,thus making it relatively difficult for gas extraction.The F_(15)coal seam,at its lower section,is not prone to coal and gas outbursts.The average seam separation distance of 150 m is greater than the upper limit for underside protective seam mining.Based on borehole imaging technology for field exploration of coal and rock fracture characteristics and discrete element numerical simulation,we have studied the evolution laws and distribution characteristics of the coal and rock fissure field between these two coal seams.By analysis of the influential effect of group F coal mining on the E_(9-10)coal seam,we have shown that a number of small fissures also develop in the area some 150 m above the overlying strata.The width and number of the fissures also increase with the extent of mining activity.Most of the fissures develop at a low angle or even parallel to the strata.The results show that the mining of the F_(15)coal seam has the effect of improving the permeability of the E_(9-10)coal seam.

Coupling control on pillar stress concentration and surface cracks in shallow multi-seam mining

In order to ensure safe mining and reduce surface damage in shallow multi-seam mining,the failure characteristics of interburden strata with different coal pillars offset distances between pillars in the upper and lower seams,the distribution characteristics of stress concentration in coal pillars,and the development characteristics of stratum cracks and subsidence were investigated by physical and UDEC2D simulation.Meanwhile,the effect of different coal pillar offset distances on stress concentration of coal pillar and development of stratum cracks were studied.Based on those results,a formula for safe mining and reducing surface damage was established,which provided a theoretical basis for safe and environmentally friendly mining in shallow multi-seam.According to the results,the optimal coal pillar offset distance(the side to side horizontal distance of the upper and lower coal pillars)between the upper and lower coal seams was developed to reduce the stress concentration of coal pillars and surface damage.The results of this study have been applied in Ningtiaota coal mine and have achieved good results in safe and environmentally friendly mining.

Model test of the overburden deformation and failure law in close distance multi-seam mining

Based on characteristic of the associated mining of multi-coal seam and the engineering geological characteristics of overburden,the mining impact pattern of multi- seam mining and the dynamic fracture mechanism of overburden were characterized by applying the engineering geological mechanical model test.The related strata movement parameters and influence area of multi-seam mining were obtained,the strike boundary angle is 61°,the full extraction coefficient is 0.93,the greatest subsidence angle is 81°,the horizontal movement factor is 0.38,the deviation of inflection point/mining deep is 0.11. The development height of caving zone and water flowing fractured zone of multi-seam mining were calculated,is 32 m and 81.5 m separatly.The assess of influence degree of coal layer safety mining is that,there exists the possibility of water and sand inflow when mining,some messures for mine water prevention and control should be used,and the mining thickness should be local strictly limit.

Geomechanics of subsidence above single and multi-seam coal mining

Accurate prediction of surface subsidence due to the extraction of underground coal seams is a significant challenge in geotechnical engineering. This task is further compounded by the growing trend for coal to be extracted from seams either above or below previously extracted coal seams, a practice known as multiseam mining. In order to accurately predict the subsidence above single and multi-seam longwall panels using numerical methods, constitutive laws need to appropriately represent the mechanical behaviour of coal measure strata. The choice of the most appropriate model is not always straightforward. This paper compares predictions of surface subsidence obtained using the finite element method, considering a range of well-known constitutive models. The results show that more sophisticated and numerically taxing constitutive laws do not necessarily lead to more accurate predictions of subsidence when compared to field measurements. The advantages and limitations of using each particular constitutive law are discussed. A comparison of the numerical predictions and field measurements of surface subsidence is also provided.

De-stressed mining of multi-seams:Surrounding rock control during the mining of a roadway in the overlying protected seam

Surrounding rock control in the overlying protective coal seam is a challenging topic for de-stressed mining of multi-seamed coal.Current research findings on roadway control were used in the design of a physical model of a complex textured roof having a varying thickness.The model was used to study roadway instability and collapse caused by dynamic pressure.The results show that when the thickness of the roof exceeds the bolted depth the roadway security is least and the roof has the greatest possibility for collapse.Numerical simulations were also carried out to study stress redistribution before and after roadway excavation during underlying protective seam mining.The evolution of roadway displacement and fracture,as affected by support methods,has been well studied.A series of support principles and technologies for mining affected roadways has been proposed after demonstration of successful practical application in the Huainan Mines.These principles and technologies are of extended value to deep coal mining support in China.

Interlayer interference mechanism of multi-seam drainage in a CBM well:An example from Zhucang syncline

Based on the characteristics of the strong volatility of physical property in vertical direction, high gas content, high resource abundance and large exploitation potentiality of coal reservoir in Bide-Santang basin of Zhina coal field, we study the generation mechanism of interlayer interference, propagation rules of reservoir pressure drop and influencing factors of gas productivity in CBM multi-seam drainage in the paper. On the basis of the actual production data of X-2 well of Zhucang syncline in Bide-Santang basin,by simulating the gas production process of a CBM well under the condition of multiple seam with COMET3 numerical simulation software, we analyze the influencing factors of gas productivity during the process of multi-seam drainage, and illuminate the interlayer interference mechanism of multiseam drainage. The results show that permeability, reservoir pressure gradient, critical desorption pressure and fluid supply capacity of stratum have great influence on gas productivity of multi-seam drainage while coal thickness has little influence on it. Permeability, reservoir pressure gradient and fluid supply capacity of stratum affect the propagation velocity of reservoir pressure drop and thereby affect the final gas productivity. Moreover, the influence of critical desorption pressure on gas productivity of multiseam drainage is reflected in the gas breakthrough time and effective desorption area.

Lateral Stress Concentration in Localized Interlayer Rock Stratum and the Impact on Deep Multi-Seam Coal Mining

To explore the impact of lateral stress concentration in interlayer rock stratum on the exploitation of protected coal seam, a field experiment was carried out in a multi-seam mining structure. Lateral stress redistribution and interlayer rock failure behavior were surveyed. Then an assistant numerical investigation was implemented to evolve the effect of liberated seam mining and its influence on stress reconstruction in surrounding rock mass. The cause of lateral stress concentration and its impact were discussed finally. Key findings turn out that a certain lateral stress increases in interlayer rock stratum and concentrates on its lower region. Lateral stress concentration and interlayer rock failure are interactional. The former is an inducing factor of the latter;the latter promotes the increase of concentration degree. Extent of lateral stress concentration increases to the maximum as seam distance is about 50 m. But the efficacy of liberated seam mining decreases as the seam spacing gets larger. Protected seam mining is then classified based upon the impact of lateral stress concentration, which helps to prevent the rock burst hazard and then to achieve a reliable mining in deep mines.

Study on the disaster caused by the linkage failure of the residual coal pillar and rock stratum during multiple coal seam mining:mechanism of progressive and dynamic failure

Multi-seam mining often leads to the retention of a significant number of coal pillars for purposes such as protection,safety,or water isolation.However,stress concentration beneath these residual coal pillars can significantly impact their strength and stability when mining below them,potentially leading to hydraulic support failure,surface subsidence,and rock bursting.To address this issue,the linkage between the failure and instability of residual coal pillars and rock strata during multi-seam mining is examined in this study.Key controls include residual pillar spalling,safety factor(f.),local mine stiffness(LMS),and the post-peak stiffness(k)of the residual coal pillar.Limits separating the two forms of failure,progressive versus dynamic,are defined.Progressive failure results at lower stresses when the coal pillar transitions from indefinitely stable(f,>1.5)to failing(f,<1.5)when the coal pillar can no longer remain stable for an extended duration,whereas sud-den(unstable)failure results when the strength of the pillar is further degraded and fails.The transition in mode of failure is defined by the LMS/k ratio.Failure transitions from quiescent to dynamic as LMS/k.<1,which can cause chain pillar instability propagating throughout the mine.This study provides theoretical guidance to define this limit to instability of residual coal pillars for multi-seam mining in similar mines.

多煤层条件下现今地应力特征与煤层气开发

我国煤层气资源较为丰富,滇东地区是我国长江以南著名的煤层气产区,其内雨旺区块二叠系煤层气资源丰富,具有可观的开发前景。现今地应力状态是影响煤层气勘探开发的重要地质因素,对有效开发煤层气资源具有实践指导意义。但目前对雨旺区块现今地应力的研究仅限于利用注入/压降测试数据开展的地应力大小统计学分析,没有揭示出多煤层发育区不同类型岩石内地应力分布的差异性。本次研究中,首先通过对成像测井资料的解译,揭示钻井诱导缝和钻孔崩落的发育特征,并基于其与地应力的关系确定雨旺区块现今地应力方向;然后再利用常规测井资料,在注入/压降实测地应力数据约束下,基于Anderson修正模型预测雨旺区块二叠系煤层现今地应力的大小及其分布规律。结果表明:滇东雨旺区块现今地应力方向整体呈现为近N—S的优势方位;煤层现今地应力大小随着埋藏深度的增加而增大,水平最大主应力(SHmax)、水平最小主应力(Shmin)和垂向主应力(Sv)大小总体上遵循SHmax≥Sv>Shmin的关系,水平应力起主导作用,表现为走滑型应力机制。在现今地应力场的控制下,雨旺区块内煤储层渗透性随有效地应力的增大而变差,煤层内走向为330°~150°的割理对煤层气开发贡献更大。走滑型应力机制会造成煤层压裂改造后形成的压裂缝沿垂向扩展。另外,雨旺区块煤层内水平应力差相对较小,一般在6 MPa左右,据此推测可在煤层内形成复杂压裂缝系统。本次研究量化分析了雨旺区块现今地应力状态,其结果可以为滇东雨旺区块煤层气勘探开发提供有益的现今地应力成果参考。

不同地质条件下土壤重金属质量评价比较

对黎塘研究区不同地质条件下土壤重金属含量进行了分析和评价。结果表明,不同地层土壤以Mn含量最高,其次为Cr,石炭系下统岩关阶和泥盆系中统东岗岭阶土壤重金属含量较高,而白垩系下统小店组和第四系全新统土壤重金属含量较低。泥盆系中统东岗岭阶土壤重金属污染因子为Ni、As、Cr,综合质量级别为中等;石炭系下统岩关阶土壤重金属污染因子为Ni、As、Cr、Cu,综合质量级别为很坏;白垩系下统土壤污染因子为Cr,综合质量级别为警戒级;第四系全新统土壤重金属质量级别均为好,综合质量级别为好。

地生枝顶孢RCEF0260多糖提取工艺的研究

本文对地生枝顶孢RCEF0260菌株液体深层发酵液中胞内、胞外多糖的提取工艺进行了研究。结果发现采用机械法处理RCEF0260菌丝体,多糖得率从21.5g/kg干菌体提高到27.0g/kg干菌体,利用正交试验结果得到胞内多糖的提取工艺参数温度60℃,加水量2.5mL.g-1,浸提时间为1.5h,次数2次;RCEF0260胞外多糖的提取工艺参数乙醇终浓度为65%,发酵液浓缩到1/2,浓缩的温度为40℃。

聚醚改性有机硅季铵盐在香波中的应用研究

研究了阳离子型聚硅氧烷季铵盐的乳化性能及在香波中作为头发调理剂 ,对头发干、湿梳理效果的影响。实验表明 :乳液粒径主要分布在 10 μm附近 ;香波中加入 2 %的阳离子型聚硅氧烷季铵盐对湿梳理效果提高了 2 8.0 % ,干梳理效果提高了 2 1.2 % ,比普通乳化硅油具有更好的调理性能。

红豆杉胚源细胞株的培养和紫杉醇的生产

研究了建立适用于紫杉醇生物合成的红豆杉 ( Taxus chinensis)胚源细胞株的方法 .红豆杉成熟种子 ,用自来水冲洗 9d,培养 1 0 d,萌发率可达 1 0 0 %.已萌发的种胚在诱导培养基中培养 6d,愈伤组织的诱导率达 1 0 0 %,使用红豆杉茎源细胞株看护培养诱导出的愈伤组织使愈伤组织的继代成活率提高一倍 .红豆杉茎源细胞株生长 1 5d的条件培养液也能使愈伤组织继代成活率提高 60 %.对建立的胚源细胞株进行了筛选和培养 ,其中细胞株 E2和 E3生长快 。

环境因子对鸟巢蕨生长的影响

[目的]探讨环境因子对鸟巢蕨生长的影响。[方法]对适宜于鸟巢蕨作为切叶生长的湿度和光照强度进行了研究。[结果]初步探明,湿度80%、遮阳率80%是鸟巢蕨作为切叶栽培的较为适宜的生长条件(在海口市,夏季),该条件下其叶片又长又宽、颜色鲜绿、张开角度较大,长出新叶最多。[结论]为鸟巢蕨栽培提供了理论依据。

重庆市高校素质教育现状及其对策

重庆市高校素质教育经历了三个发展阶段,形成了以基地建设为契机,思想素质教育为基础,文化素质教育为切入点,巴渝文化为特色,红岩精神为主线的新格局。为进一步深化素质教育,有必要实施素质教育的全面推进战略,突出素质教育的个性化,树立文化素质教育课程精品化意识,注重素质教育的"内化"功能。

非对称球面五杆机构的奇异轨迹与灵巧度分析

针时非对称球面五杆机构,研究了机构的奇异轨迹曲线和灵巧度。首先建立了球面五杆机构的运动学正、反解模型,并导出了机构的速度方程和雅可比矩阵。基于机构的雅可比矩阵,对机构的奇异位形和灵活度进行了计算分析,绘制了机构的奇异轨迹和灵巧度分布曲线,并讨论了球面五杆机构的结构参数对机构全条件指标的影响。

缺血后处理对脑缺血再灌注损伤后ERK1/2和Akt磷酸化及神经细胞凋亡的影响

目的:观察缺血后处理对大鼠局灶性脑缺血再灌注损伤后ERK1/2和Akt及神经细胞凋亡的影响。方法:成年健康SD大鼠72只,随机分为假手术(sham)组、缺血再灌注(I/R)组、缺血后处理(Postcond)组各24只,应用线栓法建立大脑中动脉闭塞(MCAO)再灌注模型。分别于再灌注10min、30min、6h、24h后留取大脑皮质。Western blot检测再灌注10min、30min、6h后ERK1/2和Akt活性变化;原位末端标记(TUNEL)检测再灌注后24h神经细胞凋亡。结果:Postcond组再灌注10min、30min、6h后ERK1/2和Akt活性高于I/R组(P<0.05);脑缺血再灌注24h后,Postcond组与I/R组比较,TUNEL阳性细胞减少(P<0.05)。结论:缺血后处理可提高大鼠脑缺血再灌注后皮质内ERK1/2和Akt活性,减少神经细胞凋亡。

阳离子有机硅香波调理剂的制备及性能研究

以低含氢硅油、不饱和聚醚、一氯乙酸和二甲胺为原料 ,制备得阳离子有机硅油。通过红外光谱对产物组成进行了表征 ,并研究了其在香波中的调理性能。研究表明 :加入质量分数为 2 %的产物湿梳理效果提高了 19.3% ,干梳理效果提高了 10 .0 % ,比普通乳化硅油具有更好的干湿梳理性能。

发酵白酒糟生产饲料蛋白工艺研究(Ⅰ)——发酵条件单因子分析

目的 :研究发酵白酒糟生产饲料蛋白的发酵条件 ,为工业化生产工艺提供技术支持 .主要研究原料处理、培养基制备、以及混菌比例和发酵的时间、温度、湿度、空间湿度、通气性等因素对发酵产物粗蛋白含量的影响 ,从而获得最佳发酵条件 .方法 :采用单因子分析法 ,分别获得各因子的最佳发酵条件 .结果 :原料经适当粉碎后 ,加入辅料 ,调 pH值为 6 5经常压或高压灭菌 .晾至 30～ 40℃时 ,以 1∶1∶1混菌比例 ,5 %～ 7%的接种量接入培养基 ,用竹筛曲盘 ,料层厚度为 3～ 5cm ,90 %～ 95 %空间湿度 ,2 8～ 32℃保持 40～ 5

马厂地区深层气滚动勘探开发的几点做法

中原油田 2 0 0 1年在马厂地区沙四下段首次获得高产工业气流 ,首次上报了天然气探明储量 ,展示了马厂地区深层气的良好勘探前景。在分析滚动勘探开发效果的基础上 ,总结了马厂地区在老井复查、资源潜力分析、油气控制因素、油气富集规律、有利目标选择、构造精细研究、滚动井位部署等工作的主要做法 ,为以后深层气的滚动勘探开发起参考。