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1.
Summary The theoretical model of the relationship between sub-surface and surface subsidence movements proposed earlier by the authors of this paper is briefly described and further tested against another case history example. Using this model, the magnitudes of the maximum subsidence, tilt and horizontal strain at sub-surface horizons between the ground surface and seam level are predicted in terms of the magnitudes of the corresponding components at the surface due to the extraction of subcritical panels with a wide range of width-depth ratios and the results presented in the form of nomographs and tables. These graphs and tables could be used to estimate the maximum subsidence, tilt and horizontal strain at any chosen sub-surface horizon associated with the extraction of a subcritical panel from the known corresponding maximum values at the surface.The proposed theoretical model can also be used to predict sub-surface subsidence components at any point within the zone influenced by the extraction of a panel from the corresponding surface subsidence components which may be obtained from field measurements or pre-calculated using any existing method of surface subsidence prediction. As an example, the profiles of surface and sub-surface subsidence at various horizons between the ground surface and the seam level resulting from the extraction of an assumed sub-critical longwall panel are predicted using the theoretical model together with the empirical method of surface subsidence prediction. The pattern of sub-surface subsidence movements in the strata overlying the panel is examined. 相似文献
2.
Grout injection into bed separation to control surface subsidence during longwall mining under villages: case study of Liudian coal mine,China 总被引：2，自引：0，他引：2
Surface subsidence can cause many environmental problems and hazards (including loss of land area and damage to buildings), and such hazards are particularly serious in coal mining districts. Injecting grout into the bed separation in the overburden has been proposed as an effective control measure against surface subsidence during longwall mining. However, no field trials of this technique have been implemented in mines under villages in China, and thus, its ability to control subsidence in such areas has yet to be demonstrated. In this study, field trials using this technique were carried out during longwall mining under villages in the Liudian coal mine, China. The maximum surface subsidence observed after the extraction was only 0.298 m, which accounts for 10 % of the mining height and is 79 % less than the predicted subsidence. Moreover, no damage occurred to the village buildings either during or after extraction and these buildings remain stable. Thus, this study represents the first successful attempt to control surface subsidence under villages in China using grout injection during longwall mining. 相似文献
3.
A GIS-based Weights-of-Evidence model for mapping cliff instabilities associated with mine subsidence 总被引：4，自引：0，他引：4
H. Zahiri D. R. Palamara P. Flentje G. M. Brassington E. Baafi 《Environmental Geology》2006,51(3):377-386
The Weights-of-Evidence (W-of-E) technique was applied, within a geographic information system (GIS), to derive a model of rockfall potential associated with mining-induced subsidence. The purpose of the model was to describe the potential for rockfalls from up to 60 m high steep sandstone gorges and slopes associated with proposed underground longwall operations within the immediate vicinity of a previously mined area. Ten known rock falls associated with the previous mining operation were used as training points. Six evidential themes were considered-slope, cliff height, planform curvature, profile curvature, the distance of the cliff areas from the longwall panels, and the distance of the cliff areas from the river. Two models were created, one based on a mine layout in which longwall panels extend beneath the steep areas of a nearby river, and a second in which the mine layout is modified so that mining does not occur directly beneath or within 50 m of the steep slopes. This is to allow for the comparison of rockfall potential based on different mining configurations. The results demonstrate that the W-of-E method is a suitable tool for mine subsidence impact assessment, and suggest that not mining directly under the Nepean river may decrease rockfall potential, on average, by approximately ten times. Numerous limitations with the results, relating to the availability of appropriate evidential theme data and the accuracy of training points, are discussed. 相似文献
4.
Dynamic Subsidence Characteristics in Jharia Coalfield,India 总被引：1，自引：0，他引：1
Amar Prakash Ajay Kumar Kalendra Bahadur Singh 《Geotechnical and Geological Engineering》2014,32(3):627-635
Surface ground movements are usually described by a number of characteristic indices such as vertical displacement, horizontal strain and slope, which are an inevitable consequence of underground mining. Every point at the surface over a panel is subjected to strain and slope during mining and its investigation is essential to assess the safety of surface structures. Therefore, the behaviour of dynamic active and residual subsidence was studied for a few panels of Jharia coalfield. The subsidence and slope were linearly related to time. Compressive and tensile strains showed typical fluctuating characteristic behaviour. The rate of mining being a key and controlling parameter for rate of subsidence their inter-relationship was developed, which showed a rational trend. Compressive and tensile strains and slope showed poor correlation with rate of face advance. 相似文献
5.
Some villages and bridges are located on the ground surface of the working district no. 7 in the Wanglou Coal Mine. If longwall mining is adopted, the maximum deformation of the ground surface will exceed the safety value. Strip mining is employed for the working district no. 7 which is widely used to reduce surface subsidence and the consequent damage of buildings on the ground surface. To ensure the safety of coal pillars and improve the recovery coefficient, theoretical analysis and numerical simulation (FLAC 3D) were adopted to determine the coal pillar and mining widths and to discuss the coal pillar stress distribution and surface subsidence for different mining scenarios. The results revealed that the width of coal pillars should be larger than 162 m, and the optimized mining width varies from 150 to 260 m. As the coal seam is exploited, vertical stress is mainly applied on the coal pillar, inducing stress changes on its ribs. The coefficient of mining-induced stress varies from 2.02 to 2.62 for different mining scenarios. The maximum surface subsidence and horizontal movement increase as the mining width increases. However, when the mining width increases to a certain value, increasing the pillar width cannot significantly decrease the maximum subsidence. To ensure the surface subsidence less than 500 mm, the mining width should not be larger than 200 m. Considering the recovery coefficient and safety of the coal pillar, a pillar width of 165 m is suggested. 相似文献
6.
Underground coal mining activities in Kozlu Hard Coal Basin have reached a level affecting ground layers inside the mining seams and the surface just above the mining operations, causing movements in vicinity of the basin. The movements emerge as collapsing in vertical direction and as sliding, curling and bending in horizontal direction and are termed mining subsidence since they exhibit themselves in ground layers and on earth surfaces in mining environments. These mining-induced movements cause damages and destructions on structures inside and on the surface of mining grounds, and the dimensions of these damages depend upon quality of structures and magnitude of movements. In order to contribute toward a solution to these problems and to mitigate the effects arising during and after mining activities, one should identify and investigate damage prone movements and determine the movement–time relationship. Therefore, it is immensely important to observe, investigate, and measure these movements in regions where mining activities take place. This study focuses on the surface movement-related deformations on the engineering structures in the basin such as Kozlu Seaport and some part of the Zonguldak-Kozlu Road. For this reason, subsidence monitoring points were established on the engineering structures in the basin in a geodetic network concept, and three periods of precise leveling and static GPS observations were conducted. Analyzing these two types of geodetic observations, active and residual subsidence effects were determined for both Kozlu Seaport and the Road nearby. 相似文献
7.
Jeffery A. Thompson David W. Lamb Paul S. Frazier Bernard Ellem 《Environmental Earth Sciences》2011,62(5):973-984
This paper reports on the design and implementation of a program to monitor the surface effects of longwall mining-induced
subsidence on wine grape yields within vineyards of Australia’s Hunter Valley. Implemented in 2003, this five-year project
incorporated a multi-scale, multi-temporal, sliding window monitoring design synchronised with progression of longwall panels.
On the vineyard-block scale, individual vine panels were sampled for grape yield. On the regional scale measures of vine photosynthetically
active biomass were obtained from remotely sensed, Quickbird satellite imagery. All data were analysed in conjunction with
three identified subsidence “zones”: minimum subsidence associated with chain-pillars, maximum subsidence associated with
the longwall, and a zone corresponding to the transition between them. Visual observations conducted throughout the campaign
confirmed the occurrence of isolated localised surface cracking, particularly in areas of maximum soil tension. However, both
vineyard and block-scale data indicated no obvious, systematic mining-induced viticultural effects in the study site investigated
during the study period. Rather, observed trends in vine yields were better explained by vine biophysical responses to climatic
factors. 相似文献
8.
A Comprehensive Study on Subsidence Control Using COSFLOW 总被引：1，自引：0，他引：1
Increasingly, mine subsidence is becoming a major issue of community concern. Among the measures of subsidence control, a
more effective and economical technology, namely Overburden Grout Injection Technology (OGIT), is recently developed in China
and Australia by injecting waste material into the bed separations during longwall mining to achieve subsidence control. The
OGIT is proposed for the subsidence control in West Cliff Colliery located at the Southern Coalfield of the Sydney Basin,
Australia. The three-dimensional finite element code COSFLOW is applied to investigate in a detail the bed separation developing
with longwall mining and the effect of grout injecting into the separations in order to guide the subsidence control design
when using the OGIT in West Cliff Colliery longwall mining practice. 相似文献
9.
Most coal mines in China use the longwall mining system. High stresses are frequently encountered around development entries at deep mines. This paper presents an alternate longwall mining layout for thick coal seams to minimize ground control problems. In a conventional longwall panel layout, development entries on both ends of the panel are located along the floor, and a coal pillar (chain pillar) is left between adjacent panels to ensure stability. Gateroads on either end of a longwall panel using the layout proposed in this paper are located at different vertical levels within a thick coal seam or in a geologically split coal seam for improved stability. The headgate entry/ies are driven along the floor while the tailgate entry/ies are driven along the roof. Therefore, a longwall face has a gradually elevated or curved section on one end of the panel. For the adjacent panel, the development entry may be located directly below the development entry of the previous panel or may be offset horizontally with respect to it. Based on physical and numerical modeling approaches, it is demonstrated that the stress environment for development entries employing the longwall layout is significantly improved; ground control problems are therefore minimized. 相似文献
10.
长壁孤岛工作面冲击失稳能量场演化规律 总被引：1，自引：0，他引：1
煤矿冲击地压一直是困扰中国煤矿安全的主要问题,而煤矿开采过程中跳采形成的孤岛工作面由于容易产生应力集中,来压强度提高,极容易发生冲击地压。基于唐山矿T2193下孤岛工作面的地质条件,从数值分析的角度研究了煤岩体材料的非均匀性,揭示了孤岛工作面顶板周期来压时煤岩体能量释放的动态特征,分析了工作面前方能量释放激增机制。数值模拟结果显示,长壁工作面回采过程中直接顶的不断垮落造成了老顶悬空距离的不断增大,工作面周期来压时,积聚于老顶岩层内的弹性应变能将瞬间释放,容易引发工作面及巷道的冲击失稳。孤岛工作面由于其特有的矿压显现特征,老顶周期破断时所释放的弹性应变能将更加剧烈,冲击地压势必愈加强烈。孤岛工作面顶底板和煤层的能量释放激增可以作为判断煤岩体冲击失稳的前兆信息。孤岛工作面前方发生冲击破坏的主要原因是由于工作面回采过程中围岩所积聚的大量弹性能在顶板断裂时所伴随的巨大能量释放而造成的。 相似文献
11.
Subsidence development with time — experiences from longwall operations in the Appalachian coalfield
Summary The development of mining subsidence, from the immediate roof to the surface, has a dynamic character and it is related to the progress of underground mining and time. Subsidence prediction methods which can pre-calculate the final and intermediate stages of this process are important in mine design. In this paper a prediction method proposed by Knothe (1953), and based on Gauss distribution of influences and Mitsherlich's law of limited increase, is presented and applied to determine the subsidence development over time in the Appalachian coalfield. The method has yielded very promising results and it was verified for a number of longwall case studies. 相似文献
12.
Assessment of rigid overlying strata failure in face mining 总被引：2，自引：0，他引：2
Eva Jiránková 《Central European Journal of Geosciences》2010,2(4):524-530
The method of overlying strata failure assessment of extracted seams is based upon the simultaneous assessment of surface subsidence and seismic activity, considering the spatiatemporal progress of mining, depending on the character of the rock mass. The rigid overlying strata failure assessment results in finding whether a failure of the firm overlying rocks occurred or whether a strutting arch was formed over the mined-out area. The practical importance of the overlying strata failure assessment consists in determining the size of the mined-out area at which the com-plete failure of the rigid overlying strata occurred and in the assessment of the current stress condition of the overlying strata failure. The assessment method is applicable in deep mine workings where thick coal seams are being mined by means of the method of longwall mining with controlled caving. The results of this method are used to amend contemporary known methods of rock-burst protection, namely (regarding the use of surface measurements for the evaluation) in overlying strata areas. 相似文献
13.
Numerical modelling of multistage caving processes: insights from multi‐seam longwall mining‐induced subsidence 
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下载免费PDF全文 Evaluating the induced subsidence is a critical step in multi‐seam longwall mining. Numerical modelling can be a cost‐effective approach to this problem. Numerical evaluation of longwall mining‐induced subsidence is much more complicated when more than one seam is to be extracted. Only a few research works have dealt with this problem. This paper discusses the essential requirements of a robust numerical modelling approach to simulation of multi‐seam longwall mining‐induced subsidence. In light of these requirements, the previous works on this topic are critically reviewed. A simple yet robust FEM‐based modelling approach is also proposed that is capable of simulating caving process, rock mass deterioration and subsidence around multi‐seam excavations. The effectiveness of this approach in comparison with two other conventional FEM approaches is demonstrated through numerical examples of two different multi‐seam mining configurations. Results show that the proposed numerical modelling approach is the only robust method, which is capable of simulating multi‐seam subsidence in both demonstrated cases. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
14.
Solid backfill mining for coal pillar recovery in industrial squares has to ensure that the mine infrastructure, such as the shafts and substations, is not degraded or has its utility impaired by that mining. At the same time, it is important to recover as much coal as possible. As a result, it is necessary to predict mining subsidence during solid backfilling mining of coal pillars in industrial squares and to optimize the design of the working faces. At the Baishan coal mine in Anhiu province, China, there are thick layers of unconsolidated overburden above the coal seam so it is not appropriate to use the surface subsidence prediction method of equivalent mining height to predict subsidence during the mining of the coal pillars there. In order to find a reasonable coal pillar recovery scheme for the Baishan mine, a numerical simulation method is used to determine the relationships between the compression ratio of the backfilling material and the surface subsidence prediction parameters. Research was done to determine the appropriate parameters, and based on the final prediction parameters and taking the mandated protection standards for buildings and structures into account, surface subsidence is predicted and a backfill mining scheme for pillar recovery is proposed. The results show that of the six mining schemes considered, scheme 5 is the best scheme for coal pillar recovery in the industrial square at the Baishan mine. The research results are significant for similar mines with thick unconsolidated overburden anywhere in the world. 相似文献
15.
The classical influence function method is widely used in mining subsidence prediction, but its use is typically limited to predicting the subsidence associated with horizontal stratiform underground mining when the ground surface is flat. By investigating the topography influence on subsidence under simplified mining conditions, this study attempts to improve the original influence function method to take topographic variations into account. New asymmetrical influence functions are used to simulate element subsidence. Integrating this asymmetrical approach into the influence function method increases the realism of subsidence computation when compared to the numerical simulation results. The maximum subsidence value and influence angle got from field data are introduced into the improved method, then two field subsidence cases are studied and acceptable comparison results are achieved. This improved method should serve as the foundation for future work. 相似文献
16.
通过对比采煤前和采煤塌陷过程中及稳定后包气带结构的变化,详细研究了神府—东胜矿区采煤塌陷对包气带结构的影响。研究结果表明:在采煤塌陷前,包气带组成岩性主要为风积砂岩和萨拉乌苏组粗砂岩,相对较薄,包气带组成介质层序较清晰,各岩性介质颗粒排列有序、均一,包气带内部结构以孔隙为主;在采煤发生后的塌陷非稳定阶段,塌陷裂隙贯通含水层,使地下水大量渗漏,同时产生大量贯穿地表的裂隙,引起岩土孔隙性发生变化,使得塌陷区包气带变厚,在一定深度上结构不均,浅部包气带结构转化为以裂隙为主;到塌陷稳定阶段,包气带结构变化趋于稳定,厚度增加,但在地表以下仍存在一些断续的裂缝(隙),使塌陷区包气带形成以孔隙为主,间夹断续裂隙的特殊包气带结构。 相似文献
17.
Summary A two dimensional finite element model is used to simulate the extraction of coal by the longwall method underneath idealized surface slopes. The resulting subsidence, tilt and horizontal displacement values are compared with similar extractions using the same method beneath initially horizontal surfaces. The conclusions of a parametric study using this model, supported by field evidence, indicate that in areas of rugged topography, simple application of the procedures outlined in the National Coal BoardSubsidence Engineer's Handbook (1975) does not give acceptable predictions of the induced ground movements. 相似文献
18.
19.
Manoj Khanal Deepak Adhikary Chandana Jayasundara Rao Balusu 《Geotechnical and Geological Engineering》2016,34(1):217-235
This paper investigates various multiseam mining related parameters using mine site specific data and numerical simulations. Two important mining effects—subsidence and stress—are analysed for different possible mining layouts. A geological mine dataset has been used to generate a numerical model. The predicted surface subsidence magnitude and surface profile have been compared under different scenarios to assess potential options in multiseam mining strategies. The effects that seam separation distances, mining offset, panel layout and panel orientation each have on surface subsidence and chain pillar stress magnitude have been investigated. The numerical simulation shows that ascending or descending mining directions have little impact on controlling the surface subsidence in multiseam mining and predicted an almost identical maximum stress development at the chain pillars. Numerical simulations infer that the orientation of the top panels control the subsidence profile. 相似文献
20.
煤炭开采引起覆岩破断及地表下沉,覆岩及地表运移规律可反映裂隙带高度的动态演化过程。因地表下沉滞后于煤炭开采,对于废弃采空区,长期压实作用导致裂隙带高度较采动期间有所降低。基于地表点下沉速度的阶段特征将裂隙带高度的演化过程分为2个阶段,第1阶段裂隙带发育对应岩层破断逐步向上传递的过程,第2阶段裂隙带高度降低对应离层及裂隙闭合、断裂岩层受压后变形回弹及破碎岩体自然压实的过程。着眼于压实作用对裂隙带高度的影响,根据煤层采厚、垮落带和裂隙带岩层变形量及地表下沉值之间的定量关系,建立了第2阶段裂隙带高度预测模型,并结合太平煤矿实测结果进行验证,采用控制变量法分析了单一因素影响下废弃采空区裂隙带高度的演化特征。结果表明：废弃采空区裂隙带高度受控于垮落带块体强度、垮落带初始碎胀系数、采动期间裂隙带高度最大值及对应的垮落带高度、煤层埋深、地表最终下沉量等因素,太平煤矿采后15 a的裂隙带高度实测值11.36～13.00 m与理论预测值12.75 m吻合度较高,模型的可靠性得到验证。最后,应用此预测模型对武安煤矿（关停矿井）2002－2003年采空区裂隙带高度开展理论计算,结合地空瞬变电磁探测确定了地面瓦斯抽采钻孔理想的终孔位置并成功开展了地面钻孔瓦斯抽采试验。 相似文献