地球物理测井技术在煤矿岩体工程勘察中的应用

在煤矿岩体工程勘察中,地球物理测井技术可以具有广泛的应用,地球物理测井技术包含很多测井技术,其中,较为常用的声波测井技术,本文首先介绍了地球物理测井技术与声波测井技术,然后探讨了地球物理测井技术在煤矿岩体工程勘察中的应用,勘察工程的不同情况,需要不同的地球物理测井技术,并探讨了在使用测井技术过程中需要注意的问题,最后本文介绍了一个地球物理测井技术在煤矿岩体工程勘察中的应用实例。

地下工程岩体结构面的统计与应用研究

以煤矿岩体为例 ,分析了大小规模结构面的相关性 ,提出了地下工程岩体结构面产状的统计方法 ,阐述了多组结构面并存于一岩体时迹线间距的统计与计算方法。并用这些统计参数来确定巷道危石的最大可动区域 ,选择最佳轴线方向 ,为巷道的支护设计提供了科学依据。

分段装药对煤矿岩石爆炸破碎效果影响

为增强深部煤矿岩石爆炸破碎效果,提出了一种分段装药的爆破方法。基于SPH(光滑粒子流)方法,对不同分段比例装药结构下岩体破碎情况、岩石飞散速度以及爆破成腔效果进行了分析,使用分形维数比较了不同装药结构下岩石的破碎效果。研究表明,孔底起爆效果比孔口起爆效果好,普通连续装药结构不能最大化利用爆炸的破岩效果,采用分段装药的方法能为下部岩体破碎增加临空面。当上部装药比例为0.4时,炸药对岩体的破碎效果最好。

Seismic effort of blasting wave transmitted in coal-rock mass associated with mining operation

Microseismic effects during the transmission of seismic waves in coal and rock mass associated with mining operation were studied by on-site blasting tests and microseismic monitoring in LW704 of Southern Colliery,Australia,by using spread velocities,amplitudes and frequency contents as the main analysis parameters.The results show that the average P-wave velocity,mean values of combined maximal amplitudes and frequencies of the first arrivals are all reduced significantly along with goaf expanding and intensity weakening of overlying strata during mining process.A full roof fracturing can make the average P-wave velocities,combined maximal amplitudes and frequencies of first arrivals reduce to about 69.8%,92.2% and 60.0%,respectively.The reduction of the above seismic parameters reveals dynamic effects of the variation of strata structure and property to the wave transmission and energy dissipation of blasting wave.The research greatly benefits further study on stability of surrounding rock under the destructive effort by mine tremor,blasting,etc,and provides experimental basis for source relocation and parameter optimization of seismic monitoring as well.

Dynamic subsidence basins in coal mines based on rock mass rheological theory

In order to investigate the surface deformation caused by coal mining and to reduce environmental damage, more accurate information of dynamic subsidence basins, caused by coal mining, is needed. Based on theological theory, we discuss surface deformation mechanism of dynamic subsidence on the assumption that both the roof and the coal seam are visco-elastic media, put forward the idea that the principle of surface deformation is similar to that of roofs, except for their parameters. Therefore, a surface deforma- tion equation can be obtained, given the equation of the roof deformation derived.from using a HIM rhe- ological model. In the end, we apply the equation of surface deformation as a practical subsidence prediction in a coal mine. Given the theologic properties of a rock mass, the results of our research of a dynamic subsidence basin can predict the development of surface deformation as a function of time, which is more important than the ultimate subsidence itself. The results indicate that using rheological theory to calculate the deformation of a dynamic subsidence basin is suitable and provides some reference for surface deformation of dynamic subsidence basins.

Theory and test research on permeability of coal and rock body influenced by mining

Stress distribution rules and deformation and failure properties of coal and rockbodies influenced by mining were analyzed.Experimental research on permeability of coaland rock samples under different loading conditions was finished in the laboratory.In-situmeasurement of coal permeability influenced by actual mining was done as well.Theoryanalysis show that permeability varied with damage development of coal and rock understress,and the influence of fissure on permeability was greatest.Laboratory results showthat under different loading conditions permeability was different and it varied with stress,which indicated that permeability was directly related to the loading process.In-situ testsshowed that permeability is related to abutment stress to some degree.The above resultsmay be referenced to gas prevention and drainage.

Numerical simulation on pressure-relief deformation characteristics of underlying coal-rock mass after upper protective layer excavation

Based on the occurrence features of Group B coal-seams at a coal mine in the Huainan coal mining area, the elasto-plastic mechanical damage constitutive functions and numerical model for the protective layer excavation were established. With the UDEC2D computer program, after the upper protective layer was mined, the stress field change trends, crack development, and expansion deformation trends of underlying coal rock seams in the floor of the working face were simulated and analyzed. The simulation results show the stress changes in coal rock seams, the evolution process of pre-cracks during the process of upper protective layer mining, the caved zone and fractured zone of the underlying coal rock seams. At the same time, the results from the actual investigation and analysis of protected layer deformation match the simulation values, which verifies the validity and accuracy of numerical simulation results. The study results have an important guiding significance for gas management in low permeability and high gas coal seams with similar mining conditions.

Effect of impulse and bedding on impact toughness of coal

In order to understand the properties of impact toughness of coal at different impact speeds,and the change of impact toughness of lump coal to joint directivity of lump coal,a series of impact tests were conducted on Beijing Da'anshan Lump Coal at different impact speeds and in different impact direction.Through analyzing the test result,it is shown that the change of testing samples is similar when impact is exerted on the vertical bedding and the parallel bedding when the impulse is less than 20 N.s,and the difference increases with the impulse increasing when the impulse is more than 20 N·s.At the same time,the expanding energy of fracture in samples increases with its expanding speed,and the expanding energy of fracture has close relation with the impact direction of the tested samples.And the difference of impact toughness of lump coal produced by different im- pact direction increase with the impact speed.The fracture surface of lump coal when im- pact is exerted on the vertical bedding is smooth and the broken block number is fewer; but the fracture surface of lump coal when impact is exerted on the parallel bedding isn't smooth and the broken block number is more,which inflects impact toughness of coal is sensitive to some deficiency.

Beneficiation of an Indian non-coking coal by column flotation

Beneficiation of non-coking coal is gaining ground in India. It not only reduces the volume of inert content to be transported to the power plant and also lowers the wear in the boiler houses. For special applications such as the fuel for integrated gasification combined cycle plant （IGCC）, the ash content in the coal should preferably be below 15 %. Indian coals are characterized by high inter-grown ash content mainly due to ＇drift origin＇ of Gondwana formation in Permian age. This warrants fine grinding of non-coking coal in order to liberate the ash forming minerals from coal macerals. A non- coking coal sample of vitrinite type from India was ground to 44 ~tm （dso） and subjected to column flotation to improve its quality. The non-coking coal analyzing 34.6 % ash, 26.2 % volatile matter, 1.3 % moisture and 37.9 % fixed carbon could be upgraded to a concentrate/froth of 14.83 % ash at 72.18 % yield by optimizing collector and frother dosages and flotation column operating parameters, namely, froth depth, superficial feed velocity and superficial air velocity. The concentrate produced by this process is suitable as fuel for IGCC in coal-to-electricity route.

STUDY ON SIMULATION EXPERIMENT OF EQUIVALENT MATERIAL APPLIED IN COAL MINE

Based on simulation experiments of a number of scientific research items, the latest progress of experiment method and test technique about equivalent material simulation are introduced. The bevelopment of experiment technique makes analogy simulation evolve into quantitative research about support-surrounding rock relationship from qualitative experiment.From this, large scale stereoscopic simulation experiment is developed, which has never appeared in underground pressure research in China. The present mold specification is 3 - 6 m×2. 0 m ×1. 5 m.