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61.
This paper presents results of analysis of full-scale pile load test data of 14 piles embedded in either loose or medium dense
sands. The analysis was performed using two methods, p–y curve approach and a more recently developed khmax approach. Comparison of the results obtained using both the methods is also presented. A step-by-step analysis procedure
is presented for predicting lateral load deflection response of single piles in sand using the khmax approach. The results presented show that the khmax approach has promise over the p–y curve approach because of its simplicity and the fact that it provides upper- and lower-bound curves, which are valuable
guides to making engineering decisions. For loose sands, a new range of khmax values is recommended to better predict the lateral load–deflection response of single piles. 相似文献
62.
63.
Realistic models of solar prominence flux ropes are numerically constructed. The models are in 2.5 dimensions, including the effects of non-isothermal temperature, density and gravity, and pressure. Stability of the equilibria to pressure- and gravity-driven instabilities is numerically investigated, using the ballooning formalism of fusion plasma theory. The equilibrium models can become unstable to pressure- and gravity-driven modes at plasma parameters characteristic of prominences. 相似文献
64.
Mohamad Nor Omar Colin Peter Abbiss Mohd. Raihan Taha Khairul Anuar Mohd. Nayan 《Engineering Geology》2011,(4):259
This paper presents a method of calculating long-term settlement of a loaded pad on soft clay at Klang, Selangor, Malaysia where the soil model is treated as an anelastic material of viscoelastic property. Initially, an elastic shear modulus (G) value from shear wave velocity profiles of the seismic tests from spectral analysis of surface wave (SASW) and continuous surface wave (CSW) tests was obtained. A value of damping (D) at an equivalent elastic strain is then calculated from the hysteresis of the plate load tests corrected to equivalent strain using the Damping–Strain formula. The calculated elastic settlement and its equivalent damping are then used to calculate the long-term settlement by applying the generalised viscoelastic formula. Comparisons to traditional methods of settlement predictions were made and the viscoelastic formula has shown better agreement to the observed settlement. Further modification of the settlement formula is introduced to improve the settlement accuracy to 10%. 相似文献
65.
In this study, the hydrogeochemical program PHREEQC was used to determine the chemical speciation and mineral saturation indices (SIs) of groundwater in the vicinity of the proposed high-level nuclear waste repository at Yucca Mountain, Nevada (USA). In turn, these data were used to interpret the origin and recharge mode of groundwater, to elucidate the mechanisms of flow and transport, and to determine potential sources of groundwater contamination. PHREEQC was run to determine aqueous dissolved species and minerals that would be in equilibrium with the study area’s groundwater. Selected major ions, associated SI, F− and Ca/Na ion exchange were then examined using the multivariate statistical methods of principal component factor analysis and k-means cluster analysis. Analysis of dissolved ion concentrations, SIs, and Ca/Na ion exchange allows simultaneous consideration of arithmetic (raw concentrations) and logarithmic (SI, ion exchange) variables that describe the hydrochemical system and, therefore, can provide further insight into the system’s behavior. The analysis indicates that the dominant processes and reactions responsible for the hydrochemical evolution in the system are (1) evaporative concentration prior to infiltration, (2) carbonate equilibrium, (3) silicate weathering reactions, (4) limited mixing with saline water, (5) dissolution/precipitation of calcite, dolomite and fluorite, and (6) ion exchange. Principal component factor analysis and k-means cluster analysis of factor scores allow the reduction of dimensions describing the system and the identification of hydrogeochemical facies and the processes that defined and govern their evolution.Statistical analysis results indicate that the northern, west face and southern Yucca Mountain groundwater is fresh water with low concentrations of Ca2+, Mg2+, Cl−, Ca2+/(Na+)2, and CaF2. The Fortymile Wash groundwater is dilute. The carbonate signature is shown in the Ash Meadows and Death Valley waters with high fluorite SI. Finally, the Crater Flat, Stripped Hills, and Skeleton Hills are dominated by Ca/Na ion exchange, Mg and Ca. The hydrochemical and statistical analyses showed three main groundwater signatures or hydrochemical processes indicating groundwater evolution, potential flowpaths, and recharge areas. The flowpaths are the trace of the Amargosa River, the trace of Fortymile Wash, and its convergence with the Amargosa River. This appears to represent not just a groundwater flow path, but traces of surface runoff infiltration as well. 相似文献
66.
Slim Khedhiri Khadija Semhi Joëlle Duplay Fadila Darragi 《Environmental Earth Sciences》2011,62(5):1013-1025
A sequential extraction procedure applied to surface sediments from El Kelbia Lagoon determined the partitioning of Ba, Co,
Cr, Cu, Ni, Sr, V and Zn among evaporites, carbonates, Fe–Mn oxides, organic matter and silicates. To validate the procedure,
the sequential extraction results (SER) were compared to principal components analysis (PCA) using major and trace element
concentrations and mineralogical quantitative data of surface sediments. SER showed that a part of Sr was highly mobile; Cu,
Sr, and Zn and a part of Co and Ni were mobile depending on pH conditions; Cr and V were strongly bound to silicate phases;
Co and Ni were partitioned between carbonates, oxides and silicates, and a great part of Ba and Sr were bound to organic matter
or sulfides. An agreement was found with PCA in terms of partitioning among minerals for most trace elements. Moreover, the
absence of correlation between Ca concentrations and the abundances of calcite, gypsum or dolomite could be explained by an
important fraction of Ca bound to organic matter. Also, unexpected negative correlations between abundances of smectite and
illite could be explained by a transformation of illite into smectite. Thus, SER and PCA were mostly convergent, which enabled:
(1) validation of the extraction procedure used, and (2) refinement of interpretations of the origin and relations between
minerals. 相似文献
67.
A study was carried out on the combination of petrographies, geochemistry (major and trace), weathering and the digenesis of 31 sandstones samples to determine their provenance and depositional tectonic setting of sedimentary basins. Based on the composition of Detrital grains (point counting), most of the Sarah sandstones were classified as quartz arenites types (99% on an average). The petrographic data indicated that the resultant mature sandstones are derived from recycled and craton interior tectonic provenance. Tectonic setting discrimination diagrams based on major elements suggest that sandstones were deposited in a passive margin and polycyclic continental tectonic setting. The relationship between K2O/Na2O ratio and SiO2 showed that the Sarah sandstone samples fall into the passive margin field. The chemical index of alteration (CIA?=?63.84%) of sandstones suggested moderate weathering or reworking in the area. The concentration of trace elements indicates that the sediments were probably derived from the mixed sedimentary-meta sedimentary provenance and changes in sedimentary process due to climatic variations. The main diagenetic events were in the form of cements, which occur as grain coats and as pore fillings. An integrated approach showed that the parent area of paleovalley-fill sediment is probably a complex of granite, metasedimentary and pre-existing sedimentary rocks. 相似文献
68.
Pietro Passerini Marta Marcucci Giovanni Sguazzoni Leonardo Zan Abdourahman Omar Haga 《地学学报》1991,3(6):607-618
Slickenside studies in regions of crustal spreading such as Iceland and the Afar Depression, East Africa, reveal that a significant number of faults parallel and close to rift axes are strike-slip rather than normal. Therefore, the pattern of brittle deformation in these regions does not conform to the classic two-dimensional schemes of oceanic tectonics and pre-oceanic rifting. Dip-slip and strike-slip faulting presumably alternated along or in the vicinity of spreading axes, indicate a varying stress field and a combination of transverse and longitudinal movements. In Iceland, strike-slip faults parallel to rifts are observed both west and east of the rift system as well as in a median area between overlapping rifts; the mechanisms proposed for their origin include accommodation of oblique convergence or divergence of crustal sections due to variations of spreading directions along axis and the interaction of overlapping rifts. In the Afar Depression this kind of fault is recorded west of the rift of Asal and can be imputed to reflect an interaction among rifts in the vicinity of the Afar triple junction. Rift-parallel strike-slip faults cannot however be assumed to be a feature of all crustal spreading axes due to the peculiarity of the examined regions: both of them are hot-spot areas and the Afar Depression lies at a triple junction. 相似文献
69.
Maher Omar Abdallah Shanableh Mohamed Arab Khaled Hamad Ali Tahmaz 《Geotechnical and Geological Engineering》2018,36(6):3467-3483
An essential task in the process of construction is the determination of compaction properties of soils. Many years of laboratory test experience strengthen our belief in the existence of predictive equations that govern the compaction characteristics of soils. An advanced mathematical model developed in this research in order to uncertain the governing equations. An advanced mathematical model developed in this research in order to uncertain the governing equations. Through a comparative study among a Multiple Linear Regression (MLR) model, an Artificial Neural Network (ANN) model, Extreme Learning Machine (ELM) and a Support Vector Machine (SVM) model, the best predicting model was determined. For this purpose, Six hundred and six (606) samples collected and split into a dataset used for training the models and another used for validation of the derived model. 8 neural networks with a varying number of hidden layers and a varying number of nodes in hidden layers were employed. In ELM 1 hidden layer with varying number of units were employed. It was found that the equations derived from the ELM models described the relationship with superiority over multiple regression, ANN and SVM models for Maximum Dry Density and MLR models described the relationship with superiority over ANN, ELM and SVM models for Optimum Moisture Content. 相似文献
70.