scholarly journals Response of Transitional Mixtures Retaining Memory of In-Situ Overburden Pressure Monitored Using Electromagnetic and Piezo Crystal Sensors

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2570
Author(s):  
Sang Yeob Kim ◽  
Jong-Sub Lee ◽  
Junghee Park
Keyword(s):  
Shear Wave ◽  
Shear Wave Velocity ◽  
Classification System ◽  
Critical Role ◽  
Soil Classification ◽  
Engineering Properties ◽  
Overburden Pressure ◽  
Low Threshold

The major and minor components in granular soil materials determine their properties and behavior. This study explores the transitional behavior within threshold fines fraction of soil mixtures based on the data from the literature and experiments. From the literature survey, the void ratio, shear wave velocity, compression index, and friction angle capture the transitional turning point between the low and data-adjusted high threshold fines fractions. In particular, there is a dramatic change in hydraulic conductivity below the low threshold fines fraction that highlights the critical role of small amounts of fines in the fluid flow (e.g., clogging). From an experimental study, the engineering properties of natural soil samples identified using deformation and elastic wave sensors show transitional trends within the Revised Soil Classification System framework. The evolution of compressibility and shear wave velocity indicate that either coarse, fine, or both particles are likely to contribute to large and small strain stiffnesses when the effective stress is below 400 kPa. Thereafter, both engineering properties indicate that the soil sample retains a memory of in-situ overburden pressure when the effective stress is around 400 kPa. There is a critical role of fines that are slightly higher than low threshold fines fraction on engineering properties that promote the application of Revised Soil Classification System RSCS to natural soils.

scholarly journals CHARACTERIZING A TROPICAL SOIL VIA SEISMIC IN SITU TESTS

2019 ◽  
Vol 37 (3) ◽  
pp. 263
Author(s):  
Breno Padovezi Rocha ◽  
Heraldo Luiz Giacheti
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Soil Profile ◽  
Site Investigation ◽  
Tropical Soil ◽  
Engineering Properties ◽  
Foundation Engineering

ABSTRACT. The shear wave velocity (Vs) is an important geotechnical parameter to be used in dynamic problems (e.g. earthquakes and vibration problems) as well as in static deformation analysis such as excavations and foundation engineering design. There are several in situ seismic tests to determine Vs such as the crosshole and the downhole techniques, as well as hybrid tests (e.g. seismic dilatometer – SDMT). This paper presents crosshole, downhole and SDMT tests carried out in a typical tropical soil profile from Brazil. Advantages and limitations regarding the test procedures and interpretation are briefly presented and differences observed among Vs determined by these techniques are discussed. Shear wave velocities (Vs) estimated from the crosshole, downhole and SDMT tests ranging from 194 to 370 m/s. The shear wave velocity suggests that the experimental site could be divided into two strata, which are in agreement with soil profile description. The maximum shear modulus (G0) calculated from the Vs by theory of elasticity can be used to show the investigated tropical soil is a typical unusual geomaterial. This article also emphasizes that the SDMT is a useful test for site investigation since it allows a great means for profiling geostratigraphy and soil engineering properties during routine site investigation as well as for dynamics problems. Keywords: shear wave velocity, maximum shear modulus, crosshole, downhole, SDMT.RESUMO. A velocidade de onda cisalhante (Vs) é um parâmetro geotécnico empregado em análises dinâmicas (terremotos e problemas de vibração), bem como em análises estáticas (escavações e projeto de fundações). Existem vários ensaios sísmicos de campo para a determinação de Vs, entre eles as técnicas crosshole e downhole, e os ensaios híbridos (por exemplo, dilatômetro sísmico – SDMT). Este artigo apresenta os ensaios crosshole, downhole e SDMT realizados em um perfil típico de solo tropical do Brasil, as vantagens e limitações dos procedimentos de ensaio e de interpretação são brevemente apresentadas, e as diferenças observadas entre os valores de Vs determinados pelas diferentes técnicas são discutidas. Os perfis de Vs determinados pelas diferentes técnicas variaram de 194 a 370 m/s. A velocidade da onda cisalhante sugere que o campo experimental investigado pode ser dividido em dois horizontes, os quais estão de acordo com a descrição do perfil do solo estudado. O módulo de cisalhamento máximo (G0), calculado a partir de Vs pela teoria da elasticidade, pode ser utilizado para demonstrar o comportamento não convencional do solo investigado. Este artigo também enfatiza que o SDMT é um ensaio geotécnico útil para a investigação geotécnica do subsolo, uma vez que permite a definição do perfil estratigráfico e a estimativa de parâmetros estáticos e dinâmicos de um projeto.Palavras-chave: velocidade de onda cisalhante, módulo de cisalhamento máximo, crosshole, downhole, SDMT.

Molecular modulation of calcium oxalate crystallization

2006 ◽  
Vol 291 (6) ◽  
pp. F1123-F1132 ◽  
Author(s):  
James J. De Yoreo ◽  
S. Roger Qiu ◽  
John R. Hoyer
Keyword(s):  
Molecular Modeling ◽  
Calcium Oxalate ◽  
Stone Formation ◽  
Energy Levels ◽  
Critical Role ◽  
Specific Interactions ◽  
Crystal Surfaces ◽  
Site Specific

Calcium oxalate monohydrate (COM) is the primary constituent of the majority of renal stones. Osteopontin (OPN), an aspartic acid-rich urinary protein, and citrate, a much smaller molecule, are potent inhibitors of COM crystallization at levels present in normal urine. Current concepts of the role of site-specific interactions in crystallization derived from studies of biomineralization are reviewed to provide a context for understanding modulation of COM growth at a molecular level. Results from in situ atomic force microscopy (AFM) analyses of the effects of citrate and OPN on growth verified the critical role of site-specific interactions between these growth modulators and individual steps on COM crystal surfaces. Molecular modeling investigations of interactions of citrate with steps and faces on COM crystal surfaces provided links between the stereochemistry of interaction and the binding energy levels that underlie mechanisms of growth modification and changes in overall crystal morphology. The combination of in situ AFM and molecular modeling provides new knowledge that will aid rationale design of therapeutic agents for inhibition of stone formation.

Soil Liquefaction Evaluation of Offshore Site Based on In Situ Shear Wave Velocity Measurements

2013 ◽  
Vol 405-408 ◽  
pp. 470-473
Author(s):  
Sheng Jie Di ◽  
Ming Yuan Wang ◽  
Zhi Gang Shan ◽  
Hai Bo Jia
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Wind Farm ◽  
Soil Liquefaction ◽  
Offshore Wind ◽  
Velocity Measurements ◽  
Liquefaction Resistance ◽  
Liquefaction Potential

A procedure for evaluating liquefaction resistance of soils based on the shear wave velocity measurements is outlined in the paper. The procedure follows the general formal of the Seed-Idriss simplified procedure. In addition, it was developed following suggestions from industry, researchers, and practitioners. The procedure correctly predicts moderate to high liquefaction potential for over 95% of the liquefaction case histories. The case study for the site of offshore wind farm in Jiangsu province is provided to illustrate the application of the proposed procedure. The feature of the soils and the shear wave velocity in-situ tested in site are discussed and the liquefaction potential of the layer is evaluated. The application shows that the layers of the non-cohesive soils in the depths 3-11m may be liquefiable according to the procedure.

scholarly journals Role of pressure solution in the formation of bedding-parallel calcite veins in an immature shale (Cretaceous, southern UK)

2018 ◽  
Vol 156 (5) ◽  
pp. 918-934 ◽  
Author(s):  
QINGFENG MENG ◽  
JOHN HOOKER ◽  
JOE CARTWRIGHT
Keyword(s):  
Critical Role ◽  
Maximum Principal Stress ◽  
Feedback Mechanism ◽  
Black Shales ◽  
Pressure Solution ◽  
Overburden Pressure ◽  
Axis Orientation ◽  
Calcite Veins ◽  
Fibre Growth

AbstractBedding-parallel fibrous calcite veins in black shales (Cretaceous, southern UK) were investigated using a combined field, stable isotopic geochemistry, petrographic and crystallographic method to examine their formation mechanism. Calcite veins occur in all shale beds and are most abundant in the bituminous shales of the Chief Beef Beds. The calcite fibres in these veins exhibit either an antitaxial fibre growth with curvy stylolites as the median zone, or a predominantly syntaxial, upwards growth. The calcite veins range from –0.49 to 1.78‰ of δ13C values, and –6.53 to –0.03‰ of δ18O values, which are both similar to those of their host shales. Our petrographic observations demonstrate that subhorizontal and interconnecting microstylolite networks commonly occur within the calcite veins. Equant calcite grains in the median zones exhibit indenting, truncating and also interpenetrating grain contacts. It is interpreted that the fibrous calcite veins were sourced by neomorphic calcite from their host shales, with evidence from the δ13C signatures, pressure-solution features (stylolites, microstylolites and grain contact styles) and embedded fossil ghosts within the veins. The diagenetic fluids, from which calcite was precipitated, were a mixing of the original seawaters and 18O-depleted meteoric waters. Development of bedding-parallel calcite veins is considered to have been enhanced by pressure solution as a positive feedback mechanism, which was facilitated by the overburden pressure as the maximum principal stress. Calcite fibres, with a predominant subvertical c-axis orientation, exhibit a displacive growth in porous shales and a replacive growth at vein-limestone contacts. This study highlights the critical role of pressure solution in the formation of bedding-parallel calcite veins during burial and diagenesis of immature black shales.

Critical Insights in Laboratory Shear Wave Velocity Correlations of Clays

2021 ◽  
Author(s):  
Dania Elbeggo ◽  
Yannic Ethier ◽  
Jean-Sébastien Dubé ◽  
Mourad Karray
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Earth Pressure ◽  
Dynamic Parameter ◽  
Clay Deposits ◽  
Sample Disturbance ◽  
P Rat

Shear wave velocity is an important mechanical/dynamic parameter allowing the characterization of a soil in the elastic range (γ < 0.001 %). Thirty five existing laboratory correlations of small strains shear modulus or shear wave velocity were examined in this study and are grouped into different general forms based on their geotechnical properties. A database of 11 eastern Canadian clay deposits was selected and used for the critical insights. The effect of the coefficient of earth pressure at rest was also examined. A range of variation for each general form of correlation was determined to take the plasticity index and void ratio values of investigated sites into account. The analysis shows a significant scatter in normalized shear wave velocity values predicted by existing correlations and raises questions on the applicability of these correlations, especially for eastern Canadian clays. New correlations are proposed for Champlain clays based on laboratory measurement of shear wave velocity using the piezoelectric ring actuator technique, P-RAT, incorporated in consolidation cells. An analysis of P-RAT results reveals the sample disturbance effect and suggests an approach to correct the effect of disturbance on laboratory shear wave velocity measurements. The applicability of the proposed correlations, including the disturbance correction, is validated by comparison with in situ measurements using multi-modal analysis of surface waves (MMASW).

In Situ Shear-Wave Velocity Assessment at the Delaney Park Downhole Array, Anchorage, Alaska

2020 ◽  
Vol 91 (6) ◽  
pp. 3381-3390
Author(s):  
Hai-Yun Wang ◽  
Wei-Ping Jiang
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Great Influence ◽  
Standard Penetration Test ◽  
Weak Anisotropy ◽  
Near Surface ◽  
Motion Data ◽  
Downhole Array

Abstract The shear-wave velocity (VS) in soil is an important parameter to characterize dynamic soil properties. The Delaney Park downhole array was deployed in 2003 without measuring the shear- and compression-wave velocity (VS and VP) profiles. Thornley et al. (2019) measured the VS and VP profiles using the downhole method after the sensor was removed from the 61 m borehole with casing in the array. However, the waves propagating along the casing wall may have a great influence on the recognition of the first arrival of waves propagating in the soil. Using horizontal and vertical components of weak-motion data of eight local earthquakes recorded by the array, in situ VS and VP profiles were assessed by the seismic interferometry based on deconvolution, respectively. The results are as follows. The VS and VP profiles computed by this study and measured by Thornley et al. (2019) are in relatively good agreement at a depth of 10–45 m and at a depth of 30–45 m, respectively, and in very poor agreement at other depths. The average VS profiles computed by this study are more consistent with the derived VS from the standard penetration test data at the site with slower near-surface velocities relative to the downhole logging analysis. There are strong anisotropy in the strata below 45 m and weak anisotropy with various degrees at various depths in the strata above 45 m.

An Empirical Geotechnical Seismic Site Response Procedure

2001 ◽  
Vol 17 (1) ◽  
pp. 65-87 ◽  
Author(s):  
Adrián Rodríguez-Marek ◽  
Jonathan D. Bray ◽  
Norman A. Abrahamson
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Classification System ◽  
Soil Depth ◽  
Site Response ◽  
Dynamic Stiffness ◽  
Evaluation Procedure ◽  
Site Classification ◽  
Seismic Site Response

A simplified empirically based seismic site response evaluation procedure that includes measures of the dynamic stiffness of the surficial materials and the depth to bedrock as primary parameters is introduced. This geotechnical site classification scheme provides an alternative to geologic-based and shear wave velocity-based site classification schemes. The proposed scheme is used to analyze the ground motion data from the 1989 Loma Prieta and 1994 Northridge earthquakes. Period-dependent and intensity-dependent spectral acceleration amplification factors for different site conditions are presented. The proposed scheme results in a significant reduction in standard error when compared with a simpler “rock vs. soil” classification system. Moreover, results show that sites previously grouped as “rock” should be subdivided as competent rock sites and weathered soft rock/shallow stiff soil sites to reduce uncertainty in defining site-dependent ground motions. Results also show that soil depth is an important parameter in estimating seismic site response. The standard errors resulting from the proposed site classification system are comparable with those obtained using the more elaborate code-based average shear-wave velocity classification system.

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