外文翻译-机械化矿井导水裂隙带高度的检测

英译汉Height and detection of water flowing fractured zone in fully mechanized mining areaBaishan Xu1, Qi Li1, Zhihong Li2, Zhijian Haol, Guojun Gao3 1.School of Resource and Civil Engineering, Northeastern University, Shenyang, Liaoning 110004,China2.Institute of Geophysical Prospecting, Nanjing 130026, China3.Tiefa Coal lndustry(Group)Limited Liability Company Shenyang 110500, Chin AbstractAbstract: Coal mining like mining underneath buildings, roads, or waters changes the distribution of stress in rock mass, resulting in deformations between the roof and the surface, as well as crisscrossing fractures in the mining rock mass. These fractures and deformations affect the mechanic behaviors of the rock mass, and to some extent control its stability. As mining continues, stress balance will be lost, which may lead to collapsing of the rock mass around stope. Therefore, the monitoring of water flowing fracture zone of overlying strata is a vital problem. This paper studies the relationship between the water flowing fracture zone and mining by taking the fully mechanized mining underneath waters as an example. It concludes that the variations and distribution of fractures in the mining rock mass can be revealed by P- and S-wave seismic survey, which ensures miming of coal seam safely. S-wave reflection survey can be used to detect the formations with water flowing fractures and characterize the development degree of the fractures. The validity of the proposed method was verified by drilling. The proposed method provides support for mining of coal seam of over 10m at onetime under water reservoir.Key words: SV wave Exploration, mined-out areas,coal seam, water flowing fracture zone, geophysical methodsIntroductionFor coal mining under buildings, roads, and waters, the carving zone formed from mining leads to the relocation of stress. The deformations and fractures from stope roof to the earth surface result in a complicated fracture network internal the rock mass. This impacts the mechanic behaviors of the rock mass, or even controls the stability of the cover rock to some extent (Wu et al., 1994). Therefore, the knowledge about the distribution of fractures in the cover rock above coal mine is very important for studying the collapse of the mining rock mass, determining the mechanic parameters for stability prediction of building foundation over mine goaf, and assessing the strength and stability of restructured mining rock mass.Fractures grow upwards from the bottom as the work face advances. These fractures form different network corresponding to different work face. The foregoing network expands, closes or opens along with the work face advancing, which complicates the fracture distribution of mining rock mass. On completion of mining and the rock displacement tends to stabilize, bed separation will basically close in the middle of the goaf. The height of the water flowing fractured zone under certain mining method and scale is the vital information as to determine whether coal mining under waters will give rise to seepage around the reservoir. Traditionally, this height is determined from the washing fluid used during borehole survey and numerical simulation. These methods are ones that infer the global from the local and may fail to reflect the real situation. For the coal seam and overburden bed with weak rock strata and heterogeneous hard rock strata, the overburden bed tends to deform seriously or non-uniformly. In such case, numerical simulation usually fail to yield desired results, and borehole survey also cannot keep track of the progressive destruction and instability, as well as the opening and closing of faults and joints. Seismic exploration with P- and S-waves is able to reflect the changes of fracture network in the mining rock mass. Thus it can beused to safeguard coal mining.1 Characteristics of the overburden bed deformation over the mining areaRocks around the mining goaf undergo complicated displacement and deformation after coal excavation. On its completion the overburden bed can be roughly divided into three zones: carving zone, fractured zone, and bending deformation zone (Yan, 1995). Carving zone is the area where the overburden bed is completely collapsed. The rocks in the carving zone are characterized by irregularity, expansion on breaking, and poor compactness, which hampers roof regeneration and water barrier formation with the carving ground (China Coal Research Institute Beijing Mining Research Institute, 1981). Above the carving zone is the fractured zone. Fractured zone is the area where rocks still keep their original layering structure though they are fractured, separated, and faulted. The distribution of the fractures in the fractured zone possesses a certain zonation. The carving zone and fractured zone are referred as water flowing fractured zone. This zone plays an important role in analyzing the feasibility of coal mining under waters. Only if the height of the overburden bed is no less than that of the water flowing fractured zone, one may sure that the waters will not leak into the mining area. Bending deformation zone is also called bulk moving zone, it is referred to the whole rock body between the top of the fractured zone and the earth surface. The integrity of the rock mass in the bending deformation zone is the last shelter for safeguarding coal mining under waters.2 Geophysical principles and methodsP- and S-wave seismic reflection method is to determine the occurrence of subsurface strata and the characters of structures via the energy reflected from different subsurface interfaces and the travel times of reflections receiving at the earth surface. It provides a direct and highly resolvable geophysical prospecting method for determining the destruction of the overburden bed above mining goaf and the subsequent changes.2-component common offset P- and S-wave seismic reflection method is a new artificial earthquake method. It takes both advantages of P-waves and S-waves. S-waves are superior in resolving interfaces of large dip, whereas P-waves are sensitive to nearly horizontal coal seams and major faults. By combining P-wave data with S-wave data, one is able to detect minor geologic anomalies ant their occurrences. S-wave seismic reflection method is mainly used to resolve complex shallow geological problems. The spacing between observation stations is generally less than lm in S-wave seismic method, much denser than that of borehole survey. It is an efficient while relatively inexpensive method. It has been proved by drilling or digging verification that S-wave seismic is an effective method for solving complex geological problems.3 Case studyA comprehensive study of drilling, geophysical methods, and numerical simulation was carried out to determine the height of water flowing fractured zone and to solve the problems related with borehole survey. Geophysical methods such as EH-4 and P-and-S-wave seismic were used in the experiments of flooding in goaf to characterize the development of the “three zones” and to determine heights of the three zones. These two methods are complementary. They solved the geological problems from viewpoint of electromagnetic field and elastic field, respectively. Seismic method is superior in characterizing rock mass integrally and structurally. In this study, using only hammer as seismic resource can provide seismic images over a depth of near 500m. S-wave seismic together with EH-4 is an ideal combination for study of the inbreak of overburden bed after coal excavation.3 Geological conditions and geophysical characteristics in the coal mining areaThe coal-bearing strata are generally 80800m thick in the mine field. It comprises layers or segments of conglomerate, sandstone, coal, oil shale, zoolite, and mudstone from bottom to top.Fossils are enriched in the segments of coal and oil shale as well as layers of zoolite. The main coal seams are stable in the mine field. Coal seam is a complex of 1-18 natural bed(s), distributing all over the mining field. Its structure is simple with a roof of oil shale and siltstone and thickness of 0.5814.04m.a) Shallow seismic and geologic conditionsWater table is stable with thickness of l5m. Below arable layer is mostly gravel, clay or sandy clay with thickness of generally 15m. This layer is just overlying the Cretaceous stratum. These conditions are favorable for the excitation seismic waves, but will somehow absorbs the seismic waves of high frequency.b) Deep seismic and geologic conditionsThere is noticeable difference of wave impedances between different strata. Strata are of moderate dip. Below the Cretaceous stratum is a thick stratum of glutenite. Significant geophysical differences assure to generate trackably continuous reflection events on seismic sections. The top of the coal seam is oil shale, and its bottom is mainly siltstone and fine sandstone. Considering the large difference of wave impedance between the coal seam and host rock, deep seismic and geologic conditions are favorable for seismic survey.4 Data acquisition and processingOne of the keys to the success of seismic exploration is to acquire high resolution and high signal-to-noise ratio seismic waves. The key to acquire high resolution and high SNR seismic waves is to determine optimal shooting and receiving parameters and layout.2-component common offset seismic reflection method was used. The engineering seismograph used has a dynamic range of more than 126dB and receiving frequency range of 0.15000HZ he low frequency geophone used has a harmonic distortion of less than 0.05% and receiving band of 102000HZammer was used as seismic resource. In land, both weight of 20 pound and machine hammer of 3 tons thrust force were used.Following objectives were set for seismic data processing according to the requirements of geologic task and quality of raw data.a)Preservethe fidelity of seismic data to assure correct imaging of minor faults, fissures, bending deformation zone, fractured zone, carving zone, and minor structures.b)Preservethe amplitude of seismic signals and the kinetics that reflecting the interface characters to facilitate horizon tracing and study of lithological variations.c)InvertP- and S-wave velocity from well data, and perform time-depth conversion with correctly imaged data.To achieve the above objectives, following measures were adopteda)Suppressnoises without doing harm to desired signals to improve SNR.b)Performtrace equalization to assure that the resolution of raw data will not be decreased by data processing.c)Performfiltering on a band division basis to improve resolution and SNR.d)Properlyperform anisotropic correction and phase correction5 Result and interpretationTo show the variations of overburden bed and fractures before and after coal excavation, we will compare the geologic sections resulted from multiple vintages. Here we will demonstrate the exploration achievements with Line A.Table 1. Variations of overburden bed with time as shown on Line AdateFebruary 8March 18May 1Time of aequisition(day)-15377Distance to cutting face(m)58-15830-120-60-120Number of fractures31318 5 - 2 0 0 6 .5-1 100 200 Figl. Seismic section of Line A and interpreted fractures and occurrences of the three zones before, during, and after excavation.5-2006.5-1Fig 2. S-wave seismic section of Line B and its geologic interpretation Line B parallels to themining work face.It was acquired after 180 days of excavation. The maximum height of bending deformation zone is about 290m away from that of the coal seam. The maximum height of the underlying carving zone is about 80m. Fractures increased to 62, and bed separation was well developed.6 Analysis of regularity for the water flowing fractured zoneTo further study the relations between fracture systems and lithology, we did statistics for 32 seismic sections from 8 lines and drew the following chart.The number of fracture varies with lines and time. This indicates that the Jurassic coal-bearing formation has a relatively uniform lithology, whereas the Cretaceous overburden bed changes rapidly in lithology in different directions. It can be seen from the geologic sections that fractures are in oblique line or curves of different dips. This demonstrates their difference in rigidity and plasticity. Therefore the underlying carving zone is stable, whereas the upper bending deformation zone and fractured zone are developed non-uniformly.7 Integrated analysisDominate the Overburden bed falls rapidly in a short period of time after coal excavation. Its maximum height may reach to about 20m. The height of cavingzone may reach up to 80m in along period of time after excavation. At the same time buildup can be seen at the bottom of coal seam. Its maximum height is about 3m. Fractures grow between the top of the coal seam and bottom of the Cretaceous. They carving zone. Fractured zone mainly develops at the bottom of the Cretaceous. This may attribute to the inter-formational sliding caused from stress change alleviating the destruction of the overburden bed.Fig 3. Trend of fracture development after excavationThe extension fractures are caused by uneven subsidence after coal excavation. They usually are of water flowing ability. We should treat the height of water flowing fractured zone equally with the new fractures caused by collapses after excavation unless there is thick plastic water barrier in the Quaternary and it is only bent rather than destroyed.The growth of newly generated fracture is mainly controlled by the displacement of rock in the neighboring goaf. Upon the completion of mining in the current mining field, fractures grow further with the time and the number of newly generated fracture will reach to apex about 3 days after the finishing of mining. Though there are limited observations available, it still be seen that fractures are not straight lines or oblique lines, rather they are a curves crossing lines on S-wave seismic time section. This is because the Cretaceous formation is inhomogeneous.8.ConclusionsSatisfactory results have been achieved for description of the carving zone and water flowing fractured zone caused by goaf in the overburden bed with 2 component common offset seismic method and EH-4 electromagnetic method. We discussed the developing regularity of the water flowing fractured zone in the overburden bed above goaf. The results have been verified by borehole survey in 3 wells and observations taken in and outside mine. Evaluation for the development of the three zones was carried out on the whole survey area. 2 component common offset seismic method takes the advantages of S-wave seismic method and P-wave seismic method. It provides direct information about the geology, hydrology, displacement of overburden bed, structures, and fractures, thus safeguards the fully mechanized mining.References1. China Coal Research Institute Beijing Mining Research Institute. 1981,Theory of Mine Field Surface Movement and Overburden Bed Destruction and itsApplication. Beijing: China Coal Industry Publishing House.2. Specifications of Buildings, Waters, Railway, and Main Mine and Roadway Coal Pillar Design and Coal Mining, Beijing: China Coal Industry Publishing House, 2000.Wu Lixin, Wang Jinzhuang. 1994,heory and Practice of Strip Mining under Buildings or Structures. Xuzhou: China University of Mining and Technology Press.3. Yan Ronggui. 1995.Mining Subsidence and Surface Structure. Beijing: Metallurgical Industry Press.机械化矿井导水裂隙带高度的检测徐白山1,李奇1,李洪志2,郝志坚2,高国军3（1辽宁沈阳东北大学资源与土木工程学院2. 南京理工学院地球物理勘探3.沈阳tiefa责任有限公司）摘要： 位于建筑物，铁路和水体下的三下开采改变了应力在岩体中的分布特征，导上层和地表的变型和岩体的交错裂缝。这些裂缝和变形影响岩体的力学特性，,并在一定程度上影响其稳定性。随着开采的继续，矿山压力可能就会失去平衡，导致围岩的破坏。所以，倒水裂隙带的监测就是一个重要问题。本文以水下开采为例，研究了机械化开采与导水裂隙的关系。本文认为裂隙在矿山岩体中的变化和分布可以由地震的横波和纵波揭示，来确保矿井的安全。横波可以用来探测导水裂隙带的发育特点和程度。这种方法已经有效的被钻测验证，该方法可为超过10米的水库下煤矿开采提供支持。关键词：SV波探测，采空区，煤层，倒水裂隙带引 言建筑物，道路和水体下的三下开采导致岩体应力的变迁。采场顶板的变形在内部形成网状的破坏空间。这影响了岩体的固有特性在一定程度上甚至控制了覆岩的稳定性。因此，了解矿井上部覆岩裂隙的分布对于研究矿山岩体，确定机械参数对采空区稳定性的影响，评估矿山压力的力度和稳定至关重要。裂隙随着工作面的推进由底部向上发展，不同的工作面形成不同的裂隙。随着工作面的推进，形成的网状空间扩张，关闭和打开，使矿山岩体裂隙分布更加复杂。在开采完成，采动围岩趋于稳定后，在采空区的中间会形成分层。在确定的采煤方法下的导水裂隙带高度对于确定岩体的储水是否会引起煤层渗透至关重要。传统上，导水裂隙带的测量是通过钻孔冲洗液观测法和数值模拟。这些方法只是从岩体内部推测的一种方法，可能不能反映出真实的情况。煤层和覆盖层较差的岩层和异构硬岩层,覆盖层往往变形严重或非均匀。在这样情况下，数值模拟通常不能得到准确的结果，井下测量也不能对破坏和不稳定性以及随断层的分裂和闭合做跟踪检测。地震检测所用的纵波和横波则能能反映岩体裂隙网络的变化。因此，该方法可以用来保护矿井。1 矿区表土床变形的特点在煤炭开采的矿山采空区潜移默化的发生位移和变形，煤层采出后，上覆岩层