scholarly journals From precursory event to climactic caldera formation – variations in water saturation state in the Aso-4 super-eruptive system.

2021 ◽  
Author(s):  
Franziska Keller ◽  
Olivier Bachmann ◽  
Răzvan-Gabriel Popa ◽  
Julien Allaz ◽  
Nobuo Geshi
Keyword(s):  
Water Saturation ◽  
Saturation State ◽  
Caldera Formation

scholarly journals Influence of Humidity on the Elastic Modulus and Axis Compressive Strength of Concrete in a Water Environment

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5696
Author(s):  
Guohui Zhang ◽  
Changbing Li ◽  
Hai Wei ◽  
Mingming Wang ◽  
Zhendong Yang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Water Saturation ◽  
Water Environment ◽  
Systematic Research ◽  
Saturation State ◽  
Soaking Time ◽  
Axial Compressive Strength ◽  
Saturated Concrete ◽  
Compressive Strength Of Concrete

Concrete structures are often in different humidity conditions that have a significant impact on the elastic modulus of concrete, therefore, systematic research on the evolution of the law of concrete elastic modulus under different humidity conditions is needed. In this study, the variation laws of the water saturation of concrete specimens with strength grades C15, C20, and C30 were obtained, and then the influence laws of the water saturation on the concrete axial compressive strength were carried out, and the prediction model of elastic modulus of concrete with respect to water saturation was constructed. The results showed that the water saturation of concrete with strength grades C15, C20, and C30 increased with an extension of immersion time, and the water saturation showed an approximately linear rapid growth within three soaking hours, reaching 47.56%, 71.63%, and 47.29%, respectively. Note, the concrete reached saturation state when the soaking time was 240 h. The axial compressive strength with strength grades C15, C20, and C30 decreased with increased water saturation, and the axial compressive strength of saturated concrete decreased by 27.25%, 21.14%, and 20.76%, respectively, as compared with the dry state concrete. The elastic modulus of concrete with strength grades C15, C20, and C30 increased with increased water saturation, and the elastic modulus of saturated concrete was 1.18, 1.19, and 1.24 times higher than those of dry concrete, respectively.

scholarly journals Influence of the Saturation Ratio on Concrete Behavior under Triaxial Compressive Loading

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Xuan-Dung Vu ◽  
Matthieu Briffaut ◽  
Yann Malecot ◽  
Laurent Daudeville ◽  
Bertrand Ciree
Keyword(s):  
Nuclear Power ◽  
Water Saturation ◽  
Confining Pressure ◽  
Degree Of Saturation ◽  
Triaxial Tests ◽  
Saturation Ratio ◽  
Concrete Wall ◽  
Saturation State ◽  
Massive Concrete ◽  
The Impact

When a concrete structure is subjected to an impact, the material is subjected to high triaxial compressive stresses. Furthermore, the water saturation ratio in massive concrete structures may reach nearly 100% at the core, whereas the material dries quickly on the skin. The impact response of a massive concrete wall may thus depend on the state of water saturation in the material. This paper presents some triaxial tests performed at a maximum confining pressure of 600 MPa on concrete representative of a nuclear power plant containment building. Experimental results show the concrete constitutive behavior and its dependence on the water saturation ratio. It is observed that as the degree of saturation increases, a decrease in the volumetric strains as well as in the shear strength is observed. The coupled PRM constitutive model does not accurately reproduce the response of concrete specimens observed during the test. The differences between experimental and numerical results can be explained by both the influence of the saturation state of concrete and the effect of deviatoric stresses, which are not accurately taken into account. The PRM model was modified in order to improve the numerical prediction of concrete behavior under high stresses at various saturation states.

scholarly journals Geophysical estimation of the damage induced by an observatory digging in a limestone heterogeneous vadose zone – Beauce aquifer (France)

2020 ◽  
Author(s):  
Céline Mallet ◽  
Clara Jodry ◽  
Gautier Laurent ◽  
Mohamed Azaroual
Keyword(s):  
Host Rock ◽  
Water Saturation ◽  
Point Of View ◽  
Time Variability ◽  
Heterogeneous Structure ◽  
Saturation State ◽  
Magnetic Resonance Sounding ◽  
Damaged Zone ◽  
Fractured Limestone ◽  
Initial Zone

<p>The O-ZNS observatory offers a unique geophysical support for characterization, at different scales (from nano- to metric scales) of the heterogeneous Beauce Limestones aquifer. Currently under development at an agricultural site in Villamblain (Centre Val de Loire, France), this observatory is based on an exceptional well (20 m-depth and 4 m-diameter) associated with many external boreholes on an area of around 2 400 m<sup>2</sup>. It will combine different geophysical techniques and innovative multi-geosciences sensors to image, monitor and understand fluid and heat transfers in the heterogeneous structure of the vadoze zone.</p><p>An initial geophysical characterization has been conducted with surface measurements (3D electrical resistivity imaging and 2D Magnetic Resonance Sounding) that gave interesting information on the lithology of O-ZNS site: a silty-clayed soil of a few meter thick, then a highly heterogeneous and karstified limestone and finally, the massive fractured limestone. Cross-hole radar measurements add to these information a description of the initial zone, the soil properties and the water content. Also, data from three boreholes and the collection of core samples as well as logging measurements completed and improved this initial characterization.</p><p>All these data have been used to develop a finite element numerical model representing both the study site and the well under Plaxis 2D. Through the realism of geotechnical engineering including deformation, stability and water flow, the idea, is to anticipate the effect of the digging and provide information about the induced damaged zone that will derive. We also look into describing the evolution of this damaged zone depending on the seasoning variation (i.e. from 3 to 5 m) of the groundwater level. All these characterizations will allow us to better focus our field geophysical investigations on monitoring the damaged zone.</p><p>The model consists of a description of the different soil layers from the boreholes that includes elastic, microstructural and transport properties, followed by a description of the interface between the soil and the well. The hydraulic conditions will take into account the time-variability of fluxes and the aquifer level. Furthermore, this model is coupled with the construction phasing from a civil engineering point of view. The results will give the evolution of stress and strain induced by the engineering development of O-ZNS well in the host rock as well as an estimate of the material displacement and its elasticity limits. The preliminary modelling generated a result stipulating a damaged zone of 1-2 m around the well at the surface. The magnitude of the damaged zone is reduced with depth. It seems that, at the bottom, the host rock is undamaged.</p><p>Undergoing development are focused on refining the model by providing more effective and updated estimations of the soil and structure properties in order to validate or improve the first results together with an estimation of the time evolution of the damaged zone with the water saturation state. Afterward, we will be able to compare and validate these results to pictures and measurements performed during the digging that will start in the spring 2020.</p>

scholarly journals Water saturation effects on elastic wave attenuation in porous rocks with aligned fractures

2014 ◽  
Vol 197 (2) ◽  
pp. 943-947 ◽  
Author(s):  
Kelvin Amalokwu ◽  
Angus I. Best ◽  
Jeremy Sothcott ◽  
Mark Chapman ◽  
Tim Minshull ◽  
...  
Keyword(s):  
Elastic Wave ◽  
Reservoir Characterization ◽  
Wave Attenuation ◽  
Water Saturation ◽  
Theoretical Models ◽  
Ultrasonic Pulse ◽  
Fracture Density ◽  
Porous Rocks ◽  
Saturation State ◽  
Hydrocarbon Reservoir

Abstract Elastic wave attenuation anisotropy in porous rocks with aligned fractures is of interest to seismic remote sensing of the Earth's structure and to hydrocarbon reservoir characterization in particular. We investigated the effect of partial water saturation on attenuation in fractured rocks in the laboratory by conducting ultrasonic pulse-echo measurements on synthetic, silica-cemented, sandstones with aligned penny-shaped voids (fracture density of 0.0298 ± 0.0077), chosen to simulate the effect of natural fractures in the Earth according to theoretical models. Our results show, for the first time, contrasting variations in the attenuation (Q−1) of P and S waves with water saturation in samples with and without fractures. The observed Qs/Qp ratios are indicative of saturation state and the presence or absence of fractures, offering an important new possibility for remote fluid detection and characterization.

scholarly journals Influence of Humidity on the Energy of Specific Strain in the Process of Loading Sedimentary Rocks

2019 ◽  
Vol 41 (4) ◽  
pp. 223-230
Author(s):  
Mirosława Bukowska ◽  
Anna Smolorz
Keyword(s):  
Water Saturation ◽  
Sedimentary Rocks ◽  
Dissipated Energy ◽  
Coal Basin ◽  
Uniaxial Compression Strength ◽  
Mining Operations ◽  
Saturation State ◽  
Upper Silesian Coal Basin ◽  
Specific Strain ◽  
The Given

AbstractThis article presents the results of tests on the energy properties of sedimentary rocks in the Upper Silesian Coal Basin. The rocks were tested both in an air-dry state and in a water saturation state. Samples of sedimentary rocks were collected from boreholes drilled in the underground workings of coal mines located within the area of the city of Jastrzębie, in the areas of the Chwałowice Trough and Rybnik Trough (south-western part of the Upper Silesian Coal Basin) and in the Main Trough. Influence of saturation condition on the values of the tested energy parameters was observed. The values of elastic energy and dissipated energy obtained for the samples tested in water saturation were lower compared to the values obtained for samples tested in air-dry state. As observed, an increase in the values of the given types of specific energy corresponds to an increase in the uniaxial compression strength in air-dry state and in water saturation state. Results of the tests are original and they can be applied while analysing the possibility of the occurrence of some dynamic phenomena and hazards in mine workings in Carboniferous rock mass in the Upper Silesian Coal Basin, caused by mining operations.

Oil Saturation Log Prediction Using Neural Network in New Steamflood Area

2020 ◽  
Author(s):  
A. Syahputra
Keyword(s):  
Neural Network ◽  
Water Saturation ◽  
Prediction Method ◽  
Neural Model ◽  
Training Model ◽  
Acquisition Time ◽  
Oil Saturation ◽  
Full Field ◽  
Remaining Oil ◽  
Observation Wells

Surveillance is very important in managing a steamflood project. On the current surveillance plan, Temperature and steam ID logs are acquired on observation wells at least every year while CO log (oil saturation log or SO log) every 3 years. Based on those surveillance logs, a dynamic full field reservoir model is updated quarterly. Typically, a high depletion rate happens in a new steamflood area as a function of drainage activities and steamflood injection. Due to different acquisition time, there is a possibility of misalignment or information gaps between remaining oil maps (ie: net pay, average oil saturation or hydrocarbon pore thickness map) with steam chest map, for example a case of high remaining oil on high steam saturation interval. The methodology that is used to predict oil saturation log is neural network. In this neural network method, open hole observation wells logs (static reservoir log) such as vshale, porosity, water saturation effective, and pay non pay interval), dynamic reservoir logs as temperature, steam saturation, oil saturation, and acquisition time are used as input. A study case of a new steamflood area with 16 patterns of single reservoir target used 6 active observation wells and 15 complete logs sets (temperature, steam ID, and CO log), 19 incomplete logs sets (only temperature and steam ID) since 2014 to 2019. Those data were divided as follows ~80% of completed log set data for neural network training model and ~20% of completed log set data for testing the model. As the result of neural model testing, R2 is score 0.86 with RMS 5% oil saturation. In this testing step, oil saturation log prediction is compared to actual data. Only minor data that shows different oil saturation value and overall shape of oil saturation logs are match. This neural network model is then used for oil saturation log prediction in 19 incomplete log set. The oil saturation log prediction method can fill the gap of data to better describe the depletion process in a new steamflood area. This method also helps to align steam map and remaining oil to support reservoir management in a steamflood project.

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