采高对下层煤回采巷道稳定性影响分析

针对近距离煤层下层煤回采巷道布置在应力降低区时,掘进过程中仍出现围岩破碎、局部地段有底鼓的现象,采用理论分析的方法,对不同采高情况下上层煤遗留煤柱上支承压力分布规律进行分析,结合煤矿实际利用计算机对不同采高时下部煤层巷道围岩力学特征进行数值模拟,得出随着采高增大下层煤回采巷道受上层煤采动影响越大,下层煤巷道靠近煤柱一帮破坏越严重,巷道底鼓量越大的规律.为采高变化时下层煤回采巷道支护参数设计提供了依据.     

低频机械振动影响煤样吸附特性研究

利用自制的瓦斯吸附/解吸激振及测试系统,研究了不同振频对煤样吸附性能的影响.试验结果表明：不同振频对未吸附饱和煤样影响不同,10Hz促使瓦斯吸附,20,30Hz抑制吸附;趋于吸附饱和煤样受振动影响很小.进一步分析振频与扩散的关系,发现充入相同气压,振动对瓦斯孔隙吸附量影响不明显,参数B和瓦斯扩散系数均按30,20,0,10Hz逐步变大;并依据扩散特性定义了扩散度.趋于吸附饱和时,煤与瓦斯系统处于振动状态下的动态吸附平衡.采掘过程中,振频越大,受振动影响而内压改变的那部分煤体越可能瞬时突出;振频越小,突出延迟越可能出现.     

综采面邻空煤柱漏风微循环现象研究

针对综采面"采场-邻空煤柱-采空区"间的漏风微循环现象,利用MATLAB中的PDE工具进行二维非线性渗流的数值模拟,同时分析研究漏风微循环现象形成的原因,以及漏风微循环对煤炭自燃的影响。研究表明,"采场-邻空煤柱-采空区"间的漏风微循环可以导致采空区内相对压力和气体成分的周期性变化,即"采空区喘息"现象。     

聚丙烯纤维与聚酯纤维对混凝土力学性能影响的研究

为了研究水胶比、粉煤灰、聚丙烯纤维与聚酯纤维对混凝土力学性能的影响,通过正交试验,以混凝土抗压强度与劈裂抗拉强度为考核指标,确定出最优组合.根据最优组合制备的聚丙烯纤维和聚酯纤维混凝土与未掺纤维的混凝土相比较得出,聚丙烯纤维和聚酯纤维均使混凝土抗压强度略有提高,劈裂抗拉强度和抗折强度提高程度较大;聚丙烯纤维混凝土与聚酯纤维混凝土相比,前者抗压强度略高于后者,但后者劈裂抗拉强度和抗折强度高于前者.     

应变速率对注浆体力学特性影响规律

为研究微震荷载作用下注浆加固体力学特性,以裂隙倾角30°、宽度4 mm的红砂岩裂隙注浆体为研究对象,借助岩石三轴伺服压力机进行变应变速率(10^-5 ~5×10^-3 s^-1)单轴压缩试验;然后从能量耗散、裂纹扩展及破坏形态等3个方面,分析变应变速率对注浆体力学特性的影响规律及机理. 研究表明:随着应变速率的增加,注浆体的峰值强度、弹性模量均随之而增大;且峰值强度与应变速率呈指数函数关系变化;注浆体受应变速率影响的响应分为敏感应变速率阶段和滞缓应变速率阶段,主要差异在于峰值强度变化率和弹性模量变化率;随着应变速率的增大,注浆体的总能量在增大;压密阶段是影响不同应变速率下注浆体力学特性的主要阶段;敏感应变速率阶段和滞缓应变率阶段中的压密阶段主要区别在于积散比大小,积散比进一步决定产生裂纹的多少和分布区域与规律;耗散能密度对注浆体破坏脱落面积以及粒径分布影响较大,耗散能密度越大,碎块越以大块为主(粒径大的比率逐渐增加),滞缓应变率阶段耗散能密度较敏感应变率阶段大,其破碎块体较敏感应变率阶段大. 研究在裂隙注浆加固体的变应变速率影响下力学特性,从能理原理、分形理论角度得到了其影响机理.     

Influence of the morphology on mechanical properties of toughened epoxies with CTBN

0　ＩＮＴＲＯＤＵＣＴＩＯＮＵｎｍｏｄｉｆｉｅｄｅｐｏｘｉｅｓａｒｅｂｒｉｔｔｌｅｐｏｌｙｍｅｒｓｗｉｔｈｐｏｏｒｒｅ ｓｉｓｔａｎｃｅｔｏｃｒａｃｋｐｒｏｐａｇａｔｉｏｎ .Ａｃｏｎｓｉｄｅｒａｂｌｅｉｎｃｒｅａｓｅｉｎｔｈｅｃｒａｃｋｒｅｓｉｓｔａｎｃｅｉｓｏｂｔａｉｎｅｄｂｙｇｅｎｅｒａｔｉｎｇａｐａｒｔｉｃｕ ｌａｔｅ ｄｉｓｐｅｒｓｅｄｓｅｃｏｎｄｐｈａｓｅ .Ｔｈｅｐｒｅｓｅｎｃｅｏｆａｄｉｓｐｅｒｓｉｏｎｏｆｒｕｂｂｅｒｙｐａｒｔｉｃｌｅｓｗｉｔｈｓｉｚｅｓｉｎｔｈｅｒａｎｇｅ 0 .1～ 5μ…     

侵蚀性离子对水泥土力学特性的影响

水泥土搅拌法的施工工艺及水泥土的应用特点使其经常处于具有侵蚀性离子的环境中.为此，利用试验模拟了侵蚀性离子的存在，对不同离子浓度、不同水泥掺量的水泥土试件在各龄期进行了试验研究，并对侵蚀机理进行了分析.结果表明，SO₄^2-和Cl^-对水泥土的侵蚀性均比较明显，其中Cl^-的侵蚀性与水泥的掺量有关；而SO₄^2-的浓度在一定范围内对水泥土的强度具有一定的增强作用.对水泥土在复杂工程环境中的应用具有参考价值.     

不同Mg/Si比对含Zn的Al-Mg-Si合金再结晶组织及性能的影响

为改善Al-Mg-Si系合金汽车板综合性能,通过浇铸法制备出3组合金成分铸锭,并经过均匀化、热轧、中间退火、冷轧,获得1 mm厚的合金板材.合金板材经560℃固溶30 min后,立即在100℃条件下预时效8 h,室温停放14天,模拟铝板转运存储过程,并拉伸变形2%,再在185℃下进行20 min烘烤处理,实现烘烤硬化.采用金相显微镜、装备电子背散射衍射的扫描电镜对合金进行显微组织观察及织构分析,通过万能电子试验机进行力学性能测定,研究不同Mg/Si比和高Zn元素对合金再结晶组织及织构、烘烤硬化性以及腐蚀敏感性的影响.结果表明,Mg/Si比相等合金再结晶组织更加均匀细小,平均晶粒尺寸190μm,存在相对较少的Cube织构{001}100和较多的P型织构{011}122;高Mg合金、高Si合金局部晶粒粗大,Cube织构{001}100较多,P型织构{011}122较少;预时效后,Mg/Si比相等合金强度较高,且烘烤硬化性优异,烤漆硬化增量达到107 MPa;烤漆后,更多的Zn原子扩散到晶界上,强化晶界微电流反应,欠时效态Mg/Si比相等合金较高Mg合金、高Si合金抗腐蚀敏感性降低,被腐蚀深度为121μm.     

不同偶联剂对秸秆／PP复合材料力学性能的影响研究

通过对秸秆粉的质量分数、偶联剂的种类及其含量等因素的控制,研究上述因素变化对PP／秸秆粉基木塑复合材料的各项力学性能的影响．研究结果表明：四种不同偶联剂中马来酸酐接枝聚丙烯（MAPP）的效果最好;当秸秆粉质量分数达到30％时,木塑复合材料的抗弯强度、抗拉强度、抗冲击强度均为最佳;采用MAPP作为偶联剂且含量为秸秆粉的4％时,材料的抗弯、抗拉强度、抗冲击强度均为最佳,当MAPP含量超过4％时,材料的力学性能会有所下降．     

不同含水率下滑带土的力学特性研究

通过中剪试验和侧限压缩试验,研究同一干密度、不同含水率条件下滑带土的抗剪强度、内聚力、摩擦系数和侧限压缩试验中孔隙比、压缩系数、压缩模量的变化规律等。结果表明:随着含水率的增加,抗剪强度呈线性减小,内聚力和摩擦系数减小,可用对数方程表示。孔隙比、压缩系数和压缩模量变化显著,但敏感性有所不同。     

Influence of cerium on microstructures and mechanical properties of Al-Zn-Mg-Cu alloys

Effect of element cerium (Ce) on microstructure and mechanical properties of Al-Zn-Mg-Cu alloys has been investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and hardness test. The results show that addition of Ce can remarkably refine the as-cast grains and eutectic microstructure. A transformation from Mg(Zn,Cu,Al)₂ phase to Al₂CuMg phase is observed during homogenization. Furthermore, the Ce addition introduces changes in the precipitation process and consequently in the age-hardening behavior of the alloy. Microstructural measurements reveal that the addition of Ce promotes the precipitation of η′ phase, but it also partly retards the precipitation of GP zones. The density of precipitates decreases in a certain degree and rod-like η′ precipitates increase when Ce content is from 0.2% to 0.4% (mass fraction).     

煤矿开采对高速公路影响的评价

从煤矿井田中部穿过的高速公路在建设和运营过程中,必须及时掌握煤矿地下开采对其采动影响情况.根据煤矿地质采矿条件,对煤矿地下开采在高速公路沿线所引起的地表移动和变形进行预计,给出高速公路沿线地表移动变形值.由预计结果评价了煤矿开采对高速公路的损害程度.结果表明,煤矿开采后引起的地表变形值超过了高速公路的允许变形值,它对高速公路的采动损害程度明显.     

巨厚煤层冲击地压的防治研究

通过对义煤集团千秋煤矿有冲击倾向巨厚煤层冲击现象现状、特点及影响因素分析,结合该矿的生产实践,提出了适合该条件的冲击危险预测方法及相应解危措施,并进一步提出解危措施效果检验方法以及以上工作失败、冲击地压突发情况下的应急措施;在此基础上建立了适合义煤千秋矿巨厚煤层冲击地压防治的安全开采体系,成功地进行了巨厚煤层的综放开采,从而为有冲击倾向巨厚煤层的安全开采提供了成功范例.     

Deformation response of roof in solid backfilling coal mining based on viscoelastic properties of waste gangue

Solid backfill mining(SBM) is a form of green mining, the core of which is to control and minimize the deformation and movement of strata above longwall coal mines. Establishing a mechanical model that can reliably describe roof deformation by considering the viscoelastic properties of waste gangue is important as it assists in improving mine designs and reducing the environmental impact on the surface.In this paper, the time-dependent deformation characteristics of gangue under different stress levels were obtained by using lateral confinement compression, that reliably represents the compaction of goaf.The viscoelastic foundation model for gangue mechanical response is different from the traditionally used elastic foundation model, as it considers the time factor and viscoelasticity. A mechanical model using a thin plate on a fractional viscoelastic foundation was established, and the roof deflection, bending moment, time-dependent, viscous and other characteristics of SBM were included and analyzed.Compared with the existing elastic foundation model, the proposed fractional order viscoelastic foundation model has higher accuracy with laboratory data. The plate deflection increases by 50.9% and the bending moment increases by 37.9% after 100 days, which the elastic model would not have been able to predict.     

正火工艺对球铁组织及力学性能的影响

从标准梅花试块制取标准试样并进行系列正火处理 ,观察金相组织 ,测定力学性能 ,初步确定了可行的球铁正火工艺及参数     

Influence of hot rolling conditions on the mechanical properties of hot rolled TRIP steel

Influence of hot rolling conditions on the mechanical properties of hot rolled TRIP steel was investigated. Thermomechanical control processing （TMCP） was conducted by using a laboratory hot rolling mill, in which three different kinds of finish rolling temperatures were applied. The results show that polygonal ferrite, granular bainite and larger amount of stabilized retained austenite can be obtained by controlled rolling processes. The finer ferrite grain size is produced through the deformation induced transformation during deformation rather than after deformation, which affects the mechanical properties of hot rolled TRIP steel. Mechanical properties increase with decreasing finish rolling temperature due to the stabilization of retained austenite. Ultimate tensile strength （UTS）, total elongation （TEL） and the product of ultimate tensile strength and total elongation （UTS×TEL） reaches optimal values （791 MPa, 36% and 28 476 MPa%, respectively） when the specimen was hot rolled for 50% reduction at finish rolling temperature of 700 ℃.     

激光熔凝处理对轧辊钢组织及性能的影响

应用3KW连续CO2激光器对轧辊钢进行激光熔凝处理,用金相用显微镜、、SEM及71型显微硬度计,进行湿微组织分析和显微微硬度测试。结果发现,其剖面组织区域分为熔化区（粗大的马氏体＋残余奥氏体→奥氏体)、相变区（马氏体＋残余奥氏体＋碳化物）、热影响区和基体4个部分,各区域的尺寸及显微硬度与功率、扫描速度等工艺参数有关,且激光处理后硬化效果明显。     

Classification of conditions for short-wall continuous mechanical mining in shallowly buried coal seam with thin bedrock

The room and pillar method is usually used to extract coal from shallowly buried seams with thin bedrock. This results in a very low production efficiency and in a low degree of extraction. In recent years short-wall continuous mechanical mining has been extensively used in many situations except shallowly buried coal seams with thin bedrock. The principles governing movement of the overlying strata above the 2.<,2. coal seam were deduced from in-situ experience, laboratory data, calculations and computer simulations. The thicknesses of the bedrock in the Shendong Coal Field where the coal is shallowly buried are classified into 5 types: <10 m, 10-15 m, 15-25 m, 25-35 m and >35 m, which was done using fuzzy clustering results. A series of reasonable,relative parameters in each category have been calculated and analyzed. One proposed way to perform short-wall continuous mechanical mining in shallowly buried coal seams is given. This is significant for coal mines with similar geological conditions.     

控制冷却参数对普碳钢组织性能的影响

以普碳钢为研究对象,对轧制后的板材进行控制冷却实验.结果表明,采用轧后自动控制冷却系统进行控制冷却,可以保证终冷温度与目标值误差在10℃以内,达到了较高的控制精度.经拉伸和冲击实验及带状组织分析发现,提高控制冷却工艺的开冷温度,对控冷参数进行优化可显著细化晶粒、改善性能,使普碳钢的力学性能指标由国家标准的Q295级上升到Q390D级.