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81.
Hossein Mirmehrabi Mohammad Ghafoori Gholamreza Lashkaripour Sadegh Tarigh Azali Jafar Hassanpour 《Environmental Earth Sciences》2012,66(2):529-535
Occurrence of hydrogen sulfide gas (H2S) is one of the most important engineering geological hazards during tunneling. Its hazards and consequent challenges are
very difficult and costly to solve. During site investigation, one of the tasks for engineering geologists is prediction and
evaluation of the risk of H2S gas in the underground spaces. In this study, water conveyance tunnel of Aspar, which was excavated in H2S-bearing environments, is discussed. The tunnel is excavated in the hydrocarbon formations. Applied experiments suggest that
geological formations pertaining to hydrocarbon resources are crucial in formation and reservation of H2S gas. This paper briefly discusses hazards and geological sources of H2S, as well as remedial measures for decreasing the risks and problems in excavation of the tunnel. To predict the risk of
H2S gas in the underground spaces, it is possible to use some precursors such as: sulfur springs, organic traces, organic argillaceous
rocks, exposure of H2S odor from fresh surface of rock and smell of H2S during boreholes drilling. Controlling the inflow of groundwater into the excavation, diluting the concentration of H2S, training the personnel and utilization of some proper safety equipment have been used to mitigate risks and problems in
tunnel excavation. 相似文献
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Pathways for Participatory Water Governance in Ashaiman,Ghana: Learning from Institutional Bricolage and Hydrosocial Perspectives 总被引：1，自引：0，他引：1
Coupling a hydrosocial perspective with institutional bricolage, this research considers possibilities for participatory water governance in Ashaiman, a peri-urban settlement of Accra, Ghana. We explore three questions: (1) How do people in Ashaiman evoke ideas or experiences of water in general and water governance in particular? (2) What possibilities currently exist for engaging the community in key water-related decisions? (3) What possibilities exist for enhanced participatory water governance in this context, including potential for and interest in new institutions and engagement processes? Results of qualitative interviews and semistructured observation suggest that a siloed, water-centric approach inadequately captures everyday realities of water as hydrosocial and of existing institutions in Ashaiman. In contrast to “modern water,” we propose that water issues may be more meaningfully addressed as bundled with social welfare. Potential implications and alternative ways of understanding socio-institutional arrangements for participatory water governance are explored. 相似文献
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Early Miocene benthic foraminifera and biostratigraphy of the Qom Formation, Deh Namak, Central Iran
A total of 165 samples were collected from the Qom Formation investigated in a stratigraphic section north of Deh Namak, in Central Iran. From these, 35 genera and 47 species of benthic foraminifera were identified. The age of the studied section is Early Miocene (Aquitanian to Early Burdigalian) based on the occurrence of Borelis melo curdica, Meandropsina anahensis, Meandropsina iranica, Elphidium sp. 14, Peneroplis farsensis, and Triloculina tricarinata. The thickness of the Qom Formation is 401 m of which 161.2 m is early Burdigalian in age. Foraminiferal assemblages in the Deh Namak section are referable to the Borelis melo group-Meandropsina iranica Assemblage Zone and Miogypsinoides-Archaias-Valvulinid Assemblage Zone of [Adams, T.D., Bourgeois, F., 1967. Asmari biostratigraphy. Iranian Oil Operating Companies, Geological and Exploration Division, Report1074 (unpublished) 1–37.] described originally from the Asmari Formation. 相似文献
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Bahi Jalili Seh‐Bardan Radziah Othman Samsuri Ab Wahid Aminudin Husin Fardin Sadegh‐Zadeh 《洁净——土壤、空气、水》2012,40(6):607-614
A column bioleaching experiment was carried out to compare the effectiveness of the fungus Aspergillus fumigatus to bioleach arsenic (As) and heavy metals from the tailings using two different methods. In the first method, which is named as distribution method (DM), the fungus was distributed in the column by means of vertical and horizontal layers of coarse sand. In the other method, named as surface applied method (SAM), the fungus was cultivated on the surface of the tailings, which was covered with a few centimeters of coarse sand. Results showed that in the DM, oxalic acid production was stimulated and maximum removal of As, Fe, Mn, and Zn was 53, 51, 81, and 62%, respectively. However, Pb removal was low (8%), which might be due to the precipitation of Pb as its oxalates. On the other hand, the maximum removal of As, Fe, Mn, Pb, and Zn were 22, 28, 37, 64, and 34%, respectively, for the SAM. Results of the sequential extraction study showed that the DM was effective in removing the water soluble, exchangeable, carbonate, and Fe/Mn oxide fractions of As, Fe, Mn, and Zn. Our study suggested that A. fumigatus has a potential to be used in remediation of heavy metal contaminated sites. Distributing the fungus throughout the entire tailings columns improved the bioleaching of heavy metals by the fungus. 相似文献
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Rehabilitation of earthquake damaged external RC beam‐column joints by joint enlargement using prestressed steel angles 
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下载免费PDF全文 Jalil Shafaei Abdollah Hosseini Mohammad Sadegh Marefat Jason M. Ingham 《地震工程与结构动力学》2017,46(2):291-316
The effectiveness of a rehabilitation method based on joint enlargement using prestressed steel angles to enhance the seismic behavior of damaged external reinforced concrete beam‐column joints was experimentally investigated. Three half‐scale joints having either non‐seismic or seismic reinforcement details were tested both before and after rehabilitation by applying lateral cyclic loading of increasing amplitudes. Two defects were considered for the two non‐seismic units, being the absence of transverse steel hoops and insufficient bond capacity of beam bottom steel reinforcing bars in the joint panel zone. The damaged specimens were rehabilitated by injecting epoxy grout into existing cracks and installing stiffened steel angles at the re‐entrant corners of the beam‐column joint, both above and below the beam, that were mounted and held in place using prestressed high‐tensile strength bars. The test results indicated that the seismic performance of the rehabilitated specimens in terms of strength, stiffness, and ductility was fully recovered and comparable with the performance of the seismically detailed specimen. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Ataollah Kavian Aazam Alipour Karim Soleimani Leila Gholami Pete Smith Jesús Rodrigo‐Comino 《水文研究》2019,33(2):261-270
The drastic growth of population in highly industrialized urban areas, as well as fossil fuel use, is increasing levels of airborne pollutants and enhancing acid rain. In rapidly developing countries such as Iran, the occurrence of acid rain has also increased. Acid rain is a driving factor of erosion due to the destructive effects on biota and aggregate stability; however, little is known about its impact on specific rates of erosion at the pedon scale. Thus, the present study aimed to investigate the effect of acid rain at pH levels of 5.25, 4.25, and 3.75 for rainfall intensities of 40, 60, and 80 mm h?1 on initial soil erosion processes under dry and saturated soil conditions using rainfall simulations. The results were compared using a two‐way ANOVA and Duncan tests and showed that initial soil erosion rates with acidic rain and non‐acidic rain under dry soil conditions were significantly different. The highest levels of soil particle loss due to splash effects in all rainfall intensities were observed with the most acidic rain (pH = 3.75), reaching maximum values of 16 g m?2 min?1. The lowest levels of particle losses were observed in the control plot where non‐acidic rain was used, with values ranging from 3.8 to 8.1 g m?2 min?1. Similarly, under saturated soil conditions, the lowest level of soil particle loss was observed in the control plot, and the highest peaks of soil loss were observed for the most acidic rains (pH = 3.75 and pH = 4.25), reaching maximum average values of 40 g m?2 min?1. However, for saturated soils with acidic water but with non‐acidic rain, the highest soil particle loss was observed for the control plot for all the rainfall intensities. In conclusion, acidic rain has a negative impact on soils, which can be more intense with a concomitant increase in rainfall intensity. Rapid solutions, therefore, need to be found to reduce the emission of pollutants into the air, otherwise, rainfall erosivity may drastically increase. 相似文献
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Cracks are accounted as the most destructive discontinuity in rock, soil, and concrete. Enhancing our knowledge from their properties such as crack distribution, density, and/or aspect ratio is crucial in geo-systems. The most well-known mechanical parameter for such an evaluation is wave velocity through which one can qualitatively or quantitatively characterize the porous media. In small scales, such information is obtained using the ultrasonic pulse velocity(UPV) technique as a non-destructive test. In large-scale geo-systems, however, it is inverted from seismic data. In this paper, we take advantage of the recent advancements in machine learning(ML) for analyzing wave signals and predict rock properties such as crack density(CD) – the number of cracks per unit volume. To this end, we designed numerical models with different CDs and, using the rotated staggered finite-difference grid(RSG) technique, simulated wave propagation. Two ML networks, namely Convolutional Neural Networks(CNN) and Long Short-Term Memory(LSTM), are then used to predict CD values. Results show that, by selecting an optimum value for wavelength to crack length ratio, the accuracy of predictions of test data can reach R2> 96% with mean square error(MSE) < 25e-4(normalized values). Overall, we found that:(i) performance of both CNN and LSTM is highly promising,(ii) accuracy of the transmitted signals is slightly higher than the reflected signals,(iii) accuracy of 2D signals is marginally higher than 1D signals,(iv)accuracy of horizontal and vertical component signals are comparable,(v) accuracy of coda signals is less when the whole signals are used. Our results, thus, reveal that the ML methods can provide rapid solutions and estimations for crack density, without the necessity of further modeling. 相似文献