scholarly journals Experimental Investigation on the Influence of Oven-Drying on the Geotechnical Properties of Volcanic Ash-Derived Residual Soils

2021 ◽  
Vol 11 (24) ◽  
pp. 11708
Author(s):  
Pablo Eduardo Romero-Mancilla ◽  
José Miguel Montenegro-Cooper ◽  
Robert W. King ◽  
Pablo Lapeña-Mañero ◽  
Carmen García-Casuso
Keyword(s):  
Volcanic Ash ◽  
Geotechnical Properties ◽  
Unit Weight ◽  
Natural State ◽  
Mountain Range ◽  
High Plasticity ◽  
Residual Soils ◽  
Volcanic Origin ◽  
Oven Drying ◽  
Geotechnical Tests

For thousands of years, the volcanic activity present along the Andes Mountain range has generated a large amount of pyroclastic material. As a result, around 60 percent of the soils present in Chile have a volcanic origin, of which, we can find soils derived from volcanic ash. These correspond to soils whose origin is the weathering of volcanic ash, which generates minerals such as allophane, imogolite, and halloysite. The presence of these minerals gives these soils unique geotechnical properties, such as high plasticity, low dry unit weight, and a unique internal structure. Subjecting these soils to extreme temperatures like those needed to perform standard laboratory tests produces changes in their structures, and thus in their geotechnical behavior. These changes are important to be aware of with respect to slope stability problems, embankment conformation, surface foundations, etc. In the present study, a type of soil found in Chile originating from the weathering of volcanic ash and locally named Trumao was studied. Due to its age and formation processes, the main minerals found in the soil are allophane and imogolite, and hence it belongs to the allophanic soil type. The material was studied in its natural state (undisturbed) and, after being oven-dried using common geotechnical tests, the behaviors of both samples were compared. The study shows that some properties are affected significantly by the oven-drying process, and thus it is not recommended to expose the material to high temperatures during geotechnical laboratory testing to avoid misleading results.

scholarly journals Geotechnical and Mineralogical Appraisal of Shale and Claystone Facies of the Maastrichtian Patti Formation, Bida Basin, Nigeria

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Olusola J Ojo ◽  
Oladele A Omotoso ◽  
Adams Agbelekale ◽  
Suraju A Adepoju ◽  
Ayodeji Awe ◽  
...  
Keyword(s):  
Particle Size ◽  
Civil Engineering ◽  
Construction Material ◽  
Liquid Limit ◽  
Geotechnical Properties ◽  
Atterberg Limits ◽  
Minor Amount ◽  
Low Permeability ◽  
High Plasticity ◽  
Swell Potential

The need for construction materials in the rapidly developing areas around Federal Capital Territory, Abuja, Nigeria cannot be overemphasized and this study was undertaken in line with this need. The study area, located about 60km from Abuja, is underlain predominantly by shales and claystones of the Patti Formation. These argillaceous rocks may offer locally sourced construction material if they meet certain specifications, however to date, there has not been a geotechnical study of these rocks. The geotechnical properties and the mineralogy of the shale and claystone were investigated to evaluate their suitability for civil engineering works. Particle size distribution, Atterberg  limits and X-ray diffraction analyses were performed on fifteen shale and claystone samples collected  from  three localities (along an approximately 25km transect) for determination of their geotechnical properties and mineralogical composition. Mineralogical data obtained show the samples are dominated by kaolinite with minor amount of montmorillonite. Quartz and minor amounts of microcline, rutile and anatase dominate the non-clay mineral fraction. Particle size data indicate high proportion of fines and they are well graded. The Atterberg limits indicate that the samples have average values of liquid limit of 51%, plastic limit of 23%, plasticity index of 29% and shrinkage limit of 13%. These indicate they are of medium compressibility, low to medium shrink/swell potential, marginal expansive rating and low permeability. High bulk specific gravity (average of 2.61) suggests the samples are inorganic and this is supported by the consistency limits values. Generally, the results indicate the shale and claystone can be useful as stabilizing materials in civil engineering works. In addition, the marginally expansive nature of the shale and claystone, low permeability and intermediate to high plasticity may make them suitable as road subgrade.Keywords— activity, Bida Basin, Gerinya, Kaolinite, plasticity, Patti Formation

scholarly journals Hidden Hazards: the conditions that potentially enabled the mudflow disaster at Villa Santa Lucía in Chilean Patagonia

2020 ◽  
Author(s):  
Marcelo A. Somos-Valenzuela ◽  
Joaquín E. Oyarzún-Ulloa ◽  
Ivo J. Fustos-Toribio ◽  
Natalia Garrido-Urzua ◽  
Chen Ningsheng
Keyword(s):  
Water Content ◽  
Heat Waves ◽  
Hazard Mapping ◽  
Mountain Range ◽  
Mass Wasting ◽  
Mountain Areas ◽  
Complex Process ◽  
Chilean Patagonia ◽  
Geotechnical Tests ◽  
Steep Slopes

Abstract. The evaluation of potential mass wasting in mountain areas is a very complex process because there is not enough information to quantify the probability and magnitude of these events. Identifying the whole chain of events is not a straightforward task, and the impacts of mass wasting processes depend on the conditions downstream of the origin. Additionally, climate change is playing an essential role in the occurrence and distribution. Mean temperatures are continuously rising to produce long term instabilities, particularly on steep slopes. Extreme precipitations events are more recurrent as well as heat waves that can melt snow and glaciers, increasing the water available to unstabilized slopes. In this paper, we present an example that portraits the complexities in the evaluation of the chain of events. On the 16 of December of 2017, a rockslide occurred in the Yelcho mountain range. In that event, 7 million m3 of rocks and soil fell on the Yelcho glacier depositing 2 million m3 on the glacier terminal, and the rest continued downstream, triggering a mudflow that hit Villa Santa Lucia in the Chilean Patagonia, killing 22 people. The rockslide event or similar was anticipated in the region by the National Geological and Mining Survey (Sernageomin in Spanish). However, the effects of the terrain characteristics along the runout area were more significant than what was anticipated. In this work, we evaluate the conditions that enable the mudflow that hits Villa Santa Lucia. We used the information generated by Sernageomin's professional after the mudflow. We carried out geotechnical tests to characterize the soil. We simulated the mudflow using two hydrodynamics software (r-avaflow and Flo-2D) that can handle the rheology of the water–soil mixture. Our results indicate that the soil is classified as volcanic pumices. This type of soil can be susceptible to the collapse of the structure when subjected to shearing (molding), flowing like a viscous liquid. From the numerical modeling, we concluded that r-avaflow performs better than Flo2D. We can reproduce the mudflow satisfactorily using water content in the mixture ranging from 30 to 40 %. Finally, in order to achieve the water content, we need a source of water smaller than 3 million m3 approximately. From the simulations and soil tests, we determined that in the area scoured by the mudflow, there were around 2 789 500 m3 of water within the soil. Therefore, the conditions of the valley were crucial to enhance the impacts of the landslide. This result is relevant because it highlights the importance of evaluating the complete chain of events to map hazards. We suggest that in future hazard mapping, geotechnical studies in combination with hydrodynamic simulation should be included, in particular, when human lives are at risk.

COMPARISONS OF METHODS OF pH DETERMINATION FOR ORGANIC TERRAIN SURVEYS

1973 ◽  
Vol 53 (2) ◽  
pp. 177-183 ◽  
Author(s):  
W. STANEK
Keyword(s):  
Ph Value ◽  
Liquid Limit ◽  
Natural State ◽  
Confidence Limits ◽  
Practical Application ◽  
Oven Drying ◽  
Ph Values ◽  
Coefficients Of Variation ◽  
The Mean ◽  
A Site

pH values were measured on peat samples taken from a water-logged peatland in Ontario, from April 1970 to April 1971, by 14 procedures: on fresh peat and groundwater, in their natural state; and on combinations of hand-squeezed, air-dried, and oven-dried peat, each rewetted to liquid limit with either distilled H2O, N/100 CaCl2∙2H2O, N/10 KCl, or N/10 CaCl2∙2H2O. Groundwater showed the highest mean pH (4.0), followed by hand-squeezed peat rewetted with distilled H2O (3.8), then fresh peat (3.6). In comparison with fresh peat, air and oven drying lowered the mean pH value by 0.1 and 0.2 units, rewetting with N/100 CaCl2∙2H2O, by 0.4; N/10 KCl, by 0.5; and N/10 CaCl2∙2H2O, by 0.6 units approximately. The coefficients of variation and the confidence limits showed, for practical application, that all methods were equally reliable and that pH determined at any time of the year validly characterized a site.

scholarly journals Numerical simulations of windblown dust over complex terrain: The Fiambalá Basin episode in June 2015

2016 ◽  
Author(s):  
Leonardo A. Mingari ◽  
Estela A. Collini ◽  
Arnau Folch ◽  
Walter Báez ◽  
Emilce Bustos ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Long Range ◽  
Complex Terrain ◽  
Volcanic Ash ◽  
Dust Cloud ◽  
Temporal Distribution ◽  
Dust Particles ◽  
Long Range Transport ◽  
Mountain Range ◽  
Range Transport

Abstract. On the 13 June 2015, the London Volcanic Ash Advisory Centre (VAAC) warned the Buenos Aires VAAC about a possible volcanic eruption from the Nevados Ojos del Salado volcano (6879 m), located in the Andes mountain range on the border between Chile and Argentina. A volcanic ash cloud was detected by the SEVIRI instrument on board the Meteosat Second Generation (MSG) satellites from 14:00 UTC on 13 June. Further studies concluded that the phenomenon was caused by remobilization of ancient pyroclastic deposits (circa 4.5 Ka Cerro Blanco eruption) from the Bolsón de Fiambalá (Fiambalá Basin) in northwestern Argentina. In this paper, we provide the first comprehensive description of the dust episode through observations and numerical simulations. We have investigated the spatio-temporal distribution of aerosols and the emission process over complex terrain to gain insight into the key role played by the orography and the condition that triggered the long-range transport episode. Numerical simulations of windblown dust were performed using the WRF-ARW/FALL3D modeling system with meteorological fields downscaled to a spatial resolution of 2 km in order to resolve the complex orography of the area. Results indicated that favourable conditions to generate dust uplifting occurred in northern Fiambalá Basin, where orographic effects caused strong surface winds. According to short-range numerical simulations, dust particles were confined to near-ground layers around the emission areas. On the other hand, dust aerosols were injected up to 5–6 km high in central and southern regions of the Fiambalá Basin, where intense ascending airflows are driven by horizontal convergence. Long-range transport numerical simulations were also performed to model dust cloud spreading over northern Argentina. Results of simulated vertical particle column mass were compared with the MSG-SEVIRI retrieval product. We tested two numerical schemes: with the default configuration of the FALL3D model, we found difficulties to simulate transport through orographic barriers, whereas an alternative configuration, using a numerical scheme to more accurately compute the horizontal advection in abrupt terrains, substantially improved the model performance.

scholarly journals Volcanic ash as reusable catalyst in the green synthesis of 3H-1,5-benzodiazepines

2019 ◽  
Vol 8 (1) ◽  
pp. 600-610 ◽  
Author(s):  
Mercedes Muñoz ◽  
Gustavo Pasquale ◽  
Angel Gabriel Sathicq ◽  
Gustavo Pablo Romanelli ◽  
Carmen Inés Cabello ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Textural Properties ◽  
Acid Catalyst ◽  
Reusable Catalyst ◽  
Volcanic Complex ◽  
Mountain Range ◽  
Catalytic Materials ◽  
The Andes ◽  
Solvent Free Conditions ◽  
Heterogeneous Acid Catalyst

Abstract The volcanic ash from the Andes mountain range (Puyehue-Cordon Caulle volcanic complex situated in western South America on the Argentinean-Chilean border) was used as heterogeneous acid catalyst in the suitable synthesis of 3H-1,5-benzodiazepines. The natural ashes were classified according to their particle size to generate the different catalytic materials. The catalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), vibrational spectroscopies (FT-IR and Raman), and textural properties were determined by N2 adsorption (SBET). Potentiometric titration with n-butylamine was used to determine the acidic properties of the catalytic materials. Several 3H-1,5-benzodiazepines were obtained by reaction of o-phenylenediamine and substituted 1,3-diphenyl-1,3-propanedione in solvent-free conditions, giving good to excellent yields of a variety benzodiazepines. The method was carried out in environmentally friendly conditions and it was operationally simple. The volcanic ash resulted in a safe and recyclable catalyst.

scholarly journals Mapping the susceptibility of rain-triggered lahars at Vulcano island (Italy) combining field characterization, geotechnical analysis, and numerical modelling

2019 ◽  
Vol 19 (11) ◽  
pp. 2421-2449 ◽  
Author(s):  
Valérie Baumann ◽  
Costanza Bonadonna ◽  
Sabatino Cuomo ◽  
Mariagiovanna Moscariello ◽  
Sebastien Biass ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Slope Angle ◽  
Field Measurements ◽  
Friction Angle ◽  
Unit Weight ◽  
Residual Water ◽  
Probabilistic Modelling ◽  
Cascading Effect ◽  
Geotechnical Tests ◽  
Tephra Fallout

Abstract. The characterization of triggering dynamics and remobilized volumes is crucial to the assessment of associated lahar hazards. We propose an innovative treatment of the cascading effect between tephra fallout and lahar hazards based on probabilistic modelling that also accounts for a detailed description of source sediments. As an example, we have estimated the volumes of tephra fallout deposit that could be remobilized by rainfall-triggered lahars in association with two eruptive scenarios that have characterized the activity of the La Fossa cone (Vulcano, Italy) in the last 1000 years: a long-lasting Vulcanian cycle and a subplinian eruption. The spatial distribution and volume of deposits that could potentially trigger lahars were analysed based on a combination of tephra fallout probabilistic modelling (with TEPHRA2), slope-stability modelling (with TRIGRS), field observations, and geotechnical tests. Model input data were obtained from both geotechnical tests and field measurements (e.g. hydraulic conductivity, friction angle, cohesion, total unit weight of the soil, and saturated and residual water content). TRIGRS simulations show how shallow landsliding is an effective process for eroding pyroclastic deposits on Vulcano. Nonetheless, the remobilized volumes and the deposit thickness threshold for lahar initiation strongly depend on slope angle, rainfall intensity, grain size, friction angle, hydraulic conductivity, and the cohesion of the source deposit.

scholarly journals Distribution of bulk unit weight of residual soils from the Northern Malaysia

2019 ◽  
Vol 1349 ◽  
pp. 012025
Author(s):  
D Jamalludin ◽  
A Ahmad ◽  
Z Zakaria ◽  
M Hashim ◽  
A Ibrahim ◽  
...  
Keyword(s):  
Unit Weight ◽  
Residual Soils

scholarly journals The mudflow disaster at Villa Santa Lucía in Chilean Patagonia: understandings and insights derived from numerical simulation and postevent field surveys

2020 ◽  
Vol 20 (8) ◽  
pp. 2319-2333
Author(s):  
Marcelo A. Somos-Valenzuela ◽  
Joaquín E. Oyarzún-Ulloa ◽  
Ivo J. Fustos-Toribio ◽  
Natalia Garrido-Urzua ◽  
Ningsheng Chen
Keyword(s):  
Hazard Mapping ◽  
Mountain Range ◽  
Mass Wasting ◽  
Mountain Areas ◽  
Hydrodynamic Simulation ◽  
Field Surveys ◽  
Complex Process ◽  
Chilean Patagonia ◽  
Geotechnical Tests ◽  
Better Than

Abstract. The evaluation of potential landslides in mountain areas is a very complex process. Currently, event understanding is scarce due to information limitations. Identifying the whole chain of events is not a straightforward task, and the impacts of mass-wasting processes depend on the conditions downstream of the origin. In this paper, we present an example that illustrates the complexities in the evaluation of the chain of events that may lead to a natural disaster. On 16 December 2017, a landslide occurred in the Yelcho mountain range (southern Chile). In that event, 7 million m3 of rocks and soil fell on the Yelcho glacier, depositing 2 million m3 on the glacier terminal, and the rest continued downstream, triggering a mudflow that hit Villa Santa Lucía in Chilean Patagonia and killing 22 people. The complex event was anticipated in the region by the National Geological and Mining Survey (Sernageomin in Spanish). However, the effects of the terrain characteristics along the run-out area were more significant than anticipated. In this work, we evaluate the conditions that enabled the mudflow that hit Villa Santa Lucía. We used the information generated by Sernageomin's professionals after the mudflow. We carried out geotechnical tests to characterize the soil. We simulated the mudflow using two hydrodynamic programs (r.avaflow and Flo-2D) that can handle the rheology of the water–soil mixture. Our results indicate that the soil is classified as volcanic pumices. This type of soil can be susceptible to the collapse of the structure when subjected to shearing (molding), flowing as a viscous liquid. From the numerical modeling, we concluded that r.avaflow performs better than Flo-2D. The mudflow was satisfactorily simulated using a water content in the mixture ranging from 30 % to 40 %, which would have required a source of about 3 million m3 of water. Coupling the simulations and the soil tests that we performed, we estimated that in the area scoured by the mudflow, there were probably around 2 800 000 m3 of water within the soil. Therefore, the conditions of the valley were crucial to enhancing the impacts of the landslide. This result is relevant because it highlights the importance of evaluating the complete chain of events to map hazards. We suggest that in future hazard mapping, geotechnical studies in combination with hydrodynamic simulation should be included, in particular when human lives are at risk.

scholarly journals Geotechnical Properties of Soft Marine Soil at Chan May Port, Vietnam

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Thi Nu NGUYEN ◽  
Thanh Duong NGUYEN ◽  
Truong Son BUI
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Void Ratio ◽  
Soft Soil ◽  
Field Investigation ◽  
Liquid Limit ◽  
Geotechnical Properties ◽  
Unit Weight ◽  
Dry Unit Weight ◽  
Marine Soil

Soft marine soil deposit is distributed under the sea with many special properties. This type ofsoil is rarely researched in Vietnam because of the difficult geotechnical investigation under the sea level.In this paper, the experimental laboratories were performed to investigate the geotechnical properties ofsoft marine soil at Chan May port, Vietnam. The field investigation results indicate that the thickness ofsoft soil varies from a few meters to more than ten meters. Soft soil has a high value of water content,void ratio, and compressibility and a low value of shear strength. The compression index has a goodrelationship with water content, liquid limit, and dry unit weight. The unit weight, shear strength, and preconsolidationpressure increase with the increase of depth. These results show that the soil in the studyarea is unfavorable for construction activities.

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