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991.
Gustav Grimstad Mohammad Ali Haji Ashrafi Samson Abate Degago Arnfinn Emdal Steinar Nordal 《Geomechanics and Geoengineering》2016,11(1):86-93
Settlement analysis of field cases is normally studied based on parameters interpreted from laboratory samples influenced by varying degrees of sample disturbance. Such disturbance is more pronounced in natural soft clays and could significantly affect the engineering properties of the soil, e.g. the over consolidation ratio (OCR) and compressibility index (Cc). Hence, it is vital to understand the role of sample quality in relation to soil characterisation for long-term settlement analyses. In this work, this is numerically illustrated by use of a simple creep model along with realistic parameter selection. This work takes its starting point on critical discussion of the work presented by Fatahi et al. (2013) and uses the opportunity to further clarify some important aspects of settlement/creep analyses in light of sample quality and parameter interpretation valid for the corresponding constitutive model. 相似文献
992.
Mohammad Maleki Xavier Emery Alejandro Cáceres Diniz Ribeiro Evandro Cunha 《Computational Geosciences》2016,20(5):1013-1028
This work addresses the problem of delineating the spatial layout of ten rock type domains in an iron ore body and of assessing the uncertainty in the domain boundaries. A stochastic approach is proposed to this end, based on truncated Gaussian simulation, which consists in defining successive partitions of the space that comply with the desired spatial continuity and contact relationships between rock type domains. The sequencing of these domains is driven by their position (surficial vs. underlying rocks), granulometry (compact vs. friable rocks), and grades (rich vs. poor) of iron, alumina, manganese and loss on ignition. A total of 100 realizations are produced, conditioned to available drill hole data, and used to quantify the uncertainty in the occurrence of each rock type domain, at both global and local scales. 相似文献
993.
Mohammad Imran Malik M. Sultan Bhat Shahnaz Ahmad Najar 《Journal of the Geological Society of India》2016,87(6):716-726
The valley of Kashmir is blessed with abundant water resources. However, high population growth and concentration of population at favorable locations have resulted in increased demand for water. The problem is further aggravated in Lidder catchment where unplanned tourism development has resulted in deterioration of water quality. Multi-Criteria Evaluation (MCE) approach is adopted using IRS P6 LISS III satellite data 2010, geological map published by Geological Survey of India, toposheets prepared by Survey of India, 1961 and field observation. Seven thematic layers (slope, lineament density, drainage density, soil, geology, geomorphology and land use land cover) are generated in GIS environment and weighted according to their relative relevance to groundwater occurrence. Knowledge-based weights and ranks are normalized, and a weighted linear combination technique is adopted to determine the groundwater potential (GWP). The catchment is divided into five zones of very high, high, medium, low and very low GWP. The results show that 50.22% of the total catchment area, which is uninhabited, has very low GWP. However, the densely populated southern part of the catchment has moderate to very high GWP. The study demonstrates that MCE using remote sensing and GIS technology could be efficiently employed as a very useful tool for the assessment and management of groundwater resources especially in regions where data is poor. 相似文献
994.
Formation of point bars through rising and falling flood stages: Evidence from bar morphology,sediment transport and bed shear stress 下载免费PDF全文
Flow processes and sediment transport in a channel bend and associated point bar have been studied in modern rivers, theoretical models and physical experiments: however, the relationship between flow process and point‐bar morphology has rarely been explained due to the complex nature of open channel flow. Plan‐view exposures of an ancient point‐bar complex, exposed at the top of the Cretaceous Ferron Sandstone Member of the Mancos Shale Formation, south‐central Utah, allowed reconstruction of bar morphology, sediment transport and bed shear stress, which were used to extrapolate flow processes. Studies of these outcrops show that compound point bars and scroll bars were probably formed during falling and rising flood stages, respectively. A simulation model of plan‐view channel form shows that channel dimensions, such as radius of curvature and sinuosity of the point‐bar complex, range between 205 m and 351 m and 1·04 and 1·22, respectively, throughout the evolution of the channel bend. Variations in strength of the helical flow were interpreted as the main control on facies architecture and bar morphology. Strong helical flow was related to the deposition of the scroll bars, while strength of helical flow is decreased for compound bars. The use of cross‐beds as a common palaeocurrent indicator was found to be inconsistent with mean flow directions and channel margin orientation. 相似文献
995.
Diagenetic alterations of the upper Jurassic scleractinian corals,Hanifa Formation,Jabal Al-Abakkayn,central Saudi Arabia 总被引:1,自引:0,他引:1
Mohammad E. Al-Dabbagh Abdelbaset S. El-Sorogy 《Journal of the Geological Society of India》2016,87(3):337-344
During diagenetic stages, the aragonitic skeletons and the inter/intra-corallite cement of the upper Jurassic corals of Hanifa Formation either dissolved or subjected to diagenetic alterations including cementation, micritization, recrystallization, silicification, dolomitization and dedolomitization. The proposed sequence of diagenetic stages is as follows: early marine diagenesis, early meteoric and mixing zone diagenesis, late meteoric diagenesis, and shallow burial diagenesis. Each stage is characterized by certain diagenetic processes. The source of sulfate solutions for dedolomitization in the studied corals is the dissolved anhydrite deposits of the Arab–Hith Formations, sometime before their erosion. A possible source of silica, needed for the formation of chert and chalcedony, is the sponge spicules dispersed in many carbonates of the Hanifa Formation. 相似文献
996.
997.
Nima Akbari Paydar Mohammad Mehdi Ahmadi 《Geotechnical and Geological Engineering》2016,34(6):1857-1876
The use of shear wave velocity (V s) measurements as an in situ test for evaluation of liquefaction potential has increased substantially due to its advantages. Relatively large numbers of studies have been performed to establish the correlation between V s and liquefaction resistance (CRR) of clean sands. Usually, natural sands contain silt and/or clay, and previous studies have shown that both the amount of fines and their nature influence the values of CRR as well as V s. Therefore, the CRR–V s correlations may also be affected by fines content and type of sandy soils. However, effect of fines content and especially fines type of sandy soils on the correlation between V s and CRR is inadequately addressed in the literature. In this study, cyclic triaxial and bender element tests were conducted on samples of sand containing various amounts of different types of fines, and the effects of fines on the values of CRR and V s are investigated. The results show that G 0 and CRR reduce even when small amounts of fines are added to sand. Therefore, use of plasticity index (PI) of the fines fraction is better than the PI of the overall soil when trying to assess the effects of fines. Using obtained experimental data as well as the established semiempirical CRR–V s relationship, the CRR–V s correlation was developed for all the tested soils, and the effect of fines type on the correlation is also examined. Based on the results obtained in this study, CRR–V s correlation is affected by both the amount and the plasticity of the fines present in the sand, and this correlation is soil specific. 相似文献
998.
999.
Elahe Khesali Mohammad Javad Valadan Zoej Mehdi Mokhtarzade Maryam Dehghani 《Journal of the Indian Society of Remote Sensing》2016,44(1):21-29
Two new methods for fusion of high-resolution optical and radar satellite images have been proposed to extract roads in high quality in this paper. Two fusion methods, including neural network and knowledge-based fusion are introduced. The first proposed method consists of two stages: (i) separate road detection using each dataset and (ii) fusion of the results obtained using a neural network. In this method, the neural networks are separately applied on high-resolution IKONOS and TerraSAR-X images for road detection, using a variety of texture parameters. The outputs of two neural networks, as well as the spectral features of optical image, are used in a third neural network as inputs. The second method is a knowledge-based fusion using thresholds of narrow roads and vegetation gray levels. First roads are extracted from each source separately. The outputs are then compared and advantages and disadvantages of each data source are investigated . The results obtained from accuracy assessment show the efficiency of the proposed methods. Furthermore, the comparison of the results showed the superiority of the first algorithm. 相似文献
1000.