Explicit data-driven models for prediction of pressure fluctuations occur during turbulent flows on sloping channels

Stochastic Environmental Research and Risk Assessment - Pressure fluctuations are among the favorite topics for hydraulic engineers due to their critical role in the design and safe operation of...     

Three-dimensional finite element analysis of spatially variable PVD improved ground

A stochastic approach that investigates the effects of soil spatial variability on stabilisation of soft clay via prefabricated vertical drains (PVDs) is presented and discussed. The approach integrates the local average subdivision of random field theory with the Monte Carlo finite element (FE) technique. A special feature of the current study is the investigation of impact of spatial variability of soil permeability and volume compressibility in the smear zone as compared to that of the undisturbed zone, in conjunction with uncoupled three-dimensional FE analysis. A sensitivity analysis is also performed to identify the random variable that has the major contribution to the uncertainty of the degree of consolidation achieved via PVDs. The results of this study indicate that the spatial variability of soil properties has a significant impact on soil consolidation by PVDs; however, the spatial variability of soil properties in the smear zone has a dominating impact on soil consolidation by PVDs over that of the undisturbed zone. It is also found that soil volume compressibility has insignificant contribution to the degree of consolidation estimated by uncoupled stochastic analysis.     

Geochemical characterization of zoned zircon from Wadi Abu Rusheid psammitic gneiss, south Eastern Desert, Egypt

A unique zircon was studied in the gneiss samples collected from the Wadi Abu Rusheid psammitic gneiss using electron scanning microscope and electron probe microanalyses. This zircon can be categorized into two types according to the texture and trace element content: (l) magmatic zircon slightly enriched in HfO₂ with ordinary zone. (2) Overgrowths of zircon occur as two species, the first species being highly enriched in HfO₂ with irregular zoning. The second species is highly enriched in HfO₂ forming a rim around the second species with a very sharp thinner boundary. The first type shows a distinct oscillatory internal zoning pattern without change in shape of this zone and has conspicuous inclusion-free zircon overgrowths with distinct poor concentrations in Y, Hf, Th, U, Nb, and Ta in both rim and core. The second type shows two species, the first one displays distinct irregular interval zoning and irregular overgrowth with abrupt change in composition of these zones with distinct enrichment in Y, Hf, Th, U, Nb, and Ta in the rim relative to the core. The second species is forming a rim around the first species also with distinct enrichment in Y, Hf, Th, U, Nb, and Ta content. These indicate that two events (crystallization environment) have played an important role in the formation of this zircon and largely reflect differences in whole-rock trace element contents between the successive generations of this zircon. The first event is believed to be of magmatic origin giving rise to normal composition of magmatic zircon. The second event shows an intense successive process of metasomatic activity during the formation of the Abu Rusheid radioactive gneiss. Electron microprobe analysis indicates that oscillatory zoned zircon shows poor content of Y, Hf, Th, U, Nb, Ta, and rare earth elements (REE) in the rim and core, while overgrowths of zircon are slightly enriched by these elements. Also, these analyses indicate that the Abu Rusheid psammitic gneiss has been significantly enriched by the thorite mineral (Th content up to 54.72% ThO₂) and columbite-bearing minerals (Nb content up to 64.74% Nb₂O₅, Ta content up to 9.32% Ta2O₅). The poor content of REE in overgrowths of zircon indicates mobilization of REE during the metamorphism processes of gneiss.     

Geology and geochemistry of Tertiary basalt in south Wadi Hodein area, South Eastern Desert, Egypt

Tertiary basalt is widespread in the area south of Wadi Hodein, south Eastern Desert, Egypt. It is the youngest unit in the basement rocks of the Central Eastern Desert classification of El Shazly (Proc 22nd Intl Geol Congr, New Delhi 10:88–101, 1964) and El Ramly (Ann Geol Surv Egypt II:1–17, 1972), traversed all the previous succession of the basement rocks as well as the Nubia Sandstone of Cretaceous age, forming sheets, small hills, ridges, and dikes. This Tertiary basalt is strongly associated with the opening of the Red Sea. Geologic, petrographic, and petrochemical studies as well as microprobe and X-ray analyses were performed on samples from Wadi Hodein Tertiary basalt. Field and petrographic studies classified the Tertiary basalt in south Wadi Hodein into porphyritic olivine basalt, plagiophyric basalt, and doleritic basalt. Opaque minerals (magnetite and ilmenite) constitute 6–7.5% of this basalt. Petrochemical studies and microprobe analyses reveal that they are low-TiO₂ basalt with low uranium and thorium contents, classified as being basaltic andesite to andesite, originated from calc-alkaline magma, and developed in within-plate tectonic environment. Scanning electron microscopy shows that magnetite and ilmenite are the prevalent opaque minerals in this Tertiary basalt. Field radiometric measurements of the Tertiary basalt in south Wadi Hodein reveals low uranium and thorium contents. Uranium contents range from 0.5 to 0.9 ppm, while thorium contents range from 1.2 to 3.2 ppm. Fractional crystallization and mass balance modeling indicate that the most-silica low-TiO₂ Tertiary basalt in south Wadi Hodein can be derived from the relatively less-silica low-TiO₂ Tertiary basalt of south Quseir and Gabal Qatrani through fractional crystallization of plagioclase, olivine, augite, and titanomagnetite oxides. Tertiary basalts in south Wadi Hodein and south Quseir have nearly the same age, 25 Ma (Sherif, The Fifth International Conference on the Geology of Africa, 2007), 24 Ma (Meneisy and Abdel Aal, Ain Shams Sci Bull 25(24B): 163–176, 1984), and 27 Ma (El Shazly et al., Egypt J Geol 1975), respectively. Finally, the fractionation modeling and geochemical characteristics of these basalts suggested their origination from one basaltic magma emplaced in late Oligocene.     

Causes and consequences of recent floods in the Golestan catchments and Caspian Sea regions of Iran

In August 2001, the worst flash flooding event of the Caspian Sea regions in over two centuries claimed over 300 lives after a weekend of heavy rainfall and brought about a devastating disaster in the Mother-Soo catchment, province of Golestan, Iran. As a result of this event, a series of site investigation were carried out to identify the pertinent factors that led to a flood of this magnitude. This paper identifies the fundamental causes of the frequent floods and debris flow occurrence in the area prone to flooding and analyzes the main runoff mechanism of these events. The maximum observed 24-h rainfall depths and maximum peak discharges at the existing gauges were compared with the depths of rainfall and the peak values corresponding to the August 2001 flood respectively. For the majority of the rain gauges, the rainfall depth exceeded those of historical recorded events. In Golestan dam, an increase of 7.5 times the maximum value observed in the past 20 years was noted. The flood height was 10–15 m while passing through the middle subcatchment area of Golestan National Park. The preliminary evaluation indicates the existence of bare soil in the catchment, movable material, steep slopes, high rainfall intensity, deterioration of pasture and forest land, and inappropriate agriculture and development practices as well as climate change were the main factors for the occurrence and the extent of the August 2001 disaster. Finally, due to the likelihood of flooding and debris flow events in future, some countermeasures are proposed.     

ηBoo Inversion of simulated rotational profile

The detection of solar oscillations on ηBoo is now established. We explore here what we can expect from the inversion of similar data by COROT to recover the rotational profile of the star. We show that the observation of a few low-l mixed modes in the excited high frequency range gives access to the rotational gradient if it is large enough.     

Investigation of influence of tunneling on existing building and tunnel: model tests and numerical simulations

To investigate the realistic ground behavior during tunneling, a new device has been developed. With the new device, model tests of tunnel excavation considering an existing tunnel and an existing building were carried out. Non-linear finite element analyses corresponding to the model tests were also conducted using FEMtij-2D software where an elastoplastic subloading t _ij model was used to describe the mechanical behavior of soil. Earth pressure distribution around the tunnels and ground movements during tunnel excavation depend on the distance and position between the twin tunnels. There is a significant effect of tunneling on the existing foundation of building even in the case where the tunnel is constructed in deep underground. The numerical analyses capture well the results of the model tests.     

Soil bio-cementation using a new one-phase low-pH injection method

Acta Geotechnica - Soil bio-cementation via microbially induced carbonate precipitation (MICP) has been extensively studied as a promising alternative technique to traditional chemical cementing...