Experimental Investigation of Frictional Behavior Between Cohesive Soils and Solid Materials Using Direct Shear Apparatus     

Marwa Feligha  Farid Hammoud  Mouloud Belachia  Mohamed Salah Nouaouria 《Geotechnical and Geological Engineering》2016,34(2):567-578

Soil shearing resistance is very important while designing various structures which have direct contact with soil, for example, sheet piles, piles, retaining walls, reinforced earth structures and shallow foundations. Even though designers use empirical values for their design, it is very important to obtain more accurate values for soil–solid materials shearing resistance. In this work, laboratory tests have been carried out to investigate the effect of roughness interface and texture models on friction angle between cohesive soils and steel, as well as abrasive paper material, using direct shear tests. All tests were carried out under consolidated drained shear conditions. The behavior at the soils–solid interface was found to vary according to surface roughness. It also seems that the type of material (steel or paper of abrasive) used does not have a major influence on the shear strength. As far as roughness is concerned, friction behavior is likely to be generally classified into three failure modes, namely full sliding at the interface, shear failure within the soil, and a mixed behavior where interface sliding and shear deformation of the soil specimen proceed simultaneously. However, for the second mode, the shear strength at the interface soil-rough solid materials steel was found to be lower than the shear strength of the soil, for a soil that is classified as high plasticity clay. Furthermore, it was found that the interfacial shear strength is independent of the texture surface for a given roughness.  相似文献   

Formation of vortices in the presence of sheared electron flows in the earth's ionosphere     

T. Farid  P. K. Shukla  P. H. Sakanaka  A. M. Mirza 《Planetary and Space Science》2000,48(15):1505-1511

It is shown that sheared electron flows can generate long as well as short wavelength (in comparison with the ion gyroradius) electrostatic waves in a nonuniform magnetplasma. For this purpose, we derive dispersion relations by employing two-fluid and hybrid models; in the two-fluid model the dynamics of both the electrons and ions are governed by the hydrodynamic equations and the guiding center fluid drifts, whereas the hybrid model assumes kinetic ions and fluid electrons. Explicit expressions for the growth rates and thresholds are presented. Linearly excited waves attain finite amplitudes and start interacting among themselves. The interaction is governed by the nonlinear equations containing the Jacobian nonlinearities. Stationary solutions of the nonlinear mode coupling equations can be represented in the form of a dipolar vortex and a vortex street. Conditions under which the latter arise are given. Numerical results for the growth rates of linearly excited modes as well as for various types of vortices are displayed for the parameters that are relevant for the F-region of the Earth's ionosphere. It is suggested that the results of the present investigation are useful in understanding the properties of nonthermal electrostatic waves and associated nonlinear vortex structures in the Earth's ionosphere.  相似文献   

Geochemical Assessment and Lateral Reservoir Continuity of Asmari Reservoir Oils in the Cheshmeh-Khush Oilfield, SW Iran     

Farid TEZHEH  Bijan BEIRANVAND  Hormuz GHALAVAND  Mohammad Reza KAMALI  Rahim BAGHERI TIRTASHI 《《地质学报》英文版》2020,94(5):1562-1573

A total of 6 oil samples were systematically selected from six Asmari Reservoir wells in the Cheshmeh-Khush Oilfield for geochemical evaluation of the hydrocarbon system, based on reservoir geochemistry and oil fingerprints. An investigation of the distribution patterns of normal alkanes and tricyclic and tetracyclic terpanes along with characteristic biomarkers of the depositional environment and sedimentary facies, indicated that the source rock of the studied hydrocarbons was deposited in a reducing aquatic environment with a low input of terrigenous material and predominantly carbonate lithology derived from organic algal matter. The studied oil samples exhibited moderate maturity, as was further confirmed by the parameters extracted from the light hydrocarbons. Statistical clustering based on different biomarker parameters indicated the presence of two oil families. Additionally, the application of branched and cyclic compounds in the light hydrocarbons (C5–C11) to evaluate lateral continuity of the Asmari reservoir further supported the presence of the two oil families. Other evidence proved the presence of a NE–SW trending fault separating wells X5 and X6 from the other wells in the field. In other wells across the field, good lateral reservoir continuity was observed, despite the presence of faults on the northern and southern plunges of the structure.  相似文献   

Internal erosion in dike-on-foundation modeled by a coupled hydromechanical approach     

Jie Yang  Zhen-Yu Yin  Farid Laouafa  Pierre-Yves Hicher 《国际地质力学数值与分析法杂志》2019,43(3):663-683

One of the major causes of instability in geotechnical structures such as dikes or earth dams is internal erosion, an insidious process that occurs over a long period of time. Research on this topic is still fairly new and much more needs to be understood in order to solve the problems posed by this phenomenon. This paper proposes a hydromechanical model based on porous continuous medium theory to assess how internal erosion impacts the safety of earthen structures. The saturated soil is considered as a mixture of four interacting constituents: soil skeleton, erodible fines, fluidized fine particles, and fluid. The detachment and transport of the fine particles are described by a mass exchange model between the solid and the fluid phases. An elastoplastic constitutive model for sand-silt mixtures has been developed to monitor the effect of the evolution of both porosity and fines content induced by internal erosion upon the behavior of the soil skeleton. The model has been numerically solved with the finite element method. It has then been applied to the specific case study of a dike foundation subjected to internal erosion induced by the presence of a karstic cavity beneath the alluvium layer. The numerical results show the onset of erosion, the time-space evolution of the eroded zone, and the hydromechanical response of the soil constituting the dike, all of which highlights the effects of the cavity location, the erosion rate, and the fines content.  相似文献   

Engineering Properties of Cement Kiln Dust-Modified Soils in Western Washington State     

Kolleen?Carlson  Farid?SariosseiriEmail author  Balasingam?Muhunthan 《Geotechnical and Geological Engineering》2011,29(5):837-844

The Portland cement manufacturing process produces considerable amount of cement kiln dust (CKD). While many facilities are able to reuse a significant portion of CKD in their production lines, a large percentage is removed as industrial waste and placed in landfills. Because of the large amount of material potentially available for use, and in an effort to cut disposal costs, alternative and beneficial uses for CKD need to be investigated. This study presents experimental results of the use of CKD in modification and stabilization of soils from the Aberdeen and Everett areas in the state of Washington. These soils are typically wet of the optimum water content and pose problems during geotechnical construction. CKD was added in percentages of 5, 10, 15, and 20% by dry weight of the soils. Laboratory tests, including drying rate of the soils, Atterberg limits, standard proctor and unconfined compressive strength were conducted. Results of the investigation showed significant improvement in drying rate and unconfined compressive strength of the CKD treated specimens as the percentage of CKD increased. It was also found that lower percentages of CKD can be used for modification purposes, whereas higher percentages of CKD can be used for both modification and stabilization purposes in geotechnical construction.  相似文献   

Mesoproterozoic evolution of the R��o de la Plata Craton in Uruguay: at the heart of Rodinia?     

Claudio Gaucher  Robert Frei  Farid Chemale Jr  Dirk Frei  Jorge Bossi  Gabriela Mart��nez  Leticia Chiglino  Federico Cernuschi 《International Journal of Earth Sciences》2011,100(2-3):273-288

Mesoproterozoic volcanosedimentary units and tectonic events occurring in the Río de la Plata Craton (RPC) are reviewed. A belt consisting of volcanosedimentary successions exhibiting greenschist-facies metamorphism is exposed in the eastern RPC (Nico Pérez Terrane) in Uruguay. The Parque UTE Group consists of basic volcanics and gabbros at the base (1,492?±?4?Ma, U?CPb on zircon), carbonates in its middle part and interbedded carbonates, shales and acid volcanics (1,429?±?21?Ma, U?CPb on zircon) at the top. The Mina Verdún Group is made up of rhyolites and acid pyroclastics at its base and top, and Conophyton-bearing limestones and massive dolostones in the middle. A U?CPb LA-ICP MS zircon age of 1,433?±?6?Ma is reported here for lapilli-tuffs at the base of the Mina Verdún Group (Cerro de las Víboras Formation). This age shows that the Mina Verdún Group immediately postdates the Parque UTE Group, a fact supported by carbon isotope chemostratigraphy. Both units were deformed and metamorphosed between 1.25 and 1.20?Ga, as shown by K?CAr and Ar?CAr ages. This tectonic event affected most of the RPC and led to the accretion of the Nico Pérez Terrane to the remainder of the RPC along the Sarandí del Yí megashear. We report a U?CPb LA-ICP MS zircon age (upper intercept) of 3,096?±?45?Ma for metatonalites of the La China Complex (Nico Pérez Terrane), which yield a lower intercept age of 1,252?Ma. A proto-Andean, Mesoproterozoic belt is envisaged to account for abundant Mesoproterozoic detrital zircon ages occurring in Ediacaran sandstones of the RPC. If the RPC is fringed at both sides by Mesoproterozoic, Grenville-aged belts it is likely that it occupied a rather central position in Rodinia. A possible location between Laurentia and the Kalahari Craton, and to the south of Amazonia, is suggested.  相似文献   

Precursory signals associated with the 2010 M8.8 Bio-Bio earthquake (Chile) and the 2010 M7.2 Baja California earthquake (Mexico)     

Habibeh Valizadeh Alvan  Shattri Mansor  Husaini Omar  Farid H. Azad 《Arabian Journal of Geosciences》2014,7(11):4889-4897

Recently, new theories on underground geophysical and geochemical interactions which had been reported to occur during the preparation stages of earthquakes and the remotely measurable variations have been put to test and some warning factors were suggested as earthquake precursors. Data vendors are providing daily basis information from the earth's surface by combining remote sensing data and in situ observations. In this paper, we analyze atmospheric, oceanic, and surface changes in the ocean, coast, and land lying near the epicenters of two recent major earthquakes. The changes are studied in terms of the regional fault locations which have been reported by the U.S. Geological Survey as the shake triggering geological structures. Our detailed analyses showed anomalous increases of surface latent heat flux (SLHF) for both the earthquakes. Meaningfully limited to the geographical extents of the regional active faults, the SLHF variation patterns suggest pre-seismic activity 2–3 weeks before the main events. The agreement of these variations with abnormalities in other climatic and surface factors like relative humidity and temperature represents an unusual situation during the same period as well. Spatiotemporal variations of chlorophyll-a was also studied as another earthquake indicator. Abnormal rises in these factors are possibly caused by the formation of micro-cracks, heat production, evaporation, ionization, and upwelling of nutrient-rich water produced by pre-seismic activity prior to the main events.  相似文献   

On persistent primary variables for numerical modeling of gas migration in a nuclear waste repository     

Alain Bourgeat  Mladen Jurak  Farid Smaï 《Computational Geosciences》2013,17(2):287-305

Numerical simulation of gas migration driven by compressible two-phase partially miscible flow in porous media is of major importance for safety assessment of deep geological repositories for long-lived high-level nuclear waste. We present modeling of compositional liquid and gas flow for numerical simulations of hydrogen migration in deep geological radioactive waste repository based on persistent primary variables. Two-phase flow is considered, with incompressible liquid and compressible gas, which includes capillary effects, gas dissolution, and diffusivity. After discussing briefly the existing approaches to deal with phase appearance and disappearance problem, including a persistent set of variables already considered in a previous paper (Bourgeat et al., Comput Geosci 13(1):29–42, 2009), we focus on a new variant of the primary variables: dissolved hydrogen mass concentration and liquid pressure. This choice leads to a unique and consistent formulation in liquid saturated and unsaturated regions, which is well adapted to heterogeneous media. We use this new set of variable for numerical simulations and show computational evidences of its adequacy to simulate gas phase appearance and disappearance in different but typical situations for gas migration in an underground radioactive waste repository.  相似文献   

Deciphering the interaction between quaternary and continental Sabkhas aquifers in Central Tunisia using hydrochemical and isotopic tools   总被引：1，自引：0，他引：1  

Intissar Farid  Rim Trabelsi  Kamel Zouari  Kamel Abid  Mohamed Ayachi 《Environmental Earth Sciences》2013,70(7):3289-3309

Climate aridity and intensive exploitation due to uncontrolled pumping for irrigation have caused a drastic decrease in the piezometric level of the shallow aquifer of Chougafiya plain, central Tunisia, and have seriously degraded groundwater quality. According to the hydrochemical data (Cl^?, SO₄ ^2?, NO₃ ^?, HCO₃ ^?, Br^?, Na⁺, Mg²⁺, K⁺, Ca²⁺, Sr²⁺) and the stable isotopes (¹⁸O and ²H content), groundwater salinization in the investigated aquifer is caused by four main processes: (1) evaporite dissolution (2) cation exchange reactions (3) evaporation processes and (4) mixing with Sabkhas salt water causing salinity to increase in the central and southern parts of the basin. The radiogenic (³H) isotope data provided insight into the presence of significant contemporaneous recharge waters in the western part of the shallow aquifer. The movement of the tritiated water may have occurred according to the general flow path (NW–SE). When tritium was used in conjunction with the stable isotopes and chloride, the mixing process could be clearly identified, especially in the central part of the study area.  相似文献   

Effects of urban wastewater on crab and mollusc assemblages in equatorial and subtropical mangroves of East Africa     

Stefano Cannicci  Fabrizio Bartolini  Farid Dahdouh-Guebas  Sara Fratini  Carlos Litulo  Adriano Macia  Elisha J. Mrabu  Gil Penha-Lopes  Jos Paula 《Estuarine, Coastal and Shelf Science》2009,84(3):305

Mangrove forests are known to accomplish crucial ecosystem functions and services. They are nursery areas for fish, prawns and crabs, which provide coastal communities with a variety of food, timber and chemicals, and protect coasts from catastrophic events, such as tsunamis. Recently, a novel ecological service has been proposed for mangrove systems, namely natural wastewater treatment wetlands. This hypothesis was based on experimental data collected mainly in Chinese mangrove systems, which proved that mangrove soils were efficient in absorbing nutrients. Moreover, sewage loading seemed harmless to both plants and benthic communities in these systems. However, before promoting the use of natural mangroves as pollution buffers, or constructed mangrove wetlands as sewage treatment facilities, more data are needed on their overall tolerance to organic loading. Differences in macrobenthos patterns were thus investigated between peri-urban mangroves and sites not affected by sewage disposal in East Africa. We assessed differences in epifaunal assemblages, comprising crabs and molluscs, employing multivariate ACI unbalanced analyses to compare peri-urban mangrove swamps with those characteristic of non-urban mangroves with similar ecological traits. The sampling design was spatially nested, replicates being assessed at equatorial (southern Kenya) and subtropical (southern Mozambique) sites. The results manifested a consistent increase in crab biomass at the peri-urban sites in both Kenya and Mozambique. Moreover, the peri-urban systems were richer than the non-urban mangroves, both in terms of fiddler crabs (Uca spp.) which feed on benthic microalgae and bacteria, and sesarmids, such as Perisesarma guttatum and Neosarmatium meinerti, which feed on both substratum and leaf litter. The abundance of gastropods, in contrast, decreased significantly, especially in Kenya, mainly due to the disappearance of the mud whelk Terebralia palustris. The results thus indicate that, in East African mangrove systems, domestic wastewater has detectable effects on crabs and molluscs, suggesting their usefulness as bioindicators of its effects in mangroves. Transformed benthic patterns at the peri-urban sites indicated the need for further study of the actual potential of natural mangrove forests to absorb pollution in sewage treatment.  相似文献