Stability of slopes in a fire-prone mine in Jharia Coalfield, India

Stability of slope in an opencast mine is always associated with safety and economics. The steeper slope is always preferred from economic point of view but prone to failure, whereas flatter slopes are uneconomical. A proper understanding of slope which will be a steep enough to be stable is required for safety, economy, and stability of men and machineries. The Rajapur opencast mine is one of the important mines in terms of good quality coal but has problems of water seepage, fire, and weak overburden materials. The existing coal mine has three working seams which are mostly thick and occur at shallow depths of about 50–60 m. Overall slope angle of the working faces as well as final pit is very steep which leads to failures. In the present paper, an attempt has been made to characterize the materials of the mine for simulation of existing slopes. The rock samples from the coal measures were collected to determine the petrophysical characteristics of various rock units. All the pertinent geological parameters from the exposed face were also collected during field visit to assess the slope mass rating (SMR). A two-dimensional finite difference tool was employed to simulate the existing slope geometry as well as relevant parameters of the rock units. The numerical simulation indicates various vulnerable points which are prone to failure as well as displacements at various points along the slope. The results of simulations are corroborated with the SMR value. The results are well matching with the field condition.     

Causes, mechanism and environmental impacts of instabilities at Himmetoğlu coal mine and possible remedial measures

 Since the commencement of mining at the Himmetoğlu coal mine, northwest Turkey, serious stability problems have led to interruptions in mining and some environmental effects. A geotechnical investigation was initiated in 1997 and the significant factors that influence the stability have been defined. This paper outlines the results of the field and laboratory studies associated with the causes and mechanism of the slope instabilities and their environmental impacts. The possible remedial measures to improve the stability and to minimize the environmental problems are also described. Back-analyses and data from long-term monitoring indicate that the failures occur along two or three planar surfaces by combination of faults and localized strata steepening adjacent to the faults. The stability is sensitive to changes in length of the lower part of the basal sliding surface and shear strength of the bedding surfaces in the overburden. Suitable remedial measures include slope flattening (i.e. staged bench stripping), proper drainage and spreading of a rock blanket on the pit floor to increase spoil pile stability. Received: 18 April 2000 · Accepted: 15 August 2000     

Fracture flow and groundwater compartmentalization in the Rollins Sandstone, Lower Mesaverde Group, Colorado, USA

 This paper presents a site-specific conceptual model of groundwater flow in fractured damage zones associated with faulting in a package of sedimentary rocks. The model is based on the results of field and laboratory investigations. Groundwater and methane gas inflows from fault-fracture systems in the West Elk coal mine, Colorado, USA, have occurred with increasing severity. Inflows of 6, 160 and 500 L s⁻¹ discharged almost instantaneously from three separate faults encountered in mine workings about 460 m below ground level. The faults are about 600 m apart. The δ ²H and δ ¹⁸O compositions of the fault-related inflow waters and the hydrodynamic responses of each fault inflow indicate that the groundwaters discharge from hydraulically isolated systems. ¹⁴C data indicate that the groundwaters are as much as 10,500 years old. Discharge temperatures are geothermal (≈30°C), which could indicate upwelling from depth. However, calculations of geothermal gradients, analysis of solute compositions of groundwater in potential host reservoirs, geothermometer calculations, and results of packer testing indicate that the fractured groundwater reservoir is the Rollins Sandstone (120 m thick) directly beneath the coal seams. The packer test also demonstrates that the methane gas is contained in the coal seams. A geothermal gradient of 70–80°C km⁻¹, related to an underlying intrusion, is probably responsible for the slightly elevated discharge temperatures. Large discharge volumes, as great as 8.2×10⁵m³ from the 14 South East Headgate fault (14 SEHG), rapid declines in discharge rates, and vertical and horizontal permeability (matrix permeability generally <0.006 Darcy) indicate fracture flow. An in-mine pumping test demonstrates that the 14 SEHG fault has excellent hydraulic communication with fractures 50 m from the fault. Aeromagnetic data indicate that the faults are tectonically related to an igneous body that is several thousand meters below the coal seams. Exploratory drilling has confirmed a fourth fault, and two additional faults are projected, based on the aeromagnetic data. The conceptual model describes a series of parallel, hydraulically separate groundwater systems associated with fault-specific damage zones. The faults are about 600 m apart. Groundwater stored in fractured sandstone is confined above and below by clayey layers. Received March 1999 / Revised, November 1999 / Accepted, December 1999     

Environmental characterisation of coal mine waste rock in the field: an example from New Zealand

Characterisation of mine waste rock with respect to acid generation potential is a necessary part of routine mine operations, so that environmentally benign waste rock stacks can be constructed for permanent storage. Standard static characterisation techniques, such as acid neutralisation capacity (ANC), maximum potential acidity, and associated acid–base accounting, require laboratory tests that can be difficult to obtain rapidly at remote mine sites. We show that a combination of paste pH and a simple portable carbonate dissolution test, both techniques that can be done in the field in a 15 min time-frame, is useful for distinguishing rocks that are potentially acid-forming from those that are acid-neutralising. Use of these techniques could allow characterisation of mine wastes at the metre scale during mine excavation operations. Our application of these techniques to pyrite-bearing (total S = 1–4 wt%) but variably calcareous coal mine overburden shows that there is a strong correlation between the portable carbonate dissolution technique and laboratory-determined ANC measurements (range of 0–10 wt% calcite equivalent). Paste pH measurements on the same rocks are bimodal, with high-sulphur, low-calcite rocks yielding pH near 3 after 10 min, whereas high-ANC rocks yield paste pH of 7–8. In our coal mine example, the field tests were most effective when used in conjunction with stratigraphy. However, the same field tests have potential for routine use in any mine in which distinction of acid-generating rocks from acid-neutralising rocks is required. Calibration of field-based acid–base accounting characteristics of the rocks with laboratory-based static and/or kinetic tests is still necessary.     

The use of air decks in production blasting in an open pit coal mine

The influence of air deck blasting on blast performance and blast economics and its feasibility has been studied in the production blasting of soft and medium strength sandstone overburden rocks in an open pit coal mine in India. The air deck blasting technique was very effective in soft and medium strength rocks. Its main effects resulted in reducing fines, in producing more uniform fragmentation and in improving blast economics. The fines were reduced by 60–70% in homogeneous sandstones. Oversize boulders were reduced by 80% and shovel loading efficiency was improved by 20–40% in blocky sandstones. The explosive cost was reduced by 10–35% dependent on the type of rock mass. Throw, backbreak and ground vibration were reduced by 10–35%, 50–80% and 30–94% respectively. For a particular rock mass and blast design environment, air deck length (ADL) significantly influenced the fragmentation. ADL as represented by air deck factor (ADF) in the range of 0.10–0.35 times the original charge length (OCL) produced optimum results. ADF beyond 0.35 resulted in poor fragmentation and in inadequate burden movement.     

急斜特厚煤层开采地表沉陷特征立体实验研究

借助急斜煤层大型立体模拟试验架,对急斜煤层水平分段放顶煤开采地表变形破坏特征进行了开采的立体模拟试验研究。研究发现,急斜煤层开采后形成的沉陷不同于缓斜煤层,其沉陷最初由在地表生成的孔洞发展为孔洞间的贯通,形成塌陷坑。塌陷坑靠顶板侧岩体的垮落程度明显大于靠底板侧岩体的垮落程度,而且沉陷随着分段工作面的向下延伸表现为反复多次沉陷,塌陷坑内垮落体表现为由底板侧朝顶板侧的台阶式下降分布,最终形成深槽型塌陷坑。     

Stable isotope and fluid inclusion evidence for the origin of the Brandberg West area Sn–W vein deposits, NW Namibia

The Brandberg West region of NW Namibia is dominated by poly-deformed turbidites and carbonate rocks of the Neoproterozoic Damara Supergoup, which have been regionally metamorphosed to greenschist facies and thermally metamorphosed up to mid-amphibolite facies by Neoproterozoic granite plutons. The meta-sedimentary rocks host Damaran-age hydrothermal quartz vein-hosted Sn–W mineralization at Brandberg West and numerous nearby smaller deposits. Fluid inclusion microthermometric studies of the vein quartz suggests that the ore-forming fluids at the Brandberg West mine were CO₂-bearing aqueous fluids represented by the NaCl–CaCl₂–H₂O–CO₂ system with moderate salinity (mean=8.6 wt% NaCl_equivalent).Temperatures determined using oxygen isotope thermometry are 415–521°C (quartz–muscovite), 392–447°C (quartz–cassiterite), and 444–490°C (quartz–hematite). At Brandberg West, the oxygen isotope ratios of quartz veins and siliciclastic host rocks in the mineralized area are lower than those in the rocks and veins of the surrounding areas suggesting that pervasive fluid–rock interaction occurred during mineralization. The O- and H-isotope data of quartz–muscovite veins and fluid inclusions indicate that the ore fluids were dominantly of magmatic origin, implying that mineralization occurred above a shallow granite pluton. Simple mass balance calculations suggest water/rock ratios of 1.88 (closed system) and 1.01 (open system). The CO₂ component of the fluid inclusions had similar δ ¹³C to the carbonate rocks intercalated with the turbidites. It is most likely that mineralization at Brandberg West was caused by a combination of an impermeable marble barrier and interaction of the fluids with the marble. The minor deposits in the area have quartz veins with higher δ ¹⁸O values, which is consistent with these deposits being similar geological environments exposed at higher erosion levels.     

蒙东地区露天矿边坡稳定性影响因子与敏感度分析

边坡稳定性对露天煤矿安全高效开采至关重要。在系统总结蒙东地区露天煤矿赋存条件的基础上,提出了该地区露天煤矿边坡的工程地质特征及稳定性影响关键因子。采用正交试验与极差分析法,对该地区露天煤矿边坡稳定性影响因子的敏感度进行了研究。研究结果表明：软弱结构面分布特征、软弱结构面强度及变形特征、地下水疏排效果和综合帮坡角是控制该地区露天煤矿边坡稳定性的关键因子;不同开采阶段边坡稳定性影响因子的敏感性会发生变化,边坡防治策略及重点也应相应调整。     

Application of Air Decks in Production Blasting to Improve Fragmentation and Economics of an Open Pit Mine

In blasting with air decks, repeated oscillation of shock waves within the air gap increases the time over which it acts on the surrounding rock mass by a factor at between 2 and 5. The ultimate effect lies in increasing the crack network in the surrounding rock and reducing the burden movement. Trials of air deck blasting in the structurally unfavourable footwall side of an open pit manganese mine has resulted in substantial improvements in fragmentation and blast economics. Better fragmentation resulted in improved shovel loading efficiency by 50–60%. Secondary blasting was almost eliminated. Use of ANFO explosive with this technique reduced explosive cost by 31.6%. Other benefits included reductions in overbreak, throw and ground vibration of the order of 60–70, 65–85 and 44% respectively. This paper reviews the theory of air deck blasting and describes in detail the air deck blast trials conducted in a manganese open pit mine in India. The blast performance data have been analysed to evaluate the benefits of air decking over conventional blasting.     

Experimental studies on three potassium-rich ultramafic rocks from Damodar Valley, East India

Summary An experimental study on the phase relationships of three potassium-rich ultramafic rocks from the Damodar Valley, Gondawana basins, has been performed under upper mantle P–T conditions (1.0–2.5 GPa, 700–1200 °C). The Mohanpur lamproite and Satyanarayanpur minette, both from the Raniganj basins, have been investigated with the addition of 15 wt% H₂O. No water was added in the experiments done on an olivine minette from the Jarangdih coal mine, Bokaro Basin, which originally contains 15 wt% CO₂ and 2.86 wt% H₂O. In all cases, olivine is the liquidus phase followed by phlogopite. The subsolidus assemblage for the three rocks is a phlogopite-bearing harzburgite, associated with apatite, Mg-ilmenite and carbonates for the Jarangdih rock; apatite, chromian spinel and carbonates and priderite (only between 1.0 and 1.2 GPa) in the case of the Mohanpur lamproite, and finally apatite, chromian spinel, rutile, and carbonate in the Satyanarayanpur sample. Although orthopyroxene is absent in the natural potassium-rich ultramafic rocks, its presence in the run products of the Jarangdih rock is possibly related to a reaction between olivine and a CO₂-bearing fluid phase. The presence of orthopyroxene in the run products of Mohanpur and Satyanarayanpur rocks may be due to a reaction between K-feldspar, olivine and a vapour phase to produce phlogopite and orthopyroxene. On the basis of present experimental investigation and isotopic studies made by previous investigators, it has been suggested that these K-rich rocks have crystallized from melts derived by vein-plus-wall-rock melting of a phlogopite-bearing harzburgite source rock. Received December 15, 1999; revised version accepted June 17, 2001     

Geotechnical applications in open pit mining

Detailed geotechnical data is often a major unknown factor in open pit design and mining, the lack of which constitutes a significant risk in any mining venture. As geotechnical data is accumulated so the risk of unforeseen conditions reduces, and so safety and productivity can be increased. Previously, most geotechnical work undertaken at open pit mines has focused on the slopes. The work done at Sandsloot open pit situated on the northern limb of the Bushveld Complex, 250 km north east of Johannesburg, however, has involved using geotechnical data for production, as well as slope stability benefits. Solutions to production problems encountered in a rapidly developing open pit are best formulated once some geotechnical control at the pit has been attained. At Sandsloot open pit this was achieved by delineation of geotechnical design zones from a detailed face mapping and drilling programme. Optimum design parameters then were assigned to these zones and geotechnically related problems assessed. This allowed slope management programmes to be initiated, as well as slope optimization of the hangingwall. The latter resulted in an improved slope configuration and an increase in the ultimate angle of the wall by 7°. This resulted in substantial savings, as well as an improvement in safety. In addition, the zones can be used for planning, costing and pit scheduling. The methods have proved successful in optimizing blast fragmentation and thereby loading, crushing and milling rates; in reducing secondary blasting and improving floor conditions; and in reducing drilling, blasting and comminution costs.     

Effect of Underground Mine Blast Vibrations on Overlaying Open Pit Slopes: A Case Study for Daye Iron Mine in China

Investigating the propagation and attenuation of blast vibration in rock slopes is the key point to assess the influence of underground mine blasting on overlaying open pit slopes stability and determining the potential risk. In this paper, Daye Iron Mine in China has been chosen as the case to study the effect of blast vibrations on overlaying open pit slopes due to underground mine blast. Firstly, the characteristics of blast loadings are analyzed by the dynamic finite element method. Then, a three dimensional (3D) numerical model of the open pit and the underground mine is made, which is verified by the field monitoring data to prove its reliability. The effect of blast vibration on overlaying open pit slope due to underground mine blasting are discussed based on the peak particle velocity (PPV) and the peak effective tensile stress (PETS) distribution characteristics which are calculated and analyzed by inputting the obtained blast vibration data into the numerical model. The results show that the effect of present mining blasting on the stability of pit slopes are limited because the simulated maximum PPV and PETS of monitoring point on slopes are all < 0.747 cm/s and 0.738 MPa. At last, according to numerical simulations of the underground mine blasting, the PPV predicting formulas for the slopes in Daye Open Pit Iron Mine is proposed based on the classic Sadaovsk formula.     

Young orogenic gold mineralisation in active collisional mountains, Taiwan

Gold-bearing vein systems in the high mountains of Taiwan are part of the youngest tectonic-hydrothermal system on Earth. Tectonic collision initiated in the Pliocene has stacked Eocene–Miocene marine sedimentary rocks to form steep mountains nearly 4 km high. Thinner portions of the sedimentary pile (∼5 km) are currently producing hydrocarbons in a fold and thrust belt, and orogenic gold occurs in quartz veins in thicker parts of the pile (∼10 km) in the Slate Belt that underlies the mountains. Metamorphic fluids (2–5 wt.% NaCl equivalent) are rising from the active greenschist facies metamorphic zone and transporting gold released during rock recrystallisation. Metamorphic fluid flow at the Pingfengshan historic gold mine was focussed in well-defined (4 km³) fracture zones with networks of quartz veins, whereas large surrounding volumes of rock are largely unveined. Gold and arsenopyrite occur in several superimposed vein generations, with ankeritic alteration of host rocks superimposed on chlorite–calcite alteration zones as fluids cooled and became out of equilibrium with the host rocks. Mineralising fluids had δ¹⁸O near +10‰, δ¹³C was between −1‰ and −6‰ and these fluids were in isotopic equilibrium with host rocks at ∼350°C. Ankeritic veins were emplaced in extensional sites in kink fold axial surfaces, formed as the rock mass was transported laterally from compressional to extensional regimes in the orogen. Rapid exhumation (>2 mm/year) of the Slate Belt is causing a widespread shallow conductive thermal anomaly without igneous intrusions. Meteoric water is penetrating into the conductive thermal anomaly to contribute to crustal fluid flow and generate shallow boiling fluids (∼250°C) with fluid temperature greater than rock temperature. The meteoric-hydrothermal system impinges on, but causes only minor dilution of, the gold mineralisation system at depth.     

构造煤和煤与瓦斯突出关系的研究

深部煤炭开采地质条件恶化,原生煤在多期构造运动作用下形成松软低渗高瓦斯构造煤层,煤层钻孔施工困难,爆破增透产生的裂隙不发育且易于重新压实。针对目前构造煤层顶板爆破致裂增透关键技术没有得到根本突破问题,构建试验模型进行煤层顶板爆破相似模拟试验和数值分析,监测跨界面应力波传播和宏观三维裂隙演化形态,再现了爆破应力波传播和煤岩体内部损伤破坏过程。研究表明：(1) 构造煤层爆破损伤范围主要集中在爆破孔和煤层上下煤岩交界面附近煤体;构造煤顶板爆破产生跨界面致裂卸压裂纹,爆破损伤沿爆破孔向四周岩体扩展,最后蔓延到煤层底板,爆破孔位置和上部煤岩交界面以及煤层内部的损伤较为严重。(2) 爆破应力波从构造煤层顶板传播到煤岩交界面时发生波的透射和反射,透射的压缩应力波破坏煤体;反射的拉伸应力波反作用于煤岩交界面区域岩体。(3) 爆破累积损伤产生的跨界面交叉裂纹卸压,使顶板岩层裂隙和构造煤层裂隙贯通,有利于构造煤层的瓦斯垂向运移流动和卸压瓦斯抽采。现场应用表明,煤层顶板爆破瓦斯抽采纯量及其浓度快速上升,瓦斯抽采纯量从爆破前的0.07 m³/min提高到1.73 m³/min,体积分数从10.46%上升到68.50%,并且长时间维持在较高水平。研究成果可为深部构造煤层瓦斯高效抽采提供理论基础和技术支持。

     

Permo-Carboniferous coal measures in the Qinshui basin: Lithofacies paleogeography and its control on coal accumulation

The Qinshui basin in southeastern Shanxi Province is an important base for coalbed methane exploration and production in China. The methane reservoirs in this basin are the Carboniferous and Permian coals. Their thickness is strongly controlled by the depositional environments and the paleogeography. In this paper, sedimentological research was undertaken on the outcrop and borehole sections of the Taiyuan and Shanxi formations in the Qinshui basin and the basin-wide lithofacies paleogeography maps for these two formations have been reconstructed. The Taiyuan Formation is composed of limestones, aluminous mudstones, siltstones, silty mudstones, sandstones, and mineable coal seams, with a total thickness varying from 44.9 m to 193.48 m. The coal seams have a thickness ranging between 0.10 and 16.89 m, averaging 7.19 m. During the deposition of the Taiyuan Formation, the northern part of the basin was dominated by a lower deltaic depositional system, the central and southern parts were dominated by a lagoon environment, and the southeastern corner was occupied by a carbonate platform setting. Coal is relatively thick in the northern part and the southeastern corner. The Shanxi Formation consists of sandstones, siltstones, mudstones, and coals, with the limestones being locally developed. The thickness of the Shanxi Formation is from 18.6 m to 213.25 m, with the thickness of coal seams from 0.10 to 10 m and averaging 4.2 m. During the deposition of the Shanxi Formation, the northern part of the Qinshui basin was mainly dominated by a lower deltaic plain distributary channel environment, the central and southern parts were mainly an interdistributary bay environment, and the southeastern part was occupied by a delta front mouth bar environment. The thick coals are distributed in the central and southern parts where an interdistributary bay dominates. It is evident that the thick coal zones of the Taiyuan Formation are consistent with the sandstone-rich belts, mainly located in the areas of the northern lower deltaic plain and southeastern barrier bar environments, whereas the thick coal zones of the Shanxi Formation coincide with the mudstone-rich belts, located in the areas of the central and southern interdistributary bay environments. Translated from Journal of Palaeogeography, 2006, 8(1): 43–52 [译自: 古地理学报]     

白音华一号露天南帮工程地质特征分析

在分析矿区地层岩性、构造和水文地质条件的基础上,依据岩石的物理力学性质,确定了矿区边坡的软弱层面,同时对矿区南帮（非工作帮）的工程地质特征进行了研究。认为：第四系松散层具饱水性质,新近系地层以膨胀性的粘土（岩）为主,可塑性较强,易崩解,抗压、抗剪强度低,煤系地层以软岩为主,力学强度亦低,矿区工程地质特征为二类一型。据此预测了该区可能产生的工程地质问题,并提出了相应预防措施。     

煤层流变及其与煤矿瓦斯突出的关系—以淮北海孜煤矿为例

复杂地质条件下煤层受层间滑动作用容易发生流变。本文以淮北海孜煤矿为例，详细分析了煤层流变所引起的煤层形变宏观、微观及构造煤特征，总结了煤层流变构造发育的规律。煤层流变引起煤层形态、煤厚及煤体结构的变化，并形成各种构造煤。利用煤镜质组光率体各向异性进行了应力、有限应变分析，探讨了煤层流变机制是以剪切为主，伴有挤压的后期构造作用。海孜煤矿构造活动具有多期性，但煤层受力的主要方向始终为NW－SE向，这与煤层发生流变形成总体NE－SW向增厚变薄带的展布方向是一致的。已采区的煤层流变有：韧性流变、脆性流变及韧脆性流变。煤层流变引起的厚度变化和煤体结构的破坏是造成煤矿瓦斯突出的主要因素。     

The role of infiltration processes in steep slope stability of pyroclastic granular soils: laboratory and numerical investigation

Rainfall-induced landslides on steep slopes are a common feature in much of Italy’s mountain areas covered by shallow-pyroclastic deposits. Generally, these deposits are unsaturated and have a slope angle higher than 40°–50°; hence their stability is due to the positive effect of matric suction on soil shear strength. During rainfall, rainwater infiltration causes a decrease in suction, which in turn causes changes in soil mechanical and hydraulic properties, leading towards an instability process. However, the response of pyroclastic soil slopes to rainwater infiltration is not fully understood. The aim of this study is to link slope instability to the infiltration process on the basis of advanced geotechnical characterization, in situ monitoring and numerical analysis calibrated through a back-analysis of well-instrumented flume tests.     

Rock—Forming and Ore—Forming Temperatures of Lianhuashan Tungsten Deposit,Guangdong Province

The Lianhuashan tungsten deposit occurs in the volcanic terrain in the coastal area of Southeast China,where rhyolite,quartz porphyry and granite consitute a complee magmatic series.The orebodies are located in the endo-and exo-contacts between the quartz porphyry and the metasandstone of the Xiaoping coal measues.Hongenization temperatures of melt inclusions in zircon and quartz are 1100℃and 1050℃ for rhyolite,1000℃ and 860℃for quartz porphyry,and 950-1000℃and 820℃ for granite,respectively,demonstrating that the rockforming temperatures dropped successively from the eruptive to the intrusive rocks and that the homogenization temperatures of melt inclusions in zircon are 50-180℃higher than those in quartz.Homogenization temperatures of gas-liquid inclusions in quartz are 230-520℃（mostly 230-270℃）for quartz porphyry,200-450℃（mostly 200-360℃）for ore-bearing quartz veins,150-210℃for granite 170-200℃ for the vein quartz in it.Quartz from the quartz porphyry and from the ore-earing quartz veins show similar characteristics in inclusion type and homogenization temperature,indicating that intergranular solutions must have been formed upon cooling of magma and that ore-forming solutions for the tungstem mineralization were evolved mainly from ore-bearing intergranular solutions in the quartz porphyry.     

Electrical Resistivity Imaging technique to delineate coal seam barrier thickness and demarcate water filled voids

Exploration and exploitation of coal seams is one of the major resources for the energy sector in any country but at the same time water filled voids/water logged areas in the old workings of these seams are very critical problems for the coal mining industry. In such situations, disasters like inundation, landslides, collapsing of the old seams may occur. In this regard, it is necessary to find out the water saturated/water filled voids and zones in the mining areas. Since no established technique is available to find such zones, an experimental study using Electrical Resistivity Imaging (ERI) has been carried out in one of the coal mining areas near Dhanbad, to find out the feasibility of finding the barrier thickness and the water logged area in underground coal mines. The area under study forms part of Jharia coalfield in Dhanbad district, Jharkhand state. The coal bearing rocks of Barakar Formation of Lower Permian age (Gondwana period) occur in the area under a thin cover (10 m to15 m) of soil and or alluvium. Coal bearing Barakar Formations consist mainly of sandstone of varying grain size, intercalation of shale and sandstone, grey and carbonaceous-shale and coal seams. Since the water saturation reduces the resistivity of a formation to a large extent, water filled voids and old coal workings are expected to have significant resistivity contrast with the surrounding host rock. Hence, ERI technique was applied in such an environment as this technique uses high-density data acquisition both laterally and vertically by using multiple number of electrodes. Along with ERI, mise-à-la-masse (also called charged body) technique was also employed at one of the promising sites to find out the connectivity of water logged areas and also detection of these old workings from the surface measurements was analyzed. The interpreted 2D resistivity sections have clearly indicated the water bearing zone(s) along the profile which was well confirmed with the existing water level in the nearby borewells. On the other hand, this technique did not identify the size of the coal pillar and gallery (air filled voids), which might be due to the small size of the voids (i.e. about 2 m × 2 m) below a depth of 15m and more but have indicated altogether as a high resistive zone ranging from 600–1000 Ohm-m.