深层煤矿床的煤岩样物性测试结果与分析

对深层煤矿床的钻探岩芯、井下样本进行了实地采集,并在实验室利用超声波技术对深层煤矿床进行了常规条件、加压、水饱和、高温等不同条件下的纵横波速度测试,结果表明:压力对煤岩样的超声波速度、波形和频谱有较大影响,加压使纵横波速度均有不同程度的提高,且纵波速度增幅值比横波快;水饱和也使纵横波速度值有所增大,但增加幅度没有压力显著;温度的变化对速度的影响不甚明显。

超临界CO_2与煤中矿物的流固耦合及其地质意义

针对超临界CO2与煤中矿物反应改变煤岩物性、影响CO2驱替煤层气开采的现状,介绍了超临界CO2与矿物碳酸化反应的基本原理,评述了煤中矿物碳酸化过程对煤岩物理性质的改造作用。基于前人研究成果,指出现有实验室模拟与地质条件下煤中矿物碳酸化过程存在很大差异,认为地质条件下超临界CO2与煤中矿物的流固耦合机理严格受控于煤岩的孔裂隙系统,指出超临界CO2与煤中矿物流固耦合作用对矿物形态与结构及煤岩力学性质、表面电性、吸附性等的改造有待进一步认识。并指出煤岩结构的完整性和弱水动力条件是建立合理煤中矿物碳酸化过程及效应的基础。

Preparation and coking properties of coal maceral concentrates

The concentrates with different maceral contents were obtained from Kailuan coking coals with different coal ranks(Ro;ranvarying from 0.88%to 1.73%)by float–sink separation in lab.Then these concentrates were characterized by proximate analysis,ultimate analysis,petrography analysis and coking index determination.The results show that the vitrinite is characterized as nature of lower carbon content,higher hydrogen content,higher volatile matter and stronger caking property compared to inertinite.The relationships between variation rate of volatile matter and maximum volatile matter and coal ranks are identified,and a linear model is developed for fast determination of the maceral contents.Compared to inertinite-rich concentrate,the blending ratio of vitrinite-rich concentrate is increased by 13%,which is considered to be a potential technique based on maceral separation for expanding the coking coal resources.

Settlement behavior of coal mine waste in different surrounding rock conditions

In order to investigate the influence of complex conditions of in-situ surrounding rocks on the settlement behavior of nubbly coal mine waste subjected to high gravity pressure,four kinds of loading chambers made of different similar materials with different elastic moduli in experiments were used to simulate the deformation features of in-site rocks,including soft,moderate hardness,hard and extra-hard rocks. The results show that all the settlement-axial load (or axial strain-stress) curves obtained under four different surrounding rock conditions present power-exponential function feature. The final settlement of coal mine waste under the same axial load is closely related to the lumpiness gradations and the deformation behavior of chamber materials used to simulate behaviors of different in-situ surrounding rocks. In the same surrounding rock condition,the final settlement under the same maximum axial load decreases with the decrease of the proportion of larger gradation of coal mine waste. While for the same lumpiness gradation case,the settlement increases with the decrease of elastic modulus of simulated surrounding rocks and the lateral pressure induced by axial load increases with the increase of elastic modulus of loading chambers that are used to simulate different surrounding rocks. The test results also reveal that both the compaction curve and lateral pressure curve show a three-stage behavior,and the duration of each stage,which is closely related to gradations and the deformation feature of loading chamber materials,decreases with the increase of the proportion of the small size of coal mine waste and elastic modulus of the simulated rock materials.

Effects of thermal treatment on physical and mechanical characteristics of coal rock

To study the physical and mechanical properties of coal rock after treatment at different temperatures under impact loading, dynamic compression experiments were conducted by using a split Hopkinson pressure bar(SHPB). The stress–strain curves of specimens under impact loading were obtained, and then four indexes affected by temperature were analyzed in the experiment: the longitudinal wave velocity, elastic modulus, peak stress and peak strain. Among these indexes, the elastic modulus was utilized to express the specimens' damage characteristics. The results show that the stress–strain curves under impact loading lack the stage of micro-fissure closure and the slope of the elastic deformation stage is higher than that under static loading. Due to the dynamic loading effect, the peak stress increases while peak strain decreases. The dynamic mechanical properties of coal rock show obvious temperature effects. The longitudinal wave velocity, elastic modulus and peak stress all decrease to different extents with increasing temperature, while the peak strain increases continuously. During the whole heating process, the thermal damage value continues to increase linearly, which indicates that the internal structure of coal rock is gradually damaged by high temperature.