The combined effect of clay and moisture content on the behavior of remolded unsaturated soils   总被引：2，自引：0，他引：2  

Naser A. Al-Shayea 《Engineering Geology》2001,62(4):319-342

The behavior of unsaturated clayey soil is highly influenced by the coupled interaction between water and clay content. Various aspects of the behavior of artificial clay–sand mixtures with variable water content were experimentally studied. Laboratory tests were utilized for the determination of consistency limits, the stress–strain relationship, strength parameters, hydraulic conductivity, and volume change characteristics for various combinations of water and clay content in soil mixtures.

Results presented for various clay–sand mixtures include: new normalized consistency limits; the combined effect of clay content and water content on the stress–strain relationship and on the strength parameters (c and φ); and the effect of clay content on hydraulic conductivity and swelling potential. The cohesion of clayey sand is found to increase with increasing water content to a certain limit, above which it decreases. The angle of internal friction for clayey sand is found generally to decrease with increasing water content. The degree of saturation is found to be better than the water content in explaining the strength behavior. The hydraulic conductivity sharply decreases with increasing clay content up to 40% beyond which the reduction becomes less significant. Simple empirical equations are proposed for predicting the swelling potential of clayey soils as a function of either the clay content or plasticity index.  相似文献   

Stability of columns subjected to earthquake support motion     

Naser Mostaghel 《地震工程与结构动力学》1974,3(4):347-352

The problem of stability of an initially straight, simple column which is subjected to dynamic overload due to the vertical component of ground acceleration during an earthquake is considered. The time history of this component of earthquake, its maximum absolute amplitude and a Liapunov's function are used to define a sufficient condition under which the column will always be stable. It is shown for the case of a simple column that this condition implies that the column will be stable as long as the maximum load which the column is subjected to is less than the Euler buckling load during an earthquake.  相似文献   

A New Approach for Regional Groundwater Level Simulation: Clustering,Simulation, and Optimization     

Kayhomayoon  Zahra  Ghordoyee Milan  Sami  Arya Azar  Naser  Kardan Moghaddam  Hamid 《Natural Resources Research》2021,30(6):4165-4185

Natural Resources Research - In this study, a new 3-stage approach that consists of clustering, simulation, and optimization stages is proposed for the simulation of groundwater level (GWL) in an...  相似文献   

Fatigue damage in randomly vibrating jack-up platforms under non-Gaussian loads     

Sayan Gupta  Naser Shabakhty  Pieter van Gelder   《Applied Ocean Research》2006,28(6):407-419

The problem of fatigue damage estimation of ageing jack-up platforms is considered, using theories of random processes. The sea-wave excitations are modelled as stationary, Gaussian random processes, with specified power spectral density function. The loads acting on the structure due to the sea waves is calculated using Morison’s equation and are therefore non-Gaussian whose probabilistic properties are not available in explicit form. Assuming linear structure behaviour, the probabilistic properties of the structure response are determined using theories of random vibrations. The simple peak counting method is adopted for estimating the mean fatigue damage. This requires knowledge of the joint probability density function of the structure response and its first and second time derivatives, at the same time instant. A methodology has been presented for developing analytical expressions for this joint pdf. This requires evaluation of multidimensional integrals. A recently developed computational algorithm is presented to deal with integrals for which derivation of closed form analytical expressions may not be feasible. The methodology proposed in this paper provides an alternative and computationally cheaper technique for estimating the fatigue damage in comparison to the Monte Carlo simulation procedure. Numerical results have been presented for illustration of the proposed methodology.  相似文献   

Inherent heterogeneity of sediments in Dhahran, Saudi Arabia — a case study     

Naser A. Al-Shayea   《Engineering Geology》2000,56(3-4):305-323

The behavior and properties of sediments depend on their compositional characteristics and formation processes, as well as the environmental conditions during their geological history, i.e. post-formation processes. A vertical cut made in a hill in Dhahran, Saudi Arabia, reveals a vivid picture of the inherent heterogeneity of sediments that have been deposited at different geological ages. A review of the geology of the area, as well as laboratory tests, help to determine the possible causes of the variability of soil types and properties in the area. Laboratory tests include basic geotechnical tests, chemical tests, X-ray diffraction analysis, scanning electron microscopy, and thermal analysis. These tests are used to identify different rock types and soils from the face of the cut. The results of this study indicate that the material from this cut varies from clayey shale and limestone rock (Tertiary, lower Eocene) formed some 52 M.Y. to calcite-cemented sand and pure calcite rock formed in the Quaternary age.  相似文献   

Programed oil generation of the Zubair Formation, Southern Iraq oil fields: results from Petromod software modeling and geochemical analysis     

Thamer Khazal Al-Ameri  Janet Pitman  Madhat E. Naser  John Zumberge  Hiba Adil Al-Haydari 《Arabian Journal of Geosciences》2011,4(7-8):1239-1259

1D petroleum system modeling was performed on wells in each of four oil fields in South Iraq, Zubair (well Zb-47), Nahr Umr (well NR-9), West Qurna (well WQ-15 and 23), and Majnoon (well Mj-8). In each of these fields, deposition of the Zubair Formation was followed by continuous burial, reaching maximum temperatures of 100°C (equivalent to 0.70%Ro) at depths of 3,344–3,750 m of well Zb-47 and 3,081.5–3,420 m of well WQ-15, 120°C (equivalent to 0.78%Ro) at depths of 3,353–3,645 m of well NR-9, and 3,391–3,691.5 m of well Mj-8. Generation of petroleum in the Zubair Formation began in the late Tertiary, 10 million years ago. At present day, modeled transformation ratios (TR) indicate that 65% TR of its generation potential has been reached in well Zb-47, 75% TR in well NR-9 and 55-85% TR in West Qurna oil field (wells WQ-15 and WQ-23) and up to 95% TR in well Mj-8, In contrast, younger source rocks are immature to early mature (<20% TR), whereas older source rocks are mature to overmature (100% TR). Comparison of these basin modeling results, in Basrah region, are performed with Kifle oil field in Hilla region of western Euphrates River whereas the Zubair Formation is immature within temperature range of 65–70°C (0.50%Ro equivalent) with up to 12% (TR?=?12%) hydrocarbon generation efficiency and hence poor generation could be assessed in this last location. The Zubair Formation was deposited in a deltaic environment and consists of interbedded shales and porous and permeable sandstones. In Basrah region, the shales have total organic carbon of 0.5–7.0 wt%, Tmax 430–470°C and hydrogen indices of up to 466 with S2?=?0.4–9.4 of kerogen type II & III and petroleum potential of 0.4–9.98 of good hydrocarbon generation, which is consistent with 55–95% hydrocarbon efficiency. These generated hydrocarbons had charged (in part) the Cretaceous and Tertiary reservoirs, especially the Zubair Formation itself, in the traps formed by Alpine collision that closed the Tethys Ocean between Arabian and Euracian Plates and developed folds in Mesopotamian Basin 15–10 million years ago. These traps are mainly stratigraphic facies of sandstones with the shale that formed during the deposition of the Zubair Formation in transgression and regression phases within the main structural folds of the Zubair, Nahr Umr, West Qurna and Majnoon Oil fields. Oil biomarkers of the Zubair Formation Reservoirs are showing source affinity with mixed oil from the Upper Jurassic and Lower Cretaceous strata, including Zubair Formation organic matters, based on presentation of GC and GC-MS results on diagrams of global petroleum systems.  相似文献   

The effects of agricultural practice and land-use on the distribution and origin of some potentially toxic metals in the soils of Golestan province, Iran   总被引：1，自引：0，他引：1  

Naser Hafezi Moghaddas  Hadi Hajizadeh Namaghi  Hadi Ghorbani  Behnaz Dahrazma 《Environmental Earth Sciences》2013,68(2):487-497

Soil samples were collected from the agricultural lands of Golestan province, north of Iran and analyzed for 24 elements including eight toxic metals of As, Cd, Co, Cr, Cu, Pb, Se and Zn. Electrical conductivity, pH, organic matter, soil texture, calcium carbonate content as well as soil cation exchange capacity were also determined. The possible sources of metals are identified with multivariate analysis such as correlation analysis, principal component analysis (PCA), and cluster analysis. In addition, enrichment factors were used to quantitatively evaluate the influences of agricultural practice on metal loads to the surface soils. The PCA and cluster analysis studies revealed that natural geochemical background are the main source of most elements including Al, Co, Cr, Cs, Cu, Fe, K, Li, Ni, Pb, V and Zn in the arable soils of the province (more than 90 %), however, those soils which have been developed on the mafic and metamorphic rocks were considerably contributed on metal concentration (43 %). Calcium and Sr were constituents of calcareous rocks and Na and S were mainly controlled by saline soils in the north of the province. Loess deposits was also accounting for high levels of selenium concentration. Phosphorous was mostly related to application of P-fertilizers and organophosphate pesticides. The comparison of metal load and enrichment factor for dry and irrigated farmlands showed that Cd, Co, Pb, Se and Zn had higher concentrations in the irrigated lands where considerable amounts of agrochemicals had been applied. However, it also found that proximity of arable lands to urban and industrial areas resulted in higher Pb and Cd values in the irrigated agricultural sources relative to dry ones.  相似文献   

Bounds on earthquake response of elastic columns     

Goodarz Ahmadi  Naser Mostaghel 《地震工程与结构动力学》1982,10(6):769-777

The dynamics of an elastic column subjected to vertical as well as horizontal ground acceleration during an earthquake strong motion is considered. The Liapunov method of stability analysis is employed and several bounds on the maximum lateral displacement and bending stress are obtained and discussed.  相似文献   

Soil organic carbon pools in particle-size fractions as affected by slope gradient and land use change in hilly regions, western Iran   总被引：3，自引：3，他引：0  

Parisa Mokhtari KARCHEGANI  Shamsollah AYOUBI  Mohammad Reza MOSADDEGHI  Naser HONARJOO 《山地科学学报》2012,9(1):87-95

This study was conducted to explore the effects of topography and land use changes on particulate organic carbon(POC),particulate total nitrogen(PTN),organic carbon(OC) and total nitrogen(TN) associated with different size primary particle fractions in hilly regions of western Iran.Three popular land uses in the selected site including natural forest(NF),disturbed forest(DF) and cultivated land(CL) and three slope gradients(0-10 %,S1,10-30 %,S2,and 30-50%,S3) were employed as the basis of soil sampling.A total of 99 soil samples were taken from the 0-10 cm surface layer in the whole studied hilly region studied.The results showed that the POC in the forest land use in all slope gradients was considerably more than the deforested and cultivated lands and the highest value was observed at NF-S1 treatment with 9.13%.The values of PTN were significantly higher in the forest land use and in the down slopes(0.5%) than in the deforested and cultivated counterparts and steep slopes(0.09%) except for the CL land use.The C:N ratios in POC fraction were around 17-18 in the forest land and around 23 in the cultivated land.In forest land,the silt-associated OC was highest among the primary particles.The enrichment factor of SOC,EC,was the highest for POC.For the primary particles,EC of both primary fractions of silt and clay showed following trend for selected land uses and slope gradients:CL> DF> NF and S3 > S2> S1.Slope gradient of landscape significantly affected the OC and TN contents associated with the silt and clay particles,whereas higher OC and TN contents were observed in lower positions and the lowest value was measured in the steep slopes.Overall,the results showed that native forest land improves soil organic carbon storage and can reduce the carbon emission and soil erosion especially in the mountainous regions with high rainfall in west of Iran.  相似文献   

The ammonite family Parahoplitidae in the Sanganeh Formation of the Kopet Dagh Basin, north-eastern Iran     

Seyed Naser Raisossadat   《Cretaceous Research》2006,27(6):907-922

The Iranian part of the Kopet Dagh Basin is located in north-eastern Iran, where sedimentation was continuous throughout Jurassic to Tertiary times. The ammonite content of the Sanganeh Formation (Lower Cretaceous) has been studied. The following parahoplitid forms have been recorded: Acanthohoplites cf. aschiltaensis, A. cf. bigoureti, A. sp. 1, A. sp. 2, A. spp., Colombiceras sp., Hypacanthoplites cf. anglicus, H. cf. clavatus, H. cf. elegans, H. cf. subrectangulatus, H. uhligi, H. sp., Parahoplites cf. campichii and P. cf. maximus.  相似文献