A study on the development of subsidence due to the extraction of 1203 slice with its associated factors around Barapukuria underground coal mining industrial area,Dinajpur, Bangladesh

Subsidence as a result of an underground coal mine is a hazard to human life, properties and environment. This incidence usually occurs over a long period of time which directly or indirectly pertinent with various factors that needs to be carefully considered and systematically analyzed when exploring land subsidence. In reality the relationships among factors, their effects and the subsidence are crucial to have the suitable management plan for the mine-induced ground subsidence around the mining area. In this research, primarily the development of subsidence caused by the extraction of 1203 slice has been evaluated under the profile functions and influence functions methods. The results show that the calculated subsidence profile is almost trough-like subsidence where the maximum amount of subsidence is about 0.89 m. Secondly, based on this result, the analysis on different factors such as the deeper coal bed (420 m depth level) and higher angle of draw (42.5^o) show less subsidence which are 0.58 and 0.87 m, respectively, whereas the dip of the coal bed up to 20^o does not have significant effect on subsidence. In latter cases, the different preceding scientific papers have been consulted and analyzed for recognizing various influencing factors of subsidence which replicate that the geology and stratigraphic configuration, structural setting of the coal basin, hydro-geological characteristics, less competent nature of overlying rock body, applied mining method, presence of multi-coal seams, ultra thicken coal seam and so on are the major factors in affecting the subsidence event in the area. Moreover, intensive site investigations revealed similar pattern of subsidence and its associated factors around the mine.     

Modified perspective cylindrical map projection

Some of the famous cylindrical projections are defined by a geometric process that is based on the perspective. This process can be imagined as a semitransparent sphere wrapped by a tube, secant, or tangent, with the same center; then all features of the sphere surface are projected onto the tube surface by light rays from a source in the equatorial plane. Just by changing the light source’s position and tube’s diameter, different maps can result. In every cylindrical perspective projections, distortions are functions of latitude only, thus, the value of distortion is fixed along a parallel (or a small circle). Therefore, distortion isograms are parallels (or small circles), symmetrical in relation of the equator. Consequently, it is suitable for territories having narrow band shape, extended by the equator (or an oblique equator). The proposed projection in this paper introduces another possible adjustment in cylindrical projections, in which axis of cylinder does not pass through the center of the sphere. This may satisfy case, where territories have a closed curve shape. By comparing the distribution of distortions in other famous perspective cylindrical projections (Lambert, stereographic, and central), with that in the proposed modified perspective cylindrical projection, it was found that distribution of area distortion in the proposed projection can be considered better than others. Therefore, in relation to area representation, the modified perspective cylindrical projection can be considered suitable for mapping regions, having shape close to an ellipse.     

Melting of crustal xenoliths within ascending basalt: Example from the Kula volcanic field,western Anatolia,Turkey

During its storage or ascent, basaltic magma inevitably interacts with the surrounding rocks. In this study, schist xenoliths incorporated within ascending basalt are examined. Heating of the xenoliths combined with decompression effect of rapid magma uprise led to dehydration melting of hydrous minerals producing hercynitic spinel, melt, sillimanite and FeTi oxides. The melt is rhyolitic, strongly peraluminous (1.77 < A/CNK < 2.35) and corundum normative. It may contain up to 8 wt%FeO_t. It occurs between the foliation planes and in the intragranular environment. Dehydration melting of micas in the schist is probably related to combined effects of heating by basaltic magma and decompression due to the rapid rise. Melting of xenoliths was a progressive process at low pressure. To cite this article: H. Bayhan et al., C. R. Geoscience 338 (2006).     

New photoelectric observations and light curve analysis of 44i bootis

The eclipsing binary 44i Boo was observed photoelectrically using the 40 cm Cassegrain telescope at the Al-Battani Observatory.The light curves were analysed using Fourier techniques of light changes in the frequency-domain, and new geometrical and physical elements have been obtained.A new active period to be started in 1986 has been observed.     

Fuzzy algorithm for estimating average breach widths of embankment dams

Dam breach width significantly influences peak breach outflow, inundation levels, and flood arrival time, but uncertainties inherent in the prediction of its value for embankment dams make its accurate estimation a challenging task in dam risk assessments. The key focus of this paper is to provide a fuzzy logic (FL) model for estimating the average breach width of embankment dams as an alternative to regression equations (RE). The FL approach is capable of handling nonlinear behavior, imprecision in discrete measurements, and parameter uncertainty. Historical data from 69 embankment dam failures are used in the development and testing of the FL model. Application of the FL model is also presented for estimating average breach widths of two case studies that have adequately documented data. The accuracy of the FL rule-based model is investigated using uncertainty analysis: the mean prediction error between the FL estimates and the observed average breach widths is very small (=0.03) and comparable to that achieved using the best available RE. Moreover, the FL uncertainty band is found to be approximately ±0.51 order of magnitude smaller than the ±0.56 order of magnitude achieved with the best available RE. The simulation results indicate the potential of the FL model to be used as a predictive tool for estimating the average breach width of embankment dams.     

Geometry and origin of folding in the Neogene sediments of the Gediz Graben,western Anatolia,Turkey

Abstract

A close relationship between formation of approximately upright folds with axes normal to the extension direction and ramp/flat extensional geometries is established for well exposed Neogene syn-extensional rocks on the presently low-angle Gediz detachment fault, along the southern margin of the Gediz Graben region of western Anatolia, Turkey. Three unconformity-bounded sedimentary sequences and several metamorphic extensional allochthons were mapped in the upper-plate of the Gediz detachment. The oldest sedimentary sequence consists of deformed and folded strata of sandstones and conglomerates that are regarded as being deposited in a supra-detachment basin during the Miocene-Early Pliocene. This unit rests unconformably on the extensional allochthonous, but directly in fault contact with the lower-plate mylonitic rocks. The younger slightly tilted Late Pliocene-Pleistocene sedimentary sequences are post-detachment units that are controlled by EW-trending high-angle normal faults. The youngest alluvium comprises the undeformed present-day basin fill of the Gediz Graben. The supra-detachment sedimentary rocks contain a number of kilometric-scale longitudinal folds that are nearly parallel to the east-west-trending fault system of the Gediz Graben. The folds have a steeply inclined bisecting surface, an interlimb angle of 130–150°, and a plunge of <10°. These folds may be interpreted to form as a result of bending in the underlying Gediz detachment fault. The bending may have an alternation of ramp and flat geometries on which a hanging-wall syncline and rollover anticline formed, respectively. This study again shows the importance of local geology in understanding of some spectacular structures of the extensional basins. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.     

Efficiency of standardized image processing in the fragmentation prediction in the case of Sungun open-pit mine

The paper proposes a standardized image-processing procedure with the use of sieve analysis results for calibration which is utilized to measure the size distribution of fragmentation at Sungun mine. Through this procedure, a number of 19 bench blasting in various levels have been initially selected as the target of the study for each, multiple photos were taken immediately after blast from suitable perspectives and locations of the muckpiles surfaces. The number of image sampling was chosen adequately high to achieve further reliability of the whole photography procedure. Then fragments of each muckpile were separately mixed by a loader, where another image sampling from these new muckpiles, bucket of loaders, and haulage trucks was performed. For the purpose of sieve analysis, seven sieves with the mesh sizes between 1.27 cm (0.5 in) and 25.4 cm (10 in) were designed, manufactured, and then installed at Sungun semi-industrial laboratory. Additionally, three mass samples of the mixed fragments were randomly chosen among the 19 muckpiles for sieving. During image analysis stage, “sieve shift” and “mass power” factors, required to obtain standardized size distribution, were precisely assigned when the results obtained by the image analysis software was in accordance with the sieving results. In order to validate the reliability of the image processing, a comparative analysis of the achieved results was made with the results of the original Kuz–Ram model [Cunningham (1983) The Kuz–Ram model for prediction of fragmentation from blasting. In: Proceedings of the first international symposium on rock fragmentation by blasting, Lulea, Sweden, pp 439–454]. Finally, the image-processing procedure was found to be more efficient, with results close-matched to the real results of the sieve analysis.     

Risk assessment of soil erosion in semi-arid mountainous watershed in Saudi Arabia by RUSLE model coupled with remote sensing and GIS

Soil erosion is the most important factor in land degradation and influences desertification in semi-arid areas. A comprehensive methodology that integrates revised universal soil loss equation (RUSLE) model and GIS was adopted to determine the soil erosion risk (SER) in semi-arid Aseer region, Saudi Arabia. Geoenvironmental factors viz. rainfall (R), soil erodibility (K), slope (LS), cover management and practice factors were computed to determine their effects on average annual soil loss. The high potential soil erosion, resulting from high denuded slope, devoid of vegetation cover and high intensity rainfall, is located towards the north western part of the study area. The analysis is investigated that the SER over the vegetation cover including dense vegetation, sparse vegetation and bushes increases with the higher altitude and higher slope angle. The erosion maps generated with RUSLE integrated with GIS can serve as effective inputs in deriving strategies for land planning/management in the environmentally sensitive mountainous areas.     

Seismic failure probability of concrete slab on CFR dams with welded and friction contacts by response surface method

In this study, failure probability of the concrete slab on concrete-faced rockfill (CFR) dams with welded and friction contact is investigated under earthquake effects by reliability analysis. For this purpose, Torul CFR dam is selected as an example and numerical solutions are performed by considering combination of reliability analysis–finite element method. 1992 Erzincan earthquake acceleration record is used in the finite element analysis considering deconvolved-base rock input model. In this model, the ground motion to be applied to the foundation base rock is obtained by deconvolution of the free-field surface record. In the materially nonlinear analysis, Drucker–Prager model is used for concrete slab and multi-linear kinematic hardening model is utilized for rockfill. Geometrically nonlinearity is also taken into account. Viscous boundary conditions are defined in the finite element model for both foundation soil and reservoir water. The hydrodynamic pressure of the reservoir water is considered using 2D fluid finite elements based on the Lagrangian approach. Both welded contact and friction contact based on the Coulomb’s friction law are defined in the structural connections. Improved Rackwitz–Fiessler method is used with response surface method in the reliability analysis. The tensile and compression strengths of the concrete slab are utilized in the implicit limit state functions considering various thicknesses. The probability of failure of the most critical points in the concrete slab is obtained. According to this study, the probabilities of failure obtained from the CFR dam including friction contact are lower. When the welded contact is considered in joints, the probability of failure of the concrete slab is 1 due to tensile stress limit state and compression stress limit state only if concrete slab is linear. The most critical probability of failure of the concrete slab appears in the case that the concrete slab is linear and rockfill is materially nonlinear. The probability of failure of the concrete slab decreases if the nonlinearity of the concrete is considered. Also, hydrodynamic pressure decreases the reliability of the concrete slab.