松软煤层水不耦合装药预裂爆破的力学特性数值分析北大核心CSCD

针对低透气性松软煤层瓦斯难以抽采的现实问题,进行了松软煤层水介质不耦合装药预裂爆破增透的研究。理论上,分析了水不耦合装药爆破在孔壁上形成的初始冲击波压力,并结合断裂力学计算得出煤体中形成的粉碎区和裂隙区范围。同时,利用ANSYS/LS-DYNA三维数值模拟软件,建立了水和空气不耦合装药的松软煤体爆破模型,进行了数值模拟对比分析。研究结果表明:水不耦合爆破后,松软煤体中形成的裂纹数量以及裂隙区范围明显较优,采集到的应力曲线,水不耦合装药爆破后形成的压、拉应力峰值分别是空气不耦合装药爆破的3.71倍和2.58倍;水不耦合装药爆破改善了爆破效果,应用于低透气性松软煤层的预裂爆破增透中,能够有效提高煤层的透气性,抑制瓦斯动力灾害事故。     

松软煤层水不耦合装药预裂爆破的力学特性数值分析

针对低透气性松软煤层瓦斯难以抽采的现实问题,进行了松软煤层水介质不耦合装药预裂爆破增透的研究。理论上,分析了水不耦合装药爆破在孔壁上形成的初始冲击波压力,并结合断裂力学计算得出煤体中形成的粉碎区和裂隙区范围。同时,利用ANSYS/LS-DYNA三维数值模拟软件,建立了水和空气不耦合装药的松软煤体爆破模型,进行了数值模拟对比分析。研究结果表明:水不耦合爆破后,松软煤体中形成的裂纹数量以及裂隙区范围明显较优,采集到的应力曲线,水不耦合装药爆破后形成的压、拉应力峰值分别是空气不耦合装药爆破的3.71倍和2.58倍;水不耦合装药爆破改善了爆破效果,应用于低透气性松软煤层的预裂爆破增透中,能够有效提高煤层的透气性,抑制瓦斯动力灾害事故。     

煤层复合射孔增透技术研究

为增加低渗透高瓦斯煤层的透气性,提高瓦斯利用率和抽采效率,提出复合射孔爆破增透技术。基于弹性力学和断裂力学理论,分别建立复合射孔爆燃气体压裂裂纹的起裂强度因子和裂纹二次扩展半径方程,研究复合射孔爆破增透技术的煤岩裂隙增扩机制;采用FLAC3D有限差分模拟软件分析煤层爆破钻孔内不同长度的裂缝对爆破致裂增透效果的影响,并开展工业试验对比井下复合射孔爆破和常规深孔预裂爆破效果,运用SF6示踪气体研究煤层透气性的变化特征,确定预裂后煤层瓦斯抽采半径。结果表明:复合射孔爆破后煤层透气性与常规深孔预裂爆破相比有显著提高,有效半径可达5m;数值模拟和现场试验结果均证明,采用复合射孔爆破增透煤层能够有效增加煤层透气性,提高抽采率。     

深孔预裂爆破技术在低透气性回采工作面中的试验研究

为解决低透气性回采工作面采煤过程中,瓦斯抽采困难、施工周期长等问题,提出了利用深孔预裂爆破技术,增加煤层裂隙,提高煤层透气性的方法,并研究了深孔预裂爆破技术的作用机理,阐述了深孔预裂爆破技术的工艺流程,对增透效果进行了现场考察.研究表明:深孔预裂爆破后与爆破前相比,平均瓦斯抽采量提高了2.32倍,平均煤层透气性系数提高了5.6倍,最大提高了11.5倍,有效提高了瓦斯抽采率;工作面回采周期大幅度缩短,为安全、快速回采提供了保障.     

深埋突出煤层深孔控制爆破致裂机理和防突效果研究

基于理论分析和数值模拟,探究深孔控制爆破技术在深埋低透高瓦斯煤层防突方面的适用性。考虑爆炸波、爆生气体、煤层原始瓦斯压力、煤层地应力对裂隙的作用。研究深埋低透高瓦斯煤层深孔控制爆破裂隙的扩展的过程、机理及防突效果。对比了理论分析结果和典型的现场试验结果。得出的结论是,煤层深孔控制爆破致裂,是在爆炸波的动态冲击震裂和爆生气体及煤层瓦斯压力的尖劈压裂作用下共同完成的;深埋高应力煤层深孔控制爆破机理与常规浅孔采掘爆破机理不同;控制孔在高应力煤层中的导裂作用并不显著,其主要起到卸压孔和抽放孔的作用。几个典型的高应力低透突出煤层的工程实践表明,采用深孔控制爆破技术后,均获得良好的增透效果,且均未发生煤与瓦斯突出事故。     

高瓦斯低透气性煤层深孔预裂爆破增透技术研究及应用*

为解决高瓦斯矿井开采过程中煤体透气性差、瓦斯预抽周期长、抽采效果不佳的难题,提出利用深孔预裂爆破技术提高煤体裂隙发育度,增加煤体透气性,从而提高瓦斯抽采率的方法。通过现场调研、理论分析、数值模拟及工业性试验等方法,分析深孔预裂爆破卸压增透内在机理,确定爆破影响半径为4.5~5.3 m,并在A110605工作面进行现场应用,同时考察煤层增透效果。研究结果表明:煤层爆破致裂后,平均瓦斯抽采浓度提高了2.17倍,平均瓦斯抽采纯量提高了2.02倍,煤层透气性系数提高了近5.3倍,煤层卸压增透效果显著,很大程度上消除了煤与瓦斯突出危险性,为实现工作面的安全开采及正常接替提供了保障。     

偏心不耦合装药爆炸应力场研究及应用

中深孔光面爆破或预裂爆破质量对永久边坡的长期稳定性与安全性至关重要。利用偏心不耦合装药爆炸应力场的全息动光弹研究成果,对传统不耦合装药结构进行了改进,使高边坡光面爆破或预裂爆破效果得到明显改善,减少了因爆破效果不佳而造成悬、浮石滑落的事故隐患。并在实践中取得了一些有益的经验,可供同仁借鉴。     

五阳煤矿深孔预裂爆破预抽煤层瓦斯的试验研究

为了解决五阳煤矿3#煤层采掘工作面瓦斯涌出量大、瓦斯超限、抽采效果差等问题,提出了深孔预裂爆破预抽煤层瓦斯的治理方法,并在试验矿井7603采煤工作面进行了现场试验;同时确定了五阳煤矿深孔预裂爆破的钻孔布置参数,并对爆破前后的抽采瓦斯浓度、抽采量进行现场考察分析。现场实践表明,深孔预裂爆破能够有效提高煤层的透气性、瓦斯抽采浓度和抽采量,减少抽采时间,为矿井开展深孔预裂爆破预抽瓦斯技术措施提供实践经验和技术支持。     

装药位置对深孔聚能爆破数值模拟与应用研究

为研究不同装药位置对深部聚能爆破增透的效果,构建了不同装药位置的数值模型,运用理论分析、数值模拟和现场应用相结合的方法,分析了深孔聚能爆破不同装药位置周围的应力分布和裂隙发育状态,开展工程试验考察了周围抽采钻孔瓦斯浓度和瓦斯纯量的变化。研究结果表明:不同装药位置相比,中端装药时爆破有效影响范围较大、应力作用时间较长,里端装药时较小,外端装药时最小;聚能爆破中端装药,其爆轰波和应力波作用于煤体的时间较长且应力值更大,爆破产生的裂隙深度主要在轴向上加深,轴向裂隙和径向裂隙比其他装药方式均有增加;爆炸产生的爆生气体与空气波二次作用产生反射波,延长了作用时间,有助于裂隙扩展,加速了赋存瓦斯解吸和流动,爆破效果更好;深部聚能爆破中部装药能够有效地提高煤层的透气性和瓦斯抽采率。     

液态 CO2 相变致裂煤层增透技术布孔方式研究

液态CO2相变致裂技术是一种新颖的低透煤层增透技术。为了更好地将液态CO2相变致裂技术运用到低透气煤层增透领域中,在平煤十三矿进行了液态CO2相变致裂的穿层强化预抽煤层瓦斯现场试验,通过煤层致裂后的瓦斯抽采效果反映出的不同布孔方式下的致裂差异,确定液态CO2的爆破孔的合理布孔方式。现场试验表明液态CO2相变致裂在交错的梅花孔布置方式下由于能量分布均匀,致裂效果优于矩形孔布置方式,研究结果为该技术在煤层增透强化预抽领域的推广应用奠定了基础。     

穿层爆破中控制孔对裂隙扩展作用机理试验研究

为研究控制孔在穿层爆破中对裂隙扩展的作用机理,在实验室内进行穿层爆破相似模拟试验。研究表明:煤岩体试块上表面产生了贯穿炮孔和控制孔的裂隙,侧面生成了多条不规则的裂隙,试块内部出现了包括沿控制孔方向发展的多个断裂面;炮孔和控制孔连线上产生了较高拉应力,炮孔和控制孔连线方向上拉应变峰值是炮孔45°方向上的拉应变峰值的1.12倍;爆破产生的压缩应力波P和在控制孔处反射生成的反射横波Sr、反射纵波Pr在控制孔附近的煤岩体上产生应力叠加,造成煤岩体损伤,最终形成贯穿裂隙。穿层爆破中控制孔对爆生裂隙的扩展起到导向作用,但由于穿层爆破中煤岩交界面的存在,使得应力波出现复杂的反射、透射、叠加效应,造成煤层内裂隙无序发育,工程现场应予以重视。     

石方爆破作业爆破冲击波事故分析

在进行工程爆破时,爆破所产生的飞石、振动、空气冲击波、噪音和毒气是公认的爆破公害,尤其是振动和飞石在爆破过程中是不可避免的危害.针对在实际工程中,由于爆破冲击波造成的人员伤害和设备的损害以及引起该事故发生的危险因素,采用事故树分析方法得到影响顶事件的最小割集,通过计算基本事件的结构重要度,确定了影响爆破冲击波事故的主要因素,并提出相应的安全措施,对降低爆破冲击波效应的影响以及降低露天爆破安全事故有重要意义.     

深孔爆破孔底充填缓冲吸能材料减震试验研究

通过对影响爆破震波各种主要因素的分析,针对深孔爆破采用孔底装填吸能缓冲材料,来削减炸药爆炸在孔底的冲击压力和吸收部分能量,从而达到降低爆破震动对周边建(构)物影响的目的。并进行现场爆破试验,对爆破震动波进行测试,同时对减震爆破装药和非减震的常规爆破装药进行比较,获得的测试数据证明,采用孔底装填吸能缓冲材料其减震率达到3.23%～35.19%。     

Measurement of gas detonation blast loads in semiconfined geometry

The ignition and explosion of combustible vapor clouds represents a significant hazard across a range of industries. In this work, a new set of gas detonations experiments were performed to provide benchmark blast loading data for non-trivial geometry and explosion cases. The experiments were designed to represent two different accident scenarios: one where ignition of the vapor cloud occurs shortly after release and another where ignition is delayed and a fuel concentration gradient is allowed to develop. The experiments focused on hydrogen-air and methane-oxygen detonations in a semiconfined enclosure with TNT equivalencies ranging from 9 g to 1.81 kg. High-rate pressure transducers were used to record the blast loads imparted on the interior walls of a 1.8 m × 1.8 m × 1.8 m test fixture. Measurements included detonation wave velocity, peak overpressure, impulse, and positive phase duration. A comparison of the pressure and impulse measurements with several VCE models is provided. Results show that even for the most simplified experimental configuration, the simplified VCE models fail to provide predictions of the blast loading on the internal walls of the test fixture. It is shown that the confinement geometry of the experiment resulted in multiple blast wave reflections during the initial positive phase duration portion of the blast loading, and thus, significantly larger blast impulse values were measured than those predicted by analytical models. For the pressure sensors that experienced normally-reflect blast waves for the initial blast impulse, the Baker-Strehlow and TNT equivalency models still struggled to accurately capture the peak overpressure and reflected impulse. The TNO multi-energy model, however, performed better for the case of simple normally-reflected blast waves. The results presented here may be used as validation data for future model or simulation development.     

Numerical study of dynamic response and failure analysis of spherical storage tanks under external blast loading

The performance of energy infrastructures under extreme loading conditions, especially for blast and impact conditions, is of great importance despite the low probability for such events to occur. Due to catastrophic consequences of structural failure, it is crucial to improve the resistance of energy infrastructures against the impact of blasts. A TNT equivalent method is used to simulate a petroleum gas vapor cloud explosion when analyzing the dynamic responses of a spherical tank under external blast loads. The pressure distribution on the surface of a 1000 m³ spherical storage tank is investigated. The dynamic responses of the tank, such as the distribution of effective stress, structural displacement, failure mode and energy distribution under the blast loads are studied and the simulation results reveal that the reflected pressure on the spherical tank decreases gradually from the equator to the poles of the sphere. However, the effects of the shock wave reflection are not so evident on the pillars. The structural damage of the tank subjected to blast loads included partial pillar failure from bending deformation and significant stress concentration, which can be observed in the joint between the pillar and the bottom of the spherical shell. The main reason for the remarkable deformation and structural damage is because of the initial internal energy that the tank obtained from the blast shock wave. The liquid in the tank absorbs the energy of impact loads and reduces the response at the initial stage of damage after the impact of the blast.     

深孔预裂爆破在低透性高突煤层中的应用与分析

为提高低透气性高突出煤层瓦斯抽放率,达到预防瓦斯突出的效果,将深孔预裂爆破技术运用于某煤矿低透性高突煤层,考察了这种爆破对煤层透气性系数、百米钻孔瓦斯流量、瓦斯抽放量、抽放浓度、瓦斯抽放率以及突出预测敏感指标的影响。试验结果表明:采用深孔预裂爆破技术后,煤层透气性增强,瓦斯抽放率提高,各项预测指标在回采期间没有出现超标情况,同时也没有发生过瓦斯动力现象和煤与瓦斯突出。     

Attenuation of a point blast shock wave in the dusty air

The behavior of the blast impulse initiated by a point blast in the dusty air is investigated theoretically. It is shown that the jumps of parameters at the shock front in the dusty air follow other regularities in comparison with the case of an ideal gas, beginning from the distance of three dynamic radii, so at ten dynamic radii the difference in overpressure exceeds 60%. When the air heterogeneity is taken into account, substantial gradual changes of wave profile come over and the total blast wave impulse can't be determined by the front overpressure only. The known far asymptotic law takes no place in the point blast flow at the volume dust densities ρ₂₀ > 3·10^?3 kg/m³. In contrast to the ideal gas, the shock front discontinuity vanishes in the dusty air at a finite distance from its origin and the blast wave eventually turns into a dispersive wave without discontinuity. The wave structure changing is studied in the process of the shock wave transformation into the dispersive wave.     

Laboratory scale tests for the assessment of solid explosive blast effects. Part II: Reflected blast series of tests

An experimental set-up has been developed in order to detonate small explosive charges and to measure their induced blast on reduced scale structures. On the basis of Crank Hopkinson’s Law, the results obtained at reduced scale are used to derive full scale predictive models. A previous paper summarized the development of the reduced scale experimental set-up as well as the first free-field tests performed. The main features of the table, the instrumentation and the pyrotechnics were given.The present paper summarizes a second series of tests investigating the validity of models designed to predict reflected blast waves characteristics. Overpressure maxima, arrival time of the shock wave and impulse have been measured and are presented in this paper as non-dimensional characteristics of the pressure-time history. The results obtained from the experiments are in good agreement in comparison with data from the open literature and may thus be considered as reference results for further numerical or analytical model developments.The series of tests reported in this paper is in addition the final series of tests dedicated to validate the experimental set-up and the experimental procedures associated.     

基于微地震监测的华丰煤矿深孔爆破防冲技术

为提高深孔爆破措施对防治华丰煤矿冲击地压的有效性,采用微地震监测技术连续监测其1410工作面围岩破裂情况。根据采场附近岩层"破裂-应力"对应关系,得到工作面前方、侧向及垂直方向上的支承压力峰值区,由此确定深孔爆破卸压的具体参数。结果表明:卸压孔深40 m(倾向投影为4倍采高)时,爆破对煤岩的整体性破坏明显,煤岩体中积聚的弹性能得到释放。监测期间共释放能量9.47 MJ,高应力区向煤岩深部转移,采场附近形成一定的卸载区域,减弱或消除了煤岩体的冲击危险性。