Effect of decompression and suction on macroscopic and microscopic behavior of a clay rock     

Xin Wei  Myriam Duc  Mahdia Hattab  Thierry Reuschlé  Said Taibi  Jean-Marie Fleureau 《Acta Geotechnica》2017,12(1):47-65

The goal in this research was to analyze the effects of decompression and suction on the formation of cracks in a clay rock from the Andra (French National Radioactive Waste Management Agency) site at Bure (Meuse–Haute-Marne, France). The article investigates the relationship between the changes in the hydromechanical properties and the changes in microstructure and porosity. Concerning the effect of decompression, at the macroscopic scale, the study highlighted an important effect on the elastic modulus and permeability, but little effect at the microscopic scale except an evolution of mineralogy related to the oxidation of pyrite often present in layers where cracks develop. Concerning the effect of suction, at the macroscopic level, the results showed that, on drying path, the change in the properties of the material was very small, whereas, on wetting path, a large decrease in tensile strength and gas permeability was observed. At the microscopic level, observations with SEM and ESEM, and measurements with MIP, highlighted the evolution of microstructural organization as a function of suction, and the propagation and enlargement of cracks on wetting path, rather than on drying path.  相似文献   

Identification and mapping of clay minerals in the region of Djebel Meni (Northwestern Algeria) using hyperspectral imaging,EO-1 Hyperion sensor     

Lyes Zazi  Abdelhak Boutaleb  Mohamed Said Guettouche 《Arabian Journal of Geosciences》2017,10(11):252

Applied in Djebel Meni (Northwestern of Algeria), this research highlights the results obtained from the supervised classification using the Spectral Angle Mapper (SAM) algorithm, through introducing the spectral signatures of illite, kaolinite, and montmorillonite, via Jet Propulsion Laboratory (JPL) spectral library. These results were compared to the ones of the SAM classification, which use spectral signatures obtained by the Sequential Maximum Angle Convex Cone (SMACC) endmembers extraction algorithm. This implies the ability to detect and identify any object present on the Earth’s surface, whether its nature is mineral, vegetal, or human made, from hyperspectral imaging. By extracting the spectral signatures with the SMACC algorithm and matching them to the current signatures of JPL spectral library, comparing spectral signatures with another is not an easy task. Indeed, for a better comparison and a more appropriate interpretation in the use of the SAM classification, the results obtained were very relatively convincing because, regarding very strong similarities. It appears also that the signatures extracted with SMACC occupy the same areas as those of the JPL spectral library. This method of detection and identification of any present object on the Earth’s surface is rather conclusive.  相似文献   

Current Status of Marine Pollution and Mitigation Strategies in Arid Region: A Detailed Review     

Chitrakar  Prerana  Baawain  Mahad Said  Sana  Ahmad  Al-Mamun  Abdullah 《Ocean Science Journal》2019,54(3):317-348

Ocean Science Journal - Coastal pollution is becoming a significant threat for both marine ecosystems and humans. Marine pollution and coastal degradation are severely exacerbated by anthropogenic...  相似文献   

Nagmati River Sub-watershed Prioritization Using PCA,Integrated PCWS,and AHP: A Case Study     

Siddiqui  Rabab  Said  Saif  Shakeel  Mohammad 《Natural Resources Research》2020,29(4):2411-2430

Prioritization of potential regions that are severely threatened by soil erosion is a prerequisite for formulating and implementing conservation measures and management practices, particularly in fragile semiarid regions. The present study prioritized eight delineated Nagmati sub-watersheds located in the Kutch District of Gujarat State, India, based on three approaches, namely principal component analysis (PCA), integrated PCA with weighted sum (I-PCWS), and analytical hierarchy process (AHP), and on 10 morphometric erosion risk parameters (ERPs). Sub-watersheds were categorized into three priority classes, namely high, medium, and low. PCA retrieved the three most significant ERPs (i.e., length of overland flow, Lo; drainage texture, Dt; and compactness coefficient, Cc) explaining 86.876% of the variance and exhibiting the highest correlation, i.e., r?=?0.961, 0.986, and 0.934 for the first three principal components. Sub-watersheds SW2 and SW7 were rated high priority, SW1 was rated low priority, and the rest were rated medium priority. The I-PCWS approach revealed that sub-watersheds SW2, SW6, and SW7 were in high-priority zone, followed by SW3, SW4, and SW8 in medium-priority zone and SW1 and SW5 in the low-priority zone. The AHP assigned the highest and lowest ranks to “Lo” and “Cc,” respectively, with consistency ratio of 8.1% and principal eigenvalue of 11.075. Results from AHP revealed sub-watershed SW2 to be the highest priority and sub-watersheds SW1 and SW5 to be the lowest priority. Out of eight prioritized sub-watersheds from three approaches, five were found to be the common priority classes, with SW2, SW6, and SW7 demanding urgent implementation of efficient soil conservation measures to prevent further degradation of the identified regions. Results from I-PCWS approach closely complied with the existing landforms within the study area, and this approach was considered more reliable and robust than the other two approaches. The methodology adopted in this study can be applied to different vulnerable, data-scarce regions to sustainably manage and conserve soil erosion through efficiently framed strategies.

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Enhancement of infiltration rate of clogged porous beds in the vicinity of dams in arid zones by the roots of indigenous Ziziphus spina-christ trees     

Ali Al-Maktoumi  Anvar Kacimov  Hamed Al-Busaidi  Said Al-Ismaily  Ahmed Al-Mayahi  Salim Al-Khanbashi  Abdulla Al-Sulaimi 《水文研究》2020,34(22):4226-4238

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An Overview of the Use of Rockbolts as Support Tools in Mining Operations     

Peter  Kolapo  Moshood  Onifade  Akinseye  Praise Oluwatomisin  Martha  Amwaama  Khadija  Said Omar  Abdulsalam  Jibril  Ismail  Lawal Abiodun  Emman  Aladejare Adeyemi 《Geotechnical and Geological Engineering》2022,40(4):1637-1661

Geotechnical and Geological Engineering - Historically, the idea of designing and installing rockbolts in rockmasses can be traced back to the construction of the Snowy Mountain hydroelectric...  相似文献   

Extreme positive Ce-anomalies in a 3.0 Ga submarine volcanic sequence,Murchison Province: Oxygenated marine bottom waters     

Robert Kerrich  Nuru Said 《Chemical Geology》2011,280(1-2):232-241

Systematic positive anomalies of Ce, where Ce/Ce* spans 2.1 to 11.4, are present in basalts and rhyolites of a 2.96 Ga submarine volcanic sequence of the Murchison Province, Western Australia. This volcanic sequence is host to a stratabound Cu–Zn deposit that formed on the seafloor from a seawater hydrothermal system. These are true Ce anomalies as Pr/Pr* < 1. In modern oxygenated marine water Ce is sequestered by Mn-oxides and hydroxides, which coprecipitate with Fe-oxides and hydroxides as nodules and crusts on the ocean floor, as well as Fe–Mn chemical sediments from hydrothermal systems at ocean spreading centers. Fe–Mn sediments have positive Ce anomalies and marine water complementary negative anomalies. Such Ce anomalies have not formerly been reported for Archean hydrothermally altered volcanic rocks. These extreme anomalies are attributed to Mn-transport in shallow-circulating oxygenated marine bottom waters peripheral to the deeper, hotter, hydrothermal system from which the Cu–Zn deposit formed, and record an oxygenated marine environment ~ 500 Ma before the so-called great oxidation event at ~ 2.4 Ga. Results for positive Ce anomalies in the Golden Grove volcanic sequence are complementary to negative anomalies in Archean BIF, collectively stemming from particulate scavenging of Ce^+ 3 in an oxic water column.  相似文献   

Heterogeneities characterization from velocity logs using multifractional Brownian motion     

Said Gaci  Naima Zaourar 《Arabian Journal of Geosciences》2011,4(3-4):535-541

Well logs provide additional information from the borehole that cannot be derived from other subsurface investigations. Their analysis may bring supplementary features about the earth’s heterogeneities. In previous researches, the logs were modeled using fractional Brownian motions indexed by Hurst (or Hölder) exponents quantifying their global regularity degrees. Indeed, these monofractal models, characterized by the same Hurst exponent, do not allow to study the depth-evolution of the local Hurst parameter. In order to overcome this problem, we propose to model the logs using multifractional Brownian motions and suggest an algorithm, developed previously for financial time series, to estimate the local Hurst exponent function. First, the potential of this algorithm is assessed through its application on synthetic sonic log data simulated by the successive random additions method. We note that the estimated Hurst functions (or regularity profiles) are very close to the theoretical Hurst functions. Second, this analysis is extended to sonic logs data from the KTB pilot borehole (Germany). Using the resulted regularity profiles, we carry out a lithological segmentation and fault identification on the geological layers crossed by the well. We derived also a correlation between the Hurst value variation and the lithological changes.  相似文献   

The Effect of pH on Electro-osmotic Flow in Argillaceous Rocks     

Mohamed Younes Ahmed  Said Taibi  Hanène Souli  Jean-Marie Fleureau 《Geotechnical and Geological Engineering》2013,31(4):1335-1348

The use of electro-osmosis in geotechnical engineering has been considered since 1930. Its application has been tested in several sectors like the fight against rising damp in porous materials, the consolidation of soils as well as the remediation of the soils contaminated by oil and heavy metals, etc. The paper presents an experimental study of the electrokinetic phenomena resulting from the application of an electric field to argillaceous sandstones. The electroosmotic tests required the development of a completely new experimental device composed of a confining cell, of a system of measurement and control of the pH of the electrolyte near the electrodes, of a system of control and measurement of the voltage and current at the edges of the sample, and of a system of measurement of inlet (anodic) and outlet (cathodic) flows. Various boundary conditions are considered with and without control of pH. In addition, a micro structural modelling of the electrokinetic phenomena makes it possible to quantify the electro osmotic conductivity with a good agreement with experiments.  相似文献   

A thermo‐hydro‐mechanical model for unsaturated soils based on the effective stress concept     

Matthieu Dumont  Said Taibi  Jean‐Marie Fleureau  Nabil Abou‐Bekr  Abdelghani Saouab 《国际地质力学数值与分析法杂志》2011,35(12):1299-1317

A simple thermo‐hydro‐mechanical (THM) constitutive model for unsaturated soils is described. The effective stress concept is extended to unsaturated soils with the introduction of a capillary stress. This capillary stress is based on a microstructural model and calculated from attraction forces due to water menisci. The effect of desaturation and the thermal softening phenomenon are modelled with a minimal number of material parameters and based on existing models. THM process is qualitatively and quantitatively modelled by using experimental data and previous work to show the application of the model, including a drying path under mechanical stress with transition between saturated and unsaturated states, a heating path under constant suction and a deviatoric path with imposed suction and temperature. The results show that the present model can simulate the THM behaviour in unsaturated soils in a satisfactory way. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献