高温后大理岩各向异性响应特征研究

通过对含层理大理岩开展经历不同温度后的纵波波速测试试验,分析高温作用后大理岩纵波波速的变化规律,在此基础上探讨各向异性指数(平行与垂直层理方向波速比值)的变化趋势,研究温度对大理岩各向异性的影响规律。研究结果表明:经历高温后大理岩纵波波速下降,而且随经历温度的升高,大理岩纵波波速持续降低;大理岩纵波波速存在层理效应,主要表现为平行层理方向的波速大于垂直层理方向波速,各向异性指数为1.11~1.19;在30~200℃范围内,大理岩各向异性指数随温度呈现出两边低中间高的"倒U"形变化规律。研究成果在一定程度上反映了经历高温后岩石各向异性的变化,为预测和评估高温工程围岩的长期稳定性和安全性提供理论基础。     

温度对大理岩力学性能的影响

采用RMT-150C岩石力学试验系统开展不同温度作用（20、200和800 ℃）下大理岩的单轴、三轴试验及温度循环作用后大理岩的单轴压缩试验,系统地分析了大理岩在不同温度以及温度循环作用下的物理力学特性。试验结果表明：随着温度的升高,大理岩的变形特性表现为塑性变形明显、弹性模量降低、峰值应变增大。和常温下试件相比,加热到200 ℃后,试件的黏聚力提高,内摩擦角降低;加热到800 ℃后,试件的黏聚力降低,内摩擦角基本相同。在200 ℃循环作用下,随着作用次数的增加,大理岩试件的峰值强度、弹性模量均呈现出降低的趋势。随着温度的升高,大理岩的纵波波速发生不同程度的降低;与单次加温相比,随着循环加温次数增多,纵波波速降低,但是降低幅度很小。常温以及200 ℃温度作用下,试件的破坏基本为宏观单一断面的剪切破坏; 800 ℃高温作用下,部分试件产生了很多条破裂面;温度循环作用对岩石试件破裂形式没有显著影响。     

高温循环加卸载作用下砂岩力学性能弱化及超声规律研究北大核心

为探索煤层气顶部岩石在高温与循环加卸载后力学性质弱化的规律,采用DDL-200单轴电子试验机对岩石进行分级循环加卸载试验,分析了力学参数、波速传播等弱化规律。结果表明:在25~400℃不同应变增量较小,形态破坏为劈裂破坏且内部损伤不均匀,纵波波速传播快;在400℃后应变增量大,破坏形态主要为剪切破坏,内部碎屑增多孔隙变大,岩石外层断裂面多而不规则,纵波波速慢;软化系数在加载期,同循环下随温度升高而减小,同温下随循环增多而变大,劣化度在加载期,同循环下随温度升高而降低,同温下随循环增加先变大后减小;在卸载期,软化系数与劣化度都随同循环(或同温下)升高而增大。     

高温后粗砂岩弹性纵波波速的试验研究

对粗砂岩经历不同高温后弹性纵波波速进行了相关研究.分析了粗砂岩波速与温度的变化规律.总体上随着加热温度的升高,粗砂岩弹性纵波波速处于单调下降的趋势.试验结果表明,粗砂岩作为高空隙度岩石,加热温度小于100℃时,弹性纵波波速变化不明显;而当加热温度超过100℃后,弹性纵波波速大致成线性降低,波速与温度具有良好的相关性.     

冻融循环对饱水岩石纵波波速影响的试验研究

为探究冻融作用对饱水岩石纵波波速与损伤变量的影响规律,在冻结温度为-20℃、融解温度为20℃的条件下,对饱水砂岩、黑云变粒岩、闪长岩和灰岩开展了40次的冻融循环试验。结果表明:在相同的冻融条件下,岩石的矿物成分、胶结类型、孔隙特征、矿物颗粒的排列方式对岩石的纵波波速和损伤变量均产生重要影响;经历40次冻融后,砂岩、黑云变粒岩、闪长岩和灰岩的纵波波速较饱水岩样分别降低了42.12%、14.30%、23.21%和19.24%;纵波波速和损伤变量降低幅度在前5个冻融周期降低较为明显,随冻融次数的增加,纵波波速与损伤变量的降低幅度逐渐减小并趋于稳定。     

不同高温循环作用后砂岩动力特性试验研究

煤炭地下气化过程中围岩将经历高温作用,且爆破等扰动荷载进一步加剧了深部工程灾害的频发可能和预测难度.为研究温度效应对高温循环作用后岩石动力特性的影响规律,对常温(25℃)和经历200～1000℃高温循环作用后的砂岩试件进行基本物理参数测试,利用SHPB试验装置开展冲击压缩试验,并借助高速摄像机观察试件变形破坏过程.结果表明:常温砂岩为灰白色,随循环作用温度升高颜色逐渐变为青灰色;不同高温循环作用后试件质量、密度和纵波波速等变化率均与循环作用次数呈二次函数关系.随循环作用温度升高,试件动抗压强度、动弹性模量呈二次函数关系降低,动应变呈线性关系增大,且动抗压强度和动应变均在400℃前后变化幅度有所不同.试件变形破坏主要是沿加载方向率先萌生裂纹,周边碎块逐渐脱落飞出,呈剥落式破坏模式;试件受冲击荷载作用的破碎程度随循环温度升高而加剧,碎块平均粒径与循环作用温度呈二次函数关系减小趋势.     

冻融循环条件下岩石物理力学指标相关性分析

为了得到冻融循环条件下岩石强度指标与物理指标的关系,在室内实验和理论分析的基础上,建立了冻融循环过程中岩石抗压、抗剪强度力学指标与纵波波速、孔隙率物理指标的关系。试验结果表明:随着冻融循环次数的增加,岩石的孔隙率增大,纵波波速、单轴抗压强度、弹性模量、黏聚力降低;冻融循环条件下粗砂岩的孔隙率、纵波波速与单轴抗压强度、弹性模量、黏聚力之间具有良好的相关性。通过测量经历不同冻融次数的岩石的孔隙率和纵波波速,较好地反映出冻融循环过程中岩石强度的衰减关系。     

单轴加载条件下大理岩的实时轴向波速变化特征与频谱分析

为研究大理岩在单轴应力条件下的实时轴向波速的变化特征,采用自主研发设计的超声波检测替代承压装置,完成了大理岩、Q345钢的单轴压缩试验与实时轴向超声波测试,并结合FFT方法分析了大理岩试样与Q345钢试样的波速、频谱特征。试验结果表明:在单轴加载条件下,Q345钢试件耦合面的接触性状是导致其波速增长的主要原因,而大理岩纵波波速随应力的变化则受耦合面接触性状与孔隙闭合特征的共同控制,大理岩在弹性范围内的波速变化可分为孔隙压密段与线弹性段两个阶段;试件端面接触性状越稳定,波速增长越慢,波速越高,次频带谐波能量越低;随着岩石内部的孔隙、裂纹被压密,纵波波速增大,频域信号的低频段能量逐渐向高频段转移。     

类岩石锚固体单轴抗压强度与声波波速的相关性

类岩石锚固体声波波速与其强度特性的研究较少,针对类岩石锚固体试样制作的特殊性,结合室内单轴压缩试验,利用声波测试技术分析类岩石锚固体单轴抗压强度与声波波速的关系特点.无论标准试样有无锚固或相似原料配比变化,纵波波速增大,单轴抗压强度也相应随着增大.锚杆轴向布置和横向布置均能提高试样的单轴抗压强度,但提高的幅度很相近,这可以通过两种加锚方向的试样纵波波速变化不大来反映.对比类岩石锚固体试样单轴抗压强度随试样密度和纵波波速的变化关系,纵波波速的影响更显著.     

高温环境下大理岩热损伤特性的试验研究

采用MTS 810电液伺服材料试验系统对常温~800℃高温作用下大理岩的力学性能进行了研究,考察了大理岩的全应力-应变曲线、峰值应力、弹性模量等量的变化特征.结果表明:随受热温度升高大理岩的峰值强度和弹性模量不同程度上渐次降低,尤其是在不同温度段岩石强度降低具有突变性,800℃时大理岩的延性明显增强.基于岩石的应变强度理论和岩石强度的随机统计分布假设,采用损伤力学理论,考虑微元体破坏及弹性模量与温度之间的非线性关系,建立了单轴压缩下的大理岩损伤统计本构模型,给出了考虑温度效应大理岩损伤统计本构模型参数.通过与高温状态下单轴压缩实验结果相比较,显示了所建模型的合理性。最后探讨了温度对大理岩损伤特性的演化规律.     

Market and recycling of NiMH battery

<正>Market status and future trend of NiMH battery1.Global market of small NiMH battery Global market size of small NiMH batteries declined year on year since 2011.The trend will continue to 2018,at the rate of 5%to 10%annually.Demand for small NiMH batteries will be stable gradually.Many electrical apparatuses are powered by the built-in lithium battery today,which is the main reason for the shrunk market of small NiMH batteries.But,for some products,small NiMH     

China rare earth market review

正September 1-10,2014 Affected by the National Day holiday,rare earth transaction was stagnant and the market showed a weak steady state.As there was no good news for downstream market,some products with flat demand would likely rally slightly for some time to     

Current situation and future trend of China rare earth luminescent materialindustry(continued)

<正>Developing ecological lighting source The world is facing the big problem of energy shortage today and the contradiction between economy development and environmental protection is worsened.Therefore,people are more likely to choose an ecological light source that is more energy efficient and environmental friendly.The choice provides great opportunity for the development of rare earth optical material industry in China.The concept of green lighting positions rare earth luminescent material as a leading player in illumination market.The light source of both rare earth luminescent lamp and LED lamp is ecological and energy saving.This is why     

Galaxy Magnets achieved the net profit of 34.02 million yuan in the first six months of 2014

正Galaxy Magnet announced its financial results for the first half of 2014 on August 14.For the first six months ended on 30 June 2014,Galaxy Magnet achieved operation income of RMB 182.3 million,up8.40% over the same period of 2013,and the net profit attributable to the shareholders of the listed company of 34.02 million yuan,increasing 35.49% over the same period of last year.Stable performance increase was led by development of new customers and application market of magnets.     

Rare Earth Application in Steel in China

<正>China has rich rare earth resources.Output of rare earth and steel in China ranks the top first in the world.However,there is still certain distance between the steel produced in China and developed countries from the point of varieties and quality.China still has to import some types of steel.Improving the quality should be emphasiZed in future development of steel industry in China.Rare earth can be used to upgrade traditional steel     

China rare earth market review

正November 21~30,2014Due to weak demand from downstream industries,transactions of rare earth in Chinese domestic market were inactive.It was difficult to sell any rare earth products except for dysprosium oxide and terbium oxide.Suppliers lost confidence in recent market.Demand for rare earth products was soft.Consumers continued to take a wait-and-see attitude.Rare earth export market remained slow.     

稀散金属产业的观察与思考

分析了近年来国内外稀散金属产业的生产、应用、资源与市场状况.铟锡氧化物靶材、砷化镓晶片、锗红外材料、铼高温合金和硒在电解锰及玻璃的应用等已成为稀散金属的主要应用领域.稀散金属的产量快速增长达到历史高位而导致了市场的失衡.以GaInP_2/GaAs/Ge,CIGS和CdTe为代表的非硅系太阳能电池是稀散金属的新兴应用领域,将给稀散金属带来日益增长的需求.     

Current situation and future trend of China rare earth luminescent material industry

<正>Rare earth luminescent material is one of the most important application sectors of rare earths.China enjoys the exceptional advantage to develop rare earth luminescent material for its abundant rare earth resources.After several decades'endeavor,China's rare earth luminescent material industry,headed by rare earth phosphor for lamp and LED and high efficient rare earth energy-saving light source,has been gradually developed into a scale industry.China has become a major production base of rare earth phosphor for lamps and rare earth     

China rare earth market review

正June 1~10,2014Rare earth market remained weak.Quoted price of rare earth products was similar to that in May.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,polishing powder and ceramic industries remained inactive.Demand from downstream industry was soft.Consumers purchased on their needs.Suppliers had strong intention to sell.Prices of rare earth products     

2014 second batch of rare earth quota released

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