Shear Behavior of Sand–Silt Mixtures: A Laboratory Investigation of Coastal Silty Sand Soils of Mostaganem     

Mohammed Derkaoui  Karim Bendani  Fethi Belhouari 《Marine Georesources & Geotechnology》2016,34(7):668-680

In recent years, interest in understanding the mechanisms of mechanical instability of porous media, leading to catastrophic failure has been continuously revised to include, new porous media parameters generating the phenomenon of liquefaction under static or dynamic loadings. Results from experimental test programs have concluded too many physical concepts based on material intrinsic properties, initial states, and other characteristics. Despite the great progress on the subject, these concepts do not allow a unified treatment of such porous media. The assessment of critical shear strength of sandy soils as porous media under undrained conditions is a major challenge in stability analysis. Such strength serves to evaluate the occurrence of flow deformation under liquefaction phenomena. The determination of the critical undrained strength is essentially fundamental for the design of soil structures such as earth dams, bridge supports, building foundations as well as soil densification process to avoid catastrophic failure due to soil instability manifested by failure or large displacement such as settlement. In this work, experimental program on reconstituted loose and medium dense specimens of terrigenous silica sands with different specified fine contents was carried out to analyze its mechanical behavior under undrained conditions. The present article is an attempt to experimentally describe mechanical behavior and theoretically justify such response of loose and medium dense sand by means of critical state soil parameters.  相似文献   

Water fluxes and their control on the terrestrial carbon balance: Results from a stable isotope study on the Clyde Watershed (Scotland)     

J.A.C. Barth  H. Freitag  H.J. Fowler  A.P. Smith  C. Ingle  A. Karim 《Applied Geochemistry》2007,22(12):2684

The gradients between precipitation and runoff quantities as well as their water isotopes were used to establish a water balance in the Clyde River Basin (Scotland). This study serves as an example for a European extreme with poorly vegetated land cover and high annual rainfall and presents novel water stable isotope techniques to separate evaporation, interception and transpiration with annual averages of 0.029 km³ a⁻¹, 0.220 km³ a⁻¹ and 0.489 km³ a⁻¹, respectively. Transpiration was further used to determine CO₂ uptake of the entire basin and yielded an annual net primary production (NPP) of 352 × 10⁹ g C (Giga gram) or 185.2 g C m⁻². Compared to other temperate areas in the world, the Clyde Basin has only half the expected NPP. This lower value likely results from the type of vegetation cover, which consists mostly of grasslands. Subtracting the annual heterotrophic soil respiration flux (R_h) of 392 Gg (206.1 g C m⁻² a⁻¹) from the NPP yielded an annual Net Ecosystem Productivity (NEP) of −40 Gg C, thus showing the Clyde Watershed as a source of CO₂ to the atmosphere. Despite the unusual character of the Clyde Watershed, the study shows that areas with predominant grass and scrub vegetation still have transpirational water losses that by far exceed those of pure evaporation and interception. This infers that vegetation can influence the continental water balances on time scales of years to decades.  相似文献   

A nonlinear polar coordinate shallow water model for tsunami computation along North Sumatra and Penang Island     

Gauranga Deb Roy  Md. Fazlul Karim  Ahmad Izani M. Ismail 《Continental Shelf Research》2007

A nonlinear shallow water model in cylindrical polar coordinate system is developed, using an explicit finite difference scheme with a very fine resolution, to compute different aspects of tsunami at North Sumatra and the adjacent island Simeulue in Indonesia, and the Penang Island in Peninsular Malaysia. The pole of the frame is placed on the mainland of Penang (100.5°E) and the model area extends up to the west of Sumatra (87.5°E). The model is applied to simulate the propagation of tsunami wave towards North Sumatra, Simeulue and Penang Islands associated with Indonesian tsunami of 26 December 2004. The model is also applied to compute water levels along the coastal belts of those islands. Computed and observed water level data are found to be in good agreement and North Sumatra is found to be vulnerable for very high surges. The computed and observed arrival times of high surges are also in reasonable agreement everywhere. Further studies are carried out to investigate the effect of convective terms and it is found that their effects are insignificant in tsunami propagation and weakly significant for wave amplitude very near to the coast.  相似文献   

Mesures in situ par infiltrométrie des propriétés hydrodynamiques des sols de Mnasra (Maroc)     

Karim Tamoh  Abdellatif Maslouhi 《Comptes Rendus Geoscience》2004,336(6):535-545

The aim of this work is the field hydraulic characterisation of Mnasra soils in northern Morocco, which represents an essential step to study the hydraulic and chemical transports through the vadose zone. We have used a tension infiltrometer associated with a transient axisymmetric infiltration method to determine the hydraulic conductivity, which reduces the duration of measurements. This allows us to characterise a large area with many measurements. Parameters of the characteristic functions K(h) and θ(h) are estimated for six different soils belonging to two geomorphologically different domains: a sandy zone and an alluvial plain. To cite this article: K. Tamoh, A. Maslouhi, C. R. Geoscience 336 (2004).  相似文献   

Assessing the potential underestimation of sediment and nutrient loads to the Great Barrier Reef lagoon during floods     

Wallace J  Karim F  Wilkinson S 《Marine pollution bulletin》2012,65(4-9):194-202

Much of the sediment and nutrient load to the Great Barrier Reef (GBR) lagoon happens during over bank floods, when discharge can be significantly underestimated by standard river gauges. This paper assesses the potential need for a flood load correction for 28 coastal rivers that discharge into the GBR lagoon. For each river, daily discharge was divided into flows above and below a 'flood' threshold to calculate the mean annual percentage flow above this threshold. Most GBR rivers potentially need a flood load correction as over 15% of their mean annual flow occurs above the minor flood level; only seven rivers need little/no correction as their flood flows were less than 5% of the mean annual flow. Improved assessment of the true load of materials to the GBR lagoon would be an important contribution to the monitoring and reporting of progress towards Reef Plan and associated marine load targets.  相似文献   

Contributions from Particles in Europe (PiE) 2010, Villefranche-sur-Mer,France: an introduction     

Ole?A.?MikkelsenEmail author  Malik?Chami  David?Doxaran 《Geo-Marine Letters》2012,32(2):85-87

This special issue of Geo-Marine Letters presents selected contributions from the international conference Particles in Europe (PiE) 2010 organized by Sequoia Scientific, Inc., and the Laboratoire d’Océanographie de Villefranche (LOV) on 15–17 November 2010 in Villefranche-sur-Mer, France, and guest-edited by Ole Mikkelsen, Malik Chami and David Doxaran. PiE was initiated in 2008, in order to promote and further our understanding of the importance of suspended particulate matter (SPM) for a very wide range of processes in the aquatic environment—from optics and acoustics, over sediment transport, to the global carbon balance. The papers in this special issue are in particular concerned with the interaction between SPM and water optical properties, as well as how to use optical proxy measurements to understand SPM processes. The next PiE conference is scheduled for 17–19 October 2012 in Barcelona, Spain.  相似文献   

Adsorption of Brilliant Green Dye on Biochar Prepared From Lignocellulosic Bioethanol Plant Waste          下载免费PDF全文

Muhammad Saif Ur Rehman  Ilgook Kim  Naim Rashid  Malik Adeel Umer  Muhammad Sajid  Jong‐In Han 《洁净——土壤、空气、水》2016,44(1):55-62

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Phytoremediation Potential of Hemp (Cannabis sativa L.): Identification and Characterization of Heavy Metals Responsive Genes          下载免费PDF全文

Rafiq Ahmad  Zara Tehsin  Samina Tanvir Malik  Saeed Ahmad Asad  Muhammad Shahzad  Muhammad Bilal  Mohammad Maroof Shah  Sabaz Ali Khan 《洁净——土壤、空气、水》2016,44(2):195-201

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Distribution,Risk Assessment,and Source Identification of Heavy Metals in Surface Sediments of River Soan,Pakistan          下载免费PDF全文

Summya Nazeer  Muhammad Zaffar Hashmi  Riffat Naseem Malik 《洁净——土壤、空气、水》2016,44(9):1250-1259

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Four major unknown active faults identified,using satellite data,in India and Pakistan portions of NW Himalaya     

Shah  A. A.  Malik  Javed N. 《Natural Hazards》2017,88(3):1845-1865

Natural Hazards - New mapping through geomorphic analysis of tectonic landforms using a variety of freely available satellite data, including shuttle radar topography and Google Maps, has revealed...  相似文献