等值反磁通瞬变电磁和微动法在内蒙古某萤石矿采空区探测中的应用效果浅析

萤石矿老旧采空区是矿石资源二次开发利用过程中常见的不良地质体,物探是采空区勘查的重要手段,等值反磁通瞬变电磁法和微动勘探在采空区的勘察中应用广泛。本文通过等值反磁通瞬变电磁法和微动勘探两种方法在内蒙古某萤石矿采空区进行探测,结合已知矿体分布情况,建立了研究区200 m以浅的电性结构,划分了采空区顶板、底板和边界范围,推断了采空区的空间展布情况,为矿区现有萤石矿储量计算及资源二次开发利用提供了参考依据。两种方法推测结论基本一致,采空区和断裂异常反映略有不同,钻孔验证结果表明,等值反磁通瞬变电磁法及微动勘探两种方法均能反映采空区形态、厚度、埋深等空间分布特征,为采空区边界的详细划定提供依据。等值反磁通瞬变电磁法仪器轻便,采集时间短,受地形限制小,大大提高了野外的施工效率,是采空区勘查中物探首选方法;不足之处是微动勘探在草原、戈壁等相对震源较少区采集数据较慢。     

煤矿塌陷区桥梁地基稳定性研究

新建邢都公路栾卸大桥部分桥墩位于废弃小煤矿采空区之上 ,在大桥荷载作用下 ,采空区上覆岩层和地表可能重新移动 ,引起大桥地基的移动、变形和破坏 ,危及大桥的安全 .据物理勘探的结果 ,确定了采空区的范围 ,分析了大桥荷载对采空区煤柱的影响 .在充分论证的基础上 ,提出了加固大桥地基的技术措施 ,对于类似问题的解决具有一定的借鉴意义 .     

综合物探技术在煤矿采空区探测中的应用研究

以煤矿采空区探测为背景,将高密度电法和瞬变电磁法相结合。采用不同装置,对所建立的典型地电模型数值模拟,得到正演数据,然后再进行反演计算,将反演结果与实际情况进行对比、分析,最终得出探测煤矿采空区的最佳组合。研究认为：偶极一偶极装置是最佳装置,适合勘探深度小于100m的采卒区,其他四种勘探装置各有优缺点,可根据不同的地质情况进行选择;中心回线装置效果最好,但是勘探深度有限,适合稍浅采空区的探测,但是工作效率太低。综合考虑,大定源回线装置更适合煤矿采空区深部探测,而且工作效率更高。将偶极一偶极和大定源回线装置应用于某地区煤矿采空区探测中,高密度电法能够清晰的探测出80m以内的地层情况,划定采空区范围,后经钻探验证,证明推断正确;瞬变电磁法能够探测出200m以下的采空区情况,推测出一个采空区位置。后经钻探验证,证实推测。说明,利用高密度电法和瞬变电磁法综合地球物理勘探,是可行的,也是有效的。     

Tsikl-7瞬变电磁系统在宝日希勒露天矿采空区探测中的应用

应用Tsikl -7瞬变电磁系统对宝日希勒露天矿测区内采空区的分布情况进行了勘探,确定了采空区的分布范围并提供钻探位置.矿方对探测成果进行验证,并在打钻位置予以爆破,地表均有采空区塌陷.验证结果表明应用Tsikl -7瞬变电磁系统并选取合理的施工参数能有效探查该露天矿采空区的分布范围,有力地指导露天矿回采剥离工作的顺利...     

小线圈瞬变电磁法在煤层采空区探测中的应用

在黄土梁峁地貌进行采空区勘探,在目标煤层的埋藏深度已知的条件下,有效、快速地找出其位置,笔者选用瞬变电磁法,通过试验,选择1.5m×1.5m的重叠回线装置,在勘探区内区进行采空区探测.然后再结合区内的地质条件进行分析和解释工作.探测结果表明:瞬变电磁法探测采空区准确可靠,证明小线圈装置施工效率高、效果好.     

综合物探在山西省某煤矿采空区探测中的应用

为充分发挥物探方法在探测地下采空区的优势,查明山西省灵石县英武乡某煤矿地下采空区分布。根据测区场地条件,本文提出了地震勘探和氡气测量相结合的综合物探方法,利用反射波地震勘探的多次覆盖技术具有较高的探测精度,既能准确查明地下采空区分布的优势,又可弥补氡异常无法判断裂隙带产状及其地下延伸情况的不足;利用氡气测量受地形影响小、可准确圈定采空区边界和断裂构造位置的优势等优点,既可对地震勘探成果起到佐证作用,又可避免或减少其多解性。从而实现两种物探方法的优势互补作用,取得了较好的探测效果,该组合模式可为同类场地条件下探测地下煤层采空区提供有意义的借鉴。     

双源面波地震勘探在煤层采空区探测中的应用

面波勘探具有简便、快速的优点,在陕北柠条塔井田煤层采空区探测中取得良好的地质效果。利用面波的特征反映不仅可以通过单炮记录进行煤层采空区初步解释,还可通过剖面波场特征频谱特征以及频散曲线进行煤层采空区综合解释。     

α卡法和高密度电法在采空区探测中的应用

在治理采空区塌陷等地质灾害时,采空区位置的探测显得尤为重要。根据采空区和围岩间的导电性差异,结合地质资料,采用α卡法和高密度电法相结合的综合地球物理勘探方法,开展采空区位置的探测研究。研究表明:未充水的采空区出现α射线强度脉冲读数和视电阻率异常高值是探测采空区的地球物理前提条件;利用α卡法和高密度电法相结合的手段对采空区进行探测,效果良好,结论可靠。     

地震勘探技术在解释地质异常体的应用分析

地震勘探技术在控制煤层赋存形态方面有高于其它物探方法的优势,尤其在准确圈定小窑采空区、岩浆岩侵蚀、煤层露头、火烧区及冲刷带、陷落柱等地质异常体方面已取得了很好的效果,对煤矿产业的生产和建设都起到了举足轻重的作用。本文通过河北、新疆和山西等地煤矿采区三维地震勘探实例介绍了如何根据地震时间剖面表现的不同特征来确定和解释各种煤层地质异常体,并取得了良好的地质成果。     

综合物探方法在大宝山矿采空区勘察中的应用效果探讨

矿山的采空区,尤其是不明采空区对矿山的采矿施工构成严重的安全隐隐,对矿山的不明采空区进行全面勘查是保证矿山安全的重要手段。本文通过大宝山矿已知采空区和勘查区的几种物探方法的测量结果,提出了高密度电法和浅层地震纵波反射法对采空区的勘查具有较好的勘探效果。通过对物探成果资料和地质资料的对比研究,总结了采空区异常的识别方法,最后总结了各种方法的优缺点,提出了今后对采空区勘查工作方法的建议。     

Computational fluid dynamics simulation on the longwall gob breathing

In longwall mines, atmospheric pressure fluctuations can disturb the pressure balance between the gob and the ventilated working area, resulting in a phenomenon known as ‘‘gob breathing". Gob breathing triggers gas flows across the gob and the working areas and may result in a condition where an oxygen deficient mixture or a methane accumulation in the gob flows into the face area. Computational Fluid Dynamics(CFDs) modeling was carried out to analyze this phenomenon and its impact on the development of an explosive mixture in a bleeder-ventilated panel scheme. Simulation results indicate that the outgassing and ingassing across the gob and the formation of Explosive Gas Zones(EGZs) are directly affected by atmospheric pressure changes. In the location where methane zones interface with mine air, EGZ fringes may form along the face and in the bleeder entries. These findings help assess the methane ignition and explosion risks associated with fluctuating atmospheric pressures.     

Method of calculation of a methane concentration field in gob areas with a known velocity field based on the model of stream tubes

The control equations of gas concentration field in gob areas with a known velocity field are partial differential equations with variable coefficients, whose traditional mathematical calculation methods are very complex. A numerical simulation method can be used to calculate the gas concentration field, but it also needs considerable amounts of computer resources and the relations of gas concentration at different points of the gob area are undefined. Based on the model of stream tubes, the conservation equations of mass and gas components within the stream tube are used to deduce the equations of a gas concentration field in a gob area with a known velocity field. This method of calculation of a gas concentration field is applied in a gob area with a U-type ventilation working face, which suggests that this new method has the virtue of exact calculations is simple to operate and has a clear physical interpretation.     

Numerical Analysis of Finite Deformation of Overbroken Rock Mass in Gob Area Based on Euler Model of Control Volume

The overbroken rock mass of gob areas is made up of broken and accumulated rock blocks compressed to some extent by the overlying strata. The beating pressure of the gob can directly affect the safety of mining fields, formarion of road retained along the next goaf and seepage of water and methane through the gob. In this paper, the software RFPA＇2000 is used to construct numerical models. Especially the Euler method of control volume is proposed to solve the simulation difficulty arising from plastically finite deformations. The results show that three characteristic regions occurred in the gob area： （1） a naturally accumulated region, 0-10 m away from unbroken surrounding rock walls, where the beating pressure is nearly zero; （2） an overcompacted region, 10-20 m away from unbroken walls, where the beating pressure results in the maximum value of the gob area; （3） a stable compaction region, more than 20 m away from unbroken walls and occupying absolutely most of the gob area, where the beating pressures show basically no differences. Such a characteristic can exolain the easy-seeoaged “O”-ring phenomena around mining fields very well.     

大定源瞬变电磁法在探测煤矿采空区富水性中的研究

大定源瞬变电磁法目前已成为许多矿区水文地质勘查的首选方法.而煤矿老窑采空区出水已成为矿井突水的显著特点之一,因此,本文使用大定源瞬变电磁法对采空区的富水性进行了研究.作者基于电磁场的基本理论研究了大定源瞬变电磁场响应分布规律,并通过一个工程实例证明了瞬变电磁法在探测煤矿采空区富水性方面是有效的.     

Prevention of gob ignitions and explosions in longwall mining using dynamic seals

Most, if not all longwall gob areas accumulate explosive methane-air mixtures that pose a deadly hazard to miners. Numerous mine explosions have originated from explosive gas zones(EGZs) in the longwall gob. Since 2010, researchers at the Colorado School of Mines(CSM) have studied EGZ formation in longwall gobs under two long-term research projects funded by the National Institute for Occupational Safety and Health. Researchers used computational fluid dynamics along with in-mine measurements. For the first time, they demonstrated that EGZs form along the fringe areas between the methane-rich atmospheres and the fresh air ventilated areas along the working face and present an explosion and fire hazard to mine workers. In this study, researchers found that, for progressively sealed gobs, a targeted injection of nitrogen from the headgate and tailgate, along with a back return ventilation arrangement, will create a dynamic seal of nitrogen that effectively separates the methane zone from the face air and eliminates the EGZs to prevent explosions. Using this form of nitrogen injection to create dynamic seals should be a consideration for all longwall operators.     

Discrete modeling of a longwall coal mine gob for CFD simulation

One area of concern in longwall coal mines is the active gob directly behind the longwall face, where high concentrations of methane are likely to accumulate and active roof caving occurs. Using computational fluid dynamics(CFD) to simulate gas flows in and through the gob, most researchers have represented the entire gob as a porous medium governed by Darcy's law. However, Darcy-type porous flow may not be applicable for the highly porous and unconsolidated fringes of the gob. In addition, porous medium models do not allow for representative combustion modeling to simulate in-gob ignition and flame propagation. This study presents a hybrid approach to modeling the gob using CFD: the outer part of the gob is modeled as discrete objects that simulate coarse rock rubble, while the gob center is modeled as a porous medium.     

“三软”厚煤层瓦斯抽放方法研究

告成煤矿的主采二1煤层属典型“三软”厚煤层,回采工作面隅角和回风流中瓦斯体积分数超限的主要原因是采空区瓦斯涌出过多,采取顶板岩石钻孔的方法对采空区冒落带及冒落裂隙带的瓦斯进行抽放,降低了回采工作面隅角和回风流中的瓦斯体积分数,避免了采煤工作面隅角和回风流瓦斯体积分数超限,同时克服了工作面风速超限的问题.实践表明,顶板岩石钻孔抽放冒落带及冒落裂隙带的瓦斯,是解决“三软”厚煤层瓦斯超限的有效途径.     

Synergistic instability of coal pillar and roof system and filling method based on plate model

The security challenges from room and pillar gobs include land subsidence, spontaneous combustion of coal pillars and mine flood caused by gob water. To explore the instability mechanism of room and pillar gob, we established a mechanical model of elastic plate on elastic foundation in which pillars and hard roofs were considered as continuous Winkler foundations and elastic plates, respectively. The synergetic instability of pillar and roof system was analyzed based on plate bending theory and catastrophe theory. In addition, mechanical conditions and math criterion of roof failure and overall instability of coal pillar and roof system were given. Through analyzing both advantages and disadvantages of some technologies such as induced caving, filling, gob sealing and isolation, we presented a new filling method named box-filling, in view of box foundation theory, to control the disasters of ground collapse, water inrush and mine fire. In a gob’s treatment project in Ordos, safety assessment and filling design of a room and pillar gob have been done by the mechanical model. The results show that the gob will collapse when the pillars’ average yield band is wider than 0.93 m, and box-filling can control land collapse, mine flood and mine fire economically and efficiently. So it is worth to study further and popularize.