Hydrogeotechnical characterization of a metallurgical waste

2006 ◽  
Vol 43 (10) ◽  
pp. 1042-1060 ◽  
Author(s):  
R Rodríguez
Keyword(s):  
Tensile Strength ◽  
Hydraulic Conductivity ◽  
Cyclic Load ◽  
Water Pressure ◽  
Degree Of Saturation ◽  
Water Retention Curve ◽  
Triaxial Tests ◽  
Drying Process ◽  
Metallurgical Waste

This paper presents the results of hydrogeotechnical characterization tests carried out on the metallurgical waste (MW) from a tailings impoundment located on the terraces of the Moa River, Cuba. Characterization of the MW includes chemical and mineralogical analysis, oedometer tests, triaxial tests, tensile strength tests, determination of the water retention curve, and shrinkage and permeability tests. The MW, which has a grain-size distribution similar to that of a silt, mainly contains iron and heavy metals minerals and has low plasticity. Consolidated undrained triaxial tests on remoulded samples indicate a dilative behaviour, with a decrease in pore-water pressure near failure. The material is susceptible to liquefaction when subjected to a cyclic load in the triaxial test. Hydraulic conductivity, soil stiffness, and compressive and tensile strength of the MW have an important dependence on the degree of saturation and vary significantly during the drying process. The results indicate that, during the drying process, cracks in the MW initiate in quasi-saturated conditions. The cracks increase the hydraulic conductivity by more than one order of magnitude compared with that of intact samples of MW. The main environmental risk with this MW is the possibility of liquefaction under a cyclic load due to an earthquake and the increase in saturated hydraulic conductivity due to desiccation cracks.Key words: desiccation cracks, hydrogeotechnical properties, liquefaction, metallurgical waste, characterization.

Mitigation of liquefaction triggering due to bio-gas-induced desaturation using element tests and the strain energy approach

2021 ◽  
pp. 875529302110416
Author(s):  
Mohammad Hassan Baziar ◽  
Omid Eslami Amirabadi
Keyword(s):  
Pore Water ◽  
Strain Energy ◽  
Water Pressure ◽  
Gas Bubbles ◽  
Energy Approach ◽  
Degree Of Saturation ◽  
Ammonium Ion ◽  
Triaxial Tests ◽  
Treated Sample ◽  
Urease Enzyme

Currently, conventional remediation of liquefaction triggering may have many environmental effects, and this important issue has led researchers to look for more sustainable methods. In this research, one of the new bio-improvement methods (biogas) has been used to generate gas bubbles within a soil, susceptible to liquefaction. Using this method, two bio materials create ammonium ions and carbonate, in which ammonium ion is converted into nitrate due to the presence of bacteria in water, and they are eventually converted to nitrogen gas in an anaerobic condition. The nitrogen bubbles created in water reduce the soil’s degree of saturation, which in effect increases the soil’s resistance to liquefaction occurrence. In this study, two sources of urease enzyme were used to reduce the soil degree of saturation. The effects of various parameters, including the optimum concentration of each substance for optimum time to generate gas bubbles, as well as the effect of the oxygen amount in water were investigated using monotonic triaxial tests. The results illustrated that the addition of the mentioned two substances to the oxab (water with 60 ppm oxygen) or tap water decreased the pore water pressure due to desaturation. Finally, the energy approach was used to test the substance containing the amount of oxab with the highest decrease in pore water generation, here called “optimum selection,” in the cyclic triaxial device, and the results were analyzed to evaluate liquefaction occurrence. The outcome of these results revealed that compared with the strain energy of the non-treated sample, the treated sample had a much higher strain energy; in other words, the treated sample needed a larger amount of loading to trigger liquefaction.

scholarly journals Simultaneous Determination of Water Retention Curve and Unsaturated Hydraulic Conductivity of Substrates Using a Steady-state Laboratory Method

HortScience ◽  
2010 ◽  
Vol 45 (7) ◽  
pp. 1106-1112 ◽  
Author(s):  
Paraskevi A. Londra
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Hydraulic Conductivity ◽  
Water Retention ◽  
Water Pressure ◽  
Pressure Head ◽  
Laboratory Method ◽  
Water Retention Curve ◽  
Retention Curve ◽  
Unsaturated Hydraulic Conductivity

For effective irrigation and fertilization management, the knowledge of substrate hydraulic properties is essential. In this study, a steady-state laboratory method was used to determine simultaneously the water retention curve, θ(h), and unsaturated hydraulic conductivity as a function of volumetric water content, K(θ), and water pressure head, K(h), of five substrates used widely in horticulture. The substrates examined were pure peat, 75/25 peat/perlite, 50/50 peat/perlite, 50/50 coir/perlite, and pure perlite. The experimental retention curve results showed that in the case of peat and its mixtures with perlite, there is a hysteresis between drying and wetting branches of the retention curve. Whereas in the case of coir/perlite and perlite, the phenomenon of hysteresis was less pronounced. The increase of perlite proportion in the peat/perlite mixtures led to a decrease of total porosity and water-holding capacity and an increase of air space. Study of the K(θ) and K(h) experimental data showed that the hysteresis phenomenon of K(θ) was negligible compared with the K(h) data for all substrates examined. Within a narrow range of water pressure head (0 to –70 cm H2O) that occurs between two successive irrigations, a sharp decrease of the unsaturated hydraulic conductivity was observed. The comparison of the K(θ) experimental data between the peat-based substrate mixtures and the coir-based substrate mixture showed that for water contents lower than 0.40 m3·m−3, the hydraulic conductivity of the 50/50 coir/perlite mixture was greater. The comparison between experimental water retention curves and predictions using Brooks-Corey and van Genuchten models showed a high correlation (0.992 ≤ R2 ≤ 1) for both models for all substrates examined. On the other hand, in the case of unsaturated hydraulic conductivity, the comparison showed a relatively good correlation (0.951 ≤ R2 ≤ 0.981) for the van Genuchten-Mualem model for all substrates used except perlite and a significant deviation (0.436 ≤ R2 ≤ 0.872) for the Brooks-Corey model for all substrates used.

scholarly journals Determining hydraulic properties of concrete and mortar by inverse modelling

2012 ◽  
Vol 1475 ◽  
Author(s):  
Sébastien Schneider ◽  
Dirk Mallants ◽  
Diederik Jacques
Keyword(s):  
Hydraulic Conductivity ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Inverse Modelling ◽  
Degree Of Saturation ◽  
Water Retention Curve ◽  
Retention Data ◽  
Capillary Suction ◽  
Near Surface ◽  
Van Genuchten Model

ABSTRACTThis paper presents a methodology and results on estimating hydraulic properties of the concrete and mortar considered for the near surface disposal facility in Dessel, Belgium, currently in development by ONDRAF/NIRAS. In a first part, we estimated the van parameters for the water retention curve for concrete and mortar obtained by calibration (i.e. inverse modelling) of the van Genuchten model [1] to experimental water retention data [2]. Data consisted of the degree of saturation measured at different values of relative humidity. In the second part, water retention data and data from a capillary suction experiment on concrete and mortar cores was used jointly to successfully determine the van Genuchten retention parameters and the Mualem hydraulic conductivity parameters (including saturated hydraulic conductivity) by inverse modelling.

scholarly journals Microfabricated sol-gel relative humidity sensors for soil suction measurement during laboratory tests

2017 ◽  
Vol 54 (8) ◽  
pp. 1176-1183 ◽  
Author(s):  
Rafaela Cardoso ◽  
Gabriele Sarapajevaite ◽  
Oleksandr Korsun ◽  
Susana Cardoso ◽  
Laura Ilharco
Keyword(s):  
Relative Humidity ◽  
Unsaturated Soils ◽  
Laboratory Tests ◽  
Sol Gel ◽  
Degree Of Saturation ◽  
Water Retention Curve ◽  
Retention Curve ◽  
Calibration Protocol ◽  
Scientific Potential

Currently there are no small sensors that can be incorporated inside soil samples for laboratory testing, to monitor water transport during loading. This is an important limitation to a better understanding of the hydromechanical coupled behaviour of soils. A sol-gel relative humidity sensor (11 mm × 11 mm), microfabricated in a clean room environment, was conceived to be incorporated in soil specimens during standard laboratory tests. The sensor operates based on changes in electrical resistivity detected by a cerium-doped silica–titania film deposited using a sol-gel technique over interdigitated aluminium electrodes spaced at 300 μm. To the best of the authors’ knowledge, sol-gel sensors for relative humidity measurement have never been used in soils; therefore, this is a novel application. The water retention curve of compacted kaolin was measured with the sensors and compared with the curve found using water dewpoint potentiometer WP4-C. The sensors were also tested incorporated in an oedometer cell, in which load was applied under vapour equilibrium. It was possible to detect the increment of the degree of saturation during compression. The use of the developed sensors incorporated in soils is considered acceptable for suction ranges between 1 and 10 MPa, which extends the suction interval covered by tensiometers, normally operating up to 2 MPa. Although the sensors require improvements in terms of sol-gel deposition and calibration protocol, the results confirm their scientific potential for being used in testing and characterization of unsaturated soils.

scholarly journals Changes on diametral compression behaviour of compacted marls due to drying

2020 ◽  
Vol 195 ◽  
pp. 03008
Author(s):  
Carmen Covadonga Garcia-Fernandez ◽  
Rafaela Cardoso ◽  
Martina Inmaculada Alvarez-Fernandez ◽  
Celestino Gonzalez-Nicieza
Keyword(s):  
Tensile Strength ◽  
Water Content ◽  
Degree Of Saturation ◽  
Water Retention Curve ◽  
Tensile Behaviour ◽  
Compression Tests ◽  
Diametral Compression ◽  
Earth Structures ◽  
Influence Of Water ◽  
Brazilian Splitting

Cracking due to desiccation can compromise the behaviour of earth structures built with compacted clayey soils by promoting water access and consequent volume changes on further wetting. Tensile strength therefore is important to be considered when studying the behaviour of such structures, and in particular its dependence on the degree of saturation or water content. The influence of water content in tensile behaviour of compacted marls was investigated by performing diametral compression tests (Brazilian splitting tests), where axial deformations were measured besides strength. The samples were prepared by compaction at optimum point using standard compaction energy (optimum water content 16%) and then dried by vapour equilibrium to reach water contents between 5% and 16%. The correspondence between water content and suction was done by using the drying branch of the water retention curve, measured using WP4 equipment (Water Dewpoint Potentiometer). Good relationships were found between tensile strength and the water content (and suction). In addition, the study was completed with the analysis of other parameters such as the semi-contact angle created in the loaded area and the stiffness of the material, which also showed changes with water content.

scholarly journals CARACTERIZAÇÃO FÍSICO-HÍDRICA DE UM CONDICIONADOR DE SOLO E SEUS EFEITOS QUANDO MISTURADO A UM SUBSTRATO ORGÂNICO

Irriga ◽  
2004 ◽  
Vol 9 (2) ◽  
pp. 94-105 ◽  
Author(s):  
Eliezer Santurbano Gervásio ◽  
José Antônio Frizzone
Keyword(s):  
Hydraulic Conductivity ◽  
Laboratory Tests ◽  
Water Retention ◽  
Saline Solution ◽  
Organic Substrate ◽  
Water Retention Curve ◽  
Distilled Water ◽  
Retention Curve ◽  
Soil Conditioner

CARACTERIZAÇÃO FÍSICO-HÍDRICA DE UM CONDICIONADOR DE SOLO E SEUS EFEITOS QUANDO MISTURADO A UM SUBSTRATO ORGÂNICO  Eliezer Santurbano Gervásio1;  José Antônio Frizzone21Instituto Centro de Ensino Tecnológico, Unidade Descentralizada de Sobral, Sobral, CE, [email protected] de Engenharia Rural, Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba, SP.  1 RESUMO              O propósito desse trabalho foi caracterizar as propriedades físico-hídricas de um condicionador de solo e verificar os seus efeitos quando misturado a um substrato orgânico. Foi utilizado o condicionador comercial TerraCottem®, o qual foi submetido a ensaios de absorção em água destilada, absorção em solução salina e reabsorção. Posteriormente, doses do condicionador (0; 2,5; 5; 7,5 e 10kg m-3) foram adicionadas a um substrato orgânico, o qual foi submetido a ensaios laboratoriais para a determinação da curva característica de retenção de água e condutividade hidráulica do substrato saturado. Os excelentes resultados obtidos em laboratório, principalmente em termos de absorção e reabsorção, não são os mesmos quando da utilização do condicionador misturado ao substrato, podendo inviabilizar a sua aplicação principalmente devido o seu elevado custo. Quando o objetivo é a retenção de água, a atividade dos polímeros hidroabsorventes fica reduzida quando adicionados ao substrato orgânico.  UNITERMOS: Condicionador, polímeros hidroabsorventes, substrato.  GERVÁSIO, E. S.; FRIZZONE, J. A. PHYSICO-HYDRIC CHARACTERIZATION OF A SOIL CONDITIONER AND ITS EFFECTS WHEN MIXED TO AN ORGANIC SUBSTRATE  2 ABSTRACT  The purpose of this work was to characterize the physico-hydric properties of a soil conditioner and verify its effects when mixed to an organic substrate. Commercial conditioner TerraCottem® was used, then submitted to absorption tests in distilled water, in saline solution and re-absorption. Afterwards, doses of the conditioner (0; 2.5; 5; 7.5 and 10kg m-3) were added to an organic substrate, which was submitted to laboratory tests to determine the characteristic water retention curve and hydraulic conductivity of the saturated substrate. The excellent results obtained in laboratory, mainly for absorption and re-absorption, are not the same ones when compared to the use of the conditioner mixed to an organic substrate, which might make its application impossible mainly due to its high cost. When the objective is water retention, the activity of hydro absorbent polymers is reduced if they are added to organic substrate.  KEYWORDS: Conditioner, hydro absorbent polymers, substrate

Preliminary Structural Design of OCAES Vessel

2014 ◽  
Author(s):  
Jinfu Xiao ◽  
M. Gabr ◽  
M. S. Rahman
Keyword(s):  
Cyclic Load ◽  
Material Selection ◽  
Water Pressure ◽  
Air Pressure ◽  
Compressed Air ◽  
Deformation Pattern ◽  
Additional Advantage ◽  
Large Water ◽  
Rectangular Configuration

A vessel for Offshore Compressed Air Energy Storage (OCAES) is being considered as a part of the emerging technology to store intermittently generated energy from offshore renewable sources. The basic idea is to submerge the storage vessel into the ocean at a large water depth, convert the energy into compressed air, store it with using the hydrostatic water pressure to balance the compressed air pressure without requiring the storage vessels to resist high internal air pressure. An additional advantage is that the interface of air and water acts as a piston to maintain the air pressure level. In this study, a rectangular configuration and a cylindrical configuration are proposed for the OCEAS vessel. Stress controlled analyses are performed for the preliminary design of the OCAES vessel with emphasis on characterization of applied cyclic load induced by the air/water exchange in the inflation/deflation process. The stress distribution and deformation pattern in the OCAES vessel at different loading stages are studied by using the multi-physics FEM program COMSOL. Key parameters including storage volume, geometry of OCAES vessel, and material selection are discussed.

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