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351.
基于激波理论的新兴煤矿煤与瓦斯突出事故研究 总被引:1,自引:0,他引:1
通过分析新兴煤矿煤与瓦斯突出事故,发现在事故中由于煤与瓦斯突出事故诱发了激波的生成,瞬间产生的巨大超压,引起风流逆向,大量瓦斯随逆向风流从突出地点扩散传播至二水平,接触卸载巷电机车架空线所产生的电火花,从而引发瓦斯爆炸事故。提出了突出激波对事故的影响并分析了突出激波的形成及其破坏作用,研究了影响突出激波破坏作用的影响因素,得出参与突出的瓦斯量和瓦斯压力是影响激波强度的关键因素。有助于了解突出后的气流动力演化规律,并为煤与瓦斯突出事故的防灾、救灾措施的制定以及提高矿井的抗灾能力提供了参考。 相似文献
352.
A laneway support system provides an available way to solve problems related to ground movements in underground coal mines, but also poses another potential hazard. Once a methane/air explosion occurs in a laneway, inappropriate design parameters of the support system, especially the support spacing, likely have a negative influence on explosion disaster effects. The commercial software package AutoReaGas, a computational fluid dynamics code suitable for gas explosions, was used to carry out the numerical investigation for the methane/air explosion and blast process in a straight laneway with different support spacing. The validity of the numerical method was verified by the methane/air explosion experiment in a steel tube. Laneway supports can promote the development of turbulence and explosion, and also inhibit the propagation of flame and shock wave. For the design parameters in actual laneway projects, the fluid dynamic drag due to the laneway support plays a predominant role in a methane/air explosion. There is an uneven distribution of the peak overpressure on the same cross section in the laneway, and the largest overpressure is near the laneway walls. Different support spacing can cause obvious differences for the distributions of the shock wave overpressure and impulse. Under comparable conditions, the greater destructive effects of explosion shock wave are seen for the laneway support system with larger spacing. The results presented in this work provide a theoretical basis for the optimized design of the support system in coal laneways and the related safety assessments. 相似文献
353.
Rockburst hazard determination by using computed tomography technology in deep workface 总被引:8,自引:0,他引:8
The rockburst in mines results from the dynamic load coupled with static one in coal seams around workface zones, so it is essential to learn the stress distribution of the coal and surrounding rock for determination of rockburst risk areas. The relationship between the elastic wave velocity and stress applied on coal sample was investigated systematically by laboratory testing, theoretically analysis, as well as on-site observation, and a positive correlation between them under uniaxial compression was put forward. Furthermore, it is drawn that the anomaly of elastic wave velocity reflects the stress changes: the positive anomaly ascertains the stress concentration while the negative anomaly estimates the mining destress and weaken degree, and corresponding assessment criterions and parameters were established respectively. The hazard areas and degree of an island longwall face 16302C were forecasted before coal winning based on the elastic wave anomaly distribution rules using active tremor velocity inversion, monitoring results of mining shocks during exploitation indicate that the consistency between locations of big tremors and where forecasted by computed tomography (CT) exceed 80%. The successful application of this technology achieved remarkable economic and social benefits for disaster control in rockburst mines. 相似文献
354.
Marzieh Mokarram Hamid Reza Pourghasemi Huichun Zhang 《Frontiers of Environmental Science & Engineering》2020,14(6):114
355.
Explosions often lead to destruction of equipment, which is a difficult problem including complicated fluid-solid interactions. Most traditional CFD methods cannot synchronously solve the movements of fluids and large deformation and fracture of solids because such problem is usually accompanied with constantly moving-and-changing boundary conditions. In this paper, a coupled Finite Element Method-Smoothed Particle Hydrodynamics (FEM-SPH) method was proposed to simulate the dynamic processes of explosions in pipes. The propagation of blast wave and the fracture of pipe were captured in every timestep, where the energy dissipation caused by plastic deformation and crack propagation were fully considered. A rate-dependent failure criterion for high-strain-rate load conditions was employed in the numerical simulation, which was presented in our previous work and has been verified in the dynamic fracture behavior of steels for pressure vessels and pipes. In addition, a simpler formula was proposed to describe the attenuation of blast wave outside the pipe and the consequences caused by the explosions were assessed. Results revealed the interaction between blast wave and pipe, the leakage of detonation products, the attenuations of peak overpressures outside the pipe and the corresponding consequences at different distances. It is found that when considering the energy consumption during plastic deformation and crack propagation in coupled FEM-SPH method, the assessment results are more rational than that without considering such energy consumption. 相似文献
356.
357.
Jinqiu Hu Laibin ZhangWei Liang 《Journal of Loss Prevention in the Process Industries》2011,24(4):449-457
In the long distance pipeline remote monitoring system, small leak detection becomes an important issue. Weak singularities in small leak signals are usually difficult to detect precisely under complicated noise background, which may cause false alarm or miss alarm. The advantage of applying the harmonic wavelet method is explored in this paper. Pipeline small leak sensitive characteristics are recognized and the negative pressure wave inflexions are extracted by harmonic wavelet analysis, expressed in terms of harmonic wavelet time-frequency mesh map, time-frequency contour map, and time-frequency profile plot. This paper also presents a comparative study of both Daubechies wavelet and harmonic wavelet analysis when applied to pipeline small leak detection under complicated background noises. Results of simulating test and field experiment show that it is possible to distinguish weak non-stationarities from complicated noises by harmonic wavelet analysis in pipeline small leak detection system. The comparison clearly illustrates that harmonic wavelet based pipeline small leakage detection method is significantly more accurate than other wavelets analysis such as Daubechies wavelet. This work provides a reliable and safe guarantee for oil and gas long distance transportation, reducing petroleum product losses and protecting surrounding environment. 相似文献
358.
本文给出了微振动台阵的波长与台站对间距离的半理论-半经验关系;根据前人的理论和实验,指出微振动波场存在优势方向,即在有效波长范围内,微振动的各道记录存在相位差;提出了投影到某方位的相位校正公式和校正方法,由此实现空间自相关法的相关函数和相速度曲线的时间延迟校正,通过实例验证了该方法的有效性. 相似文献
359.
360.
Batch mode experiments were conducted to study the removal of hexavalent chromium(Cr(Ⅵ)) from aqueous solutions using ultrasound-assisted aqueous solution ball milling.The results show that the reduction rate of Cr(Ⅵ) by ultrasound-assisted aqueous solution ball milling was significantly faster than that by ball milling or ultrasound treatment alone,and an initial Cr(Ⅵ) concentration of 166 mg/L could be decreased to 0.35 mg/L at 120 min.The decisive factors, including initial concentration of Cr(Ⅵ), p H value, ultrasonic frequency and filling gas, were studied. It was found that the optimal ultrasonic frequency for ultrasound-assisted aqueous solution ball milling device was 20 k Hz, and the rate of Cr(Ⅵ)reduction as a function of filling gas followed the order: Ar air N_2 O_2. Samples were characterized by X-ray diffraction, fluorescence measurements, atomic absorption and the diphenylcarbazide colorimetric method. The Cr(Ⅵ) transformed into a precipitate that could be removed from the contaminated water, after which the water could be reused. 相似文献