煤材料变形力学特殊分析

在简单压缩实验上获得了煤的应力－应变关系曲线，较好地再了煤的应变强化和应变化软化特性。实验表明煤材料具有典型的弹塑性性质；煤和地壳中其他岩石相比具有一定的特殊性，煤的应力，应变及破坏规律及煤的力学性质有关。     

高煤级构造煤的XRD结构及其构造地质意义

通过１７件构造煤和４件正常煤系列煤样的Ｘ射线衍射分析,深入探讨了构造煤基本结构单元的演化特征及其影响因素,阐明了构造应力作用是促使煤单元面网间距减小和堆砌度及延展度增大的重要影响因素．构造煤镜质组最大反射率与基本结构单元的演化具有良好的相关关系,是煤田构造研究中进行应力－应变分析的重要标志物之一．     

氮化硅陶瓷动态损伤性能研究

利用零普金森杆加载系统对氮化硅陶瓷的动态冲击应力－应变特性作了实验研究，并与氮化硅陶瓷的静态压缩应力－应变特性作了比较，结果表明，氮化硅陶瓷在动态冲击应力作用下，应力－应变关系呈现非线性行为，而在静态压缩应力条件下，应力－应变关系主要表现为准线性行为。     

脉冲电流对Zn－22Al合金超塑性力学行为的影响

本文以普通处理的Ｚｎ－２２Ａｌ合金板坯为对象，研究了脉冲电流对其超塑性力学行为的影响．实验结果表明：在脉冲电流作用下，合金的延伸率和应变速度敏感性指数有了很大提高，流动应力降低．在高应变速率（３．３×１０（－２）ｓ（－１））下，该合金仍具有很高的延伸率．最佳超塑变形温度向低温度方向偏移．合金的超塑变形可在更低温度下进行．     

中碳钢热拉伸流变应力本构模型

为了进一步研究温度和应变速率对固体金属材料的粘性性质及其流变力学特性的影响,在建立20号钢的高温流变应力模型的基础上又对35号、45号碳素钢在温度为450～550℃和等应变速率（0．05～0．2／s）范围内进行了一系列恒温恒应变速率实验,并比较分析了Perzyna模型和Johnson—Cook模型的优缺点,在此基础上提出了一种修正模型,建立了35号钢和45号钢的高温流变应力本构关系,并将模型计算结果与实验结果进行了比较,证实了该模型能更好地描述中碳钢的温度效应和应变率效应．     

散煤的大变形应力应变关系试验研究

为了得到散煤的本构关系,设计了散煤在侧限条件下的大尺寸轴向压缩试验以测定其在轴向分级受压时的应力应变关系,应力和应变的度量分别采用Cauchy应力和对数应变.分析了燃煤的本构关系特点,整理得出:体积应力的对数和体积应变之间近似呈线性关系,偏应力的对数与偏应变之间也近似呈线性关系,此关系符合多孔介质弹性理论中所指出的材料的应力应变关系.基于多孔介质弹性本构模型,通过线性回归分析得到了散煤的体积模量和剪切模量的一般表达式.     

Al-10Sn-4Si合金高温塑性变形的流变应力特征

采用高温压缩试验法,测定了新型Ａｌ－１０Ｓｎ－４Ｓｉ合金高温变形过程的真应力一直应变曲线;在温度为１００－４００℃范围和应变速率为０．０１－１．０ｓ＾－１范围的变形条件下,研究了该合金的流变应力变化规律。结果表明,Ａｌ－１０Ｓｎ－４Ｓｉ合金为正应变速率敏感材料,表现出稳态流变特征：稳态流变阶段,流变应力基本保持不变;稳态流变应力随变速率的增加而增大,随变形温度的升高而降低,进一步分析表明,这种稳态     

三向应力状态下的应力─应变曲线及其应用

应用弹塑性力学的基本原理,推导了由材料单调拉伸应力─应变（σ－ε）曲线求得三向应力状态下应力－应变（σ1－ε1）曲线的表达式。实验结果验证了理论分析结果的正确性,并用σ1－ε1曲线解释了材料在受三向拉应力时机械性能的变化以及带裂纹构件在裂纹扩展时裂纹前缘形状变化的原因。     

三向应力状态下的应力——应变曲线及其应用

应用弹塑性力学的基本原理,推导了由材料单调拉伸应力－应变（σ－ε）曲线求得三向应力状态下应力－应变（σ１－ε１）曲线的表达式。实验结果验证了理论分析结果的正确性,并用σ１－ε１曲线解释了材料在受三向拉应力时机械性能的变化以及带裂纹构件在裂纹扩展时裂纹前缘形状变化的原因。     

铬青铜超塑性压缩试验

对工业用铬青铜ＱＣｒ０．５－０．２－０．１进行了超塑性压缩试验研究,测定了其超塑流变曲线、ｍ值,考察了温度,应变速率对流变应力的影响以及超塑压缩压缩变形后的显微组织。结果表明,７４０－８２０℃,应变速率１．６７＊１０＾－４－１．３３＊１０＾－３Ｓ＾－１的范围内该合金具有较好的超塑性,为其超塑矩形工艺提供了试验依据。     

Creep properties and a creep equation of delay outburst coal and its adjacent mudstone

The study of the creep properties of coal and its adjacent mudstone is very important for understanding the mechanism of delay outburst coal. The samples of delay outburst coal and its adjacent mudstone collected from Yongshanqiao mine were used to carry out triaxial creep tests. The influence of confining pressure and axial compression on the creep test was analyzed. An accelerated creep model was constructed in parallel with a nonlinear viscous component and plastic component. It is connected with the traditional Burges creep model in series. A creep model which can describe the nonlinear viscoelastic-plastic creep model of rock was established and the corresponding creep equation was derived.According to the results of the creep test, the related parameters of the equation were fitted. The results show that, under the same confining pressure, instantaneous creep strain, creep strain of deceleration phase and constant rate creep of the coal and its adjacent mudstone are increased with an increase in the deviatoric stress. But at the same axial pressure, all of the above decrease with an increase of confining pressure. The duration time of the deceleration creep phase increases with the increase in the deviatoric stress. The theoretical values of the creep equation are in good agreement with the experimental results. It indicates that the creep properties of the delayed outburst coal and its adjacent mudstone can be well described by the creep model established in this paper.     

冻融循环作用下煤矸石混凝土的损伤特性及本构关系

考虑煤矸石粗骨料取代率（0、20%、40%、60%）的影响,开展冻融循环试验、单轴受压本构试验及声发射检测试验,研究煤矸石混凝土的损伤本构模型。研究结果表明：不同取代率的煤矸石混凝土的相对峰值应变与冻融损伤值具有较高的相关性,所得冻融损伤值与相对峰值应变的方程可为本构模型的建立提供有效参数。煤矸石混凝土声发射特性与其荷载损伤发展情况、力学性能、应力–应变曲线有紧密联系,基于受压声发射特性,采用PBS平行杆力学模型建立了未冻融循环作用下煤矸石混凝土的荷载损伤模型,并结合其冻融损伤模型,建立了煤矸石混凝土冻融损伤本构关系,计算结果与试验数据符合较好。该模型能较准确地反映混凝土在冻融和单轴受压荷载作用下的全过程损伤特征。     

软煤应变强度硬化冲击灾变

煤与瓦斯突出软煤层不具冲击倾向性,但在深部开采中却发生了软煤层冲击灾变动力现象.为探索软煤冲击灾变的成因,通过文献研究和工程案例实证分析,证明了软煤层冲击灾变现象的客观存在;通过煤样无侧限单轴压缩试验和冲击倾向性测定,得知试验煤样无冲击倾向性,极限载荷后单调应变强度软化;模拟工程背景现场与掘进工作面和采煤工作面中部相同的边界约束和加载条件,开展单自由度边界承压试验,考察灾变全程应力、应变、声发射特征,研究软煤冲击灾变机理.结果表明:单自由度边界条件下加载,3个煤样均出现应变强度软化-硬化-灾变过程,甚至反复软化-硬化;经应变强度硬化,灾变前煤样抗压强度均超过冲击倾向性的阈值条件;定义了应变强度软化、应变强度硬化系数,灾变前应变强度硬化系数分别为1. 26,1. 53,2. 25,应变强度硬化程度比较显著;软煤在单自由度约束条件下承压,应变硬化达到煤样冲击破坏强度条件时,可发生类似硬煤的冲击灾变,合理解释了现场软煤层冲击灾变的成因.深部高应力条件下,煤与瓦斯突出软煤掘进和开采,要对应变强度硬化导致煤层冲击灾变引起重视;工程上,这种冲击灾变的强度一般不高,但其可诱导煤与瓦斯突出或瓦斯异常涌出,危害性很高.     

Rheological behaviors of coal slime produced by filter-pressing

It is an effective way to use coal slime as fuel for circulating fluidized bed boilers, which will not only solve its pollution to the environment, but also turn waste to treasure. In order to provide basic technical information for transportation of coal slime from the coal preparation plant to the boiler, this paper experimentally studied the rheological behaviors of coal slime produced by filter-pressing. By using a rotational viscometer, the influences of water content, temperature, and shear time on the rheological behaviors of coal slime were investigated. Experimental results show that the coal slime will behave like Bingham plastics with low water content and like Bingham pseudo-plastics with 37.5% water content,while like pseudo-plastics with 40% water content. This indicates that the water content of coal slime must be controlled in consideration of both transportation resistance and combustion efficiency. Study results also show that, the apparent viscosity of coal slime at 5℃ is about 1.5–1.7 times of that at 40℃ for water contents 32%–37.5%, while the influence of temperature can be neglected when the water content is 40%. With increasing of water content, the influences of shear time on the apparent viscosity of coal slime becomes less. When the water content is more than 30%, the effect of shear time is negligible. It indicates that water content has the most important influence on the rheological behaviors of coal slime. There must be an optimal water content in considering conveying resistance and combustion efficiency. The environmental temperature must also be considered in coal slime transportation.     

不同煤种地下气化特性研究

在地下气化模型试验及理论分析的基础上，研究了不同煤种的地下气化特性．比较了空气连续气化及纯氧．水蒸汽气化条件下的煤气组成，并从气化煤层升温速率、气化速率、煤气产率、气化效率等方面比较了不同煤种的地下气化特性．试验结果表明，煤种的不同组成决定了空气煤气中CO，H2，CH4含量的不同，鼓风量影响着空气煤气的组成．在适宜的汽氧比条件下，不同煤种纯氧，水蒸汽地下气化均可以获得中热值煤气。对于试验煤种，褐煤具有高的气化活性、气化速率及低的煤气产率，其纯氧-水蒸汽气化效率达87％，最适于地下气化；瘦煤地下气化，气化煤层温度上升缓慢，其气化活性较低，气化速率变化平缓，纯氧-水蒸汽气化效率为74％，但气化过程稳定，且具有高的煤气产率，可以进行地下气化；气肥煤煤层升温速率最快，煤气产率仅次于瘦煤，但在煤挥发分析出后，气化速率减小，气化稳定性变差。     

Experimental study on the deformation behaviour,energy evolution law and failure mechanism of tectonic coal subjected to cyclic loads

Compared to intact coal, tectonic coal exhibits unique characteristics. The deformation behaviours under cyclic loading with different confining pressures and loading rates are monitored by MTS815 test system, and the mechanical and energy properties are analysed using experimental data. The results show that the stress–strain curve could be divided into four stages in a single cycle. The elastic strain and elastic energy density increase linearly with deviatoric stress and are proportional to the confining pressure and loading rate; irreversible strain and dissipated energy density increase exponentially with deviatoric stress, inversely proportional to the confining pressure and loading rate. The internal structure of tectonic coal is divided into three types, all of which are damaged under different deviatoric stress levels, thereby explaining the segmentation phenomenon of stress–strain curve of tectonic coal in the cyclic loading process. Tectonic coal exhibits nonlinear energy storage characteristics, which verifies why the tectonic coal is prone to coal and gas outburst from the principle of energy dissipation. In addition, the damage mechanism of tectonic coal is described from the point of energy distribution by introducing the concepts of crushing energy and friction energy.     

Mechanical behavior of coal under different mining rates: A case study from laboratory experiments to field testing

During deep mining, the excavation disturbance stress path is the domination factor for the stability of the surrounding rock mass as well as the ground pressure. One of the important parameters of the stress path is the loading or unloading rate of the disturbed rock or coal, which depended on the mining rate. To achieve a well understanding of the mining rate and its effect on the coal behavior, a preliminary case investigation of the mechanical properties of the coal at the various mining rates in both the laboratory scale and field scale was performed. Based on the uniaxial compression test and the digital image correlation(DIC) method, the mechanical behavior of the coal samples, such as the evolution of the strength,surface deformation, crack propagation, and elastic strain energy of the coal under the various loading rates were analyzed. A threshold range of the loading rate has been observed. The uniaxial compressive strength(UCS) and releasable elastic strain energy(Ue) increase with increasing loading rate when the loading rate is below the threshold. Otherwise, the UCS and Uemay decrease with the loading rate.Under the low loading rate( 0.05 mm/min), the tensile deformation of the original defects could result in crack coalescence, whereas failure of the coal matrix is the key contributor to the crack coalescence under the high loading rate(greater than 0.05 mm/min). Afterwards, with the consideration of the bearing capacity(UCS) and energy release of the mining-disturbed coal mass(Ue), a power exponential relationship between the mining rate(MR) in the field and the critical loading rate(vc) in the laboratory was proposed. The application potential of the formulas was then validated against the field monitored data.Finally, based on the critical loading rate, the released strain energy, and the monitored pressure on the roof supports, a reasonable mining rate MRfor the Ji 15-31030 working face was determined to be approximately 3 m/d.     

Developing coal burst propensity index method for Australian coal mines

Coal burst is the violent failure of overstressed coal, and it is often accompanied by sound, coal ejection and seismic events. It is subsequently recognized as a serious safety risk of Australia after double fatalities coal burst happened at Austar Coal Mine. Considering the increasing trend of coal burst severity and frequency with mining depth, it is an urgent task to develop the coal burst risk assessment methods for Australia underground coal mines. Coal burst propensity index method is a widely used method of burst risk evaluation of coal as it is summed up from the coal burst research and practice of many countries.This paper presents the experimental and theoretical research of coal burst propensity index method for coal burst risk assessment in Australia. The definition of four indexes including elastic strain energy index(W_(ET)), bursting energy index(K_E), dynamic failure time(DT) and uniaxial compression strength(RC)is introduced in the first part. Then, the standard laboratory test process and test parameter of coal burst propensity index is presented. DT test is conducted with 0.3 mm/min displacement control loading rate while other test is with 0.5 mm/min. Besides, modified data processing and risk classification method of test are proposed. Differentiate analysis of stress-strain curve is adopted in the data processing of DT and KEindex. A four level risk classification form of burst risk is recommended for Australian underground coal mines. Finally, two likely improvement methods of W_(ET) test, including volumetric strain indicator method and theoretical calculation method, are discussed.     

巨厚砾岩层下综放采场矿压显现规律

巨厚砾岩层下综放采场矿压显现规律研究对于采场围岩控制和安全生产具有重要的现实意义.采用理论分析和义马矿区千秋煤矿矿压观测方法进行研究,得出结论为:综放工作面围岩可控程度属于难控围岩,即采场顶底板围岩控制困难.选出了ZF7000-18/28型放顶煤基本支架及其综放面合理配套设备;现场观测研究了综放面矿压显现规律,得出了采场顶板来压步距、来压强度等参数.采场矿压显现明显,不同区域来压具有不一致性.顶板周期来压时支架循环末工作阻力最大值为4 307.70 kN,为支架额定工作阻力的61.54%.因此,采场支架可靠性能较高,现场应用试验效果显著,矿井实现了"一井一面"生产模式,推动了安全高效矿井建设.     

Application of PCC pile in soil improvement of highway

The construction process and load-bearing behaviors of Cast-in-place concrete thin-wall pipe piles are analyzed based on its application on Yantong Expressway Project. The low strain test, static load test and field excavation were also carried out, and the bearing capacity of the new pile can meet the requirements of design. With the increase of pile diameter, the bearing capacity is increased. The settlement of composite foundation is decreased, when the replacement ratio of pile is increased. The test re...