scholarly journals Shear modulus of hydrate bearing calcareous sand-fines mixture

2019 ◽  
Vol 92 ◽  
pp. 04002
Author(s):  
Litong Ji ◽  
Abraham C.F. Chiu ◽  
Lu Ma ◽  
Chao Jian
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Hydrate Formation ◽  
Confining Pressure ◽  
Specimen Preparation ◽  
Bender Element ◽  
Calcareous Sand ◽  
Bender Element Test

This article presents a laboratory study on the maximum shear modulus of a THF hydrate bearing calcareous sand (CS)–fines mixture. The maximum shear modulus was inferred from the shear wave velocity measured from the bender elements installed in a temperature-controlled triaxial apparatus. The specimen preparation procedures were specially designed to mimic the hydrate formation inside the internal pores of CS. A trial test was conducted to validate whether the shear wave velocity is a feasible parameter to monitor the formation and dissociation of hydrate in the CS-fines mixture. Based on the bender element test results, hydrate has a more profound effect than confining pressure on enhancing the maximum shear modulus of CS-fines mixture.

scholarly journals Influence of Different Parameters on Shear Wave Velocity

2019 ◽  
Vol 8 (4) ◽  
pp. 9679-9684
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Confining Pressure ◽  
Bender Element ◽  
Damage Potential ◽  
Silt Content ◽  
Geological Conditions ◽  
Bender Element Test ◽  
Respective Field

Subsurface conditions play a major role in the damage potential of earthquakes. Local geological conditions generate significant amplification of the ground motion. The simple way to characterize the site condition is by estimating the shear wave velocity. The main objective of this paper is to evaluate the influence of silt content, density and confining pressure in the shear wave velocity. Soil samples were collected from different locations of College of Engineering, Guindy campus for conducting the bender element (BE) test. The shear wave velocity(Vs ) determined from bender element test for the respective field density were compared with shear wave velocity obtained from Multichannel Analysis of Surface Wave (MASW) test. For understanding the influence of above mentioned parameters the bender element tests were carried out. The important conclusions arrived through the studies are increase in density and confining pressure increases the shear wave velocity but increase in silt content decreases the shear wave velocity. The maximum variation in the shear wave velocity determined from laboratory and field are in the range of 11.62% to 18.5%.

Bender Element Test and Numerical Simulation of Sliding Zone Soil with Gravels of Huangtupo Landslide

2021 ◽  
Author(s):  
Yu Chen
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Small Strain ◽  
Testing System ◽  
Bender Element ◽  
Gravel Content ◽  
Consolidation Pressure ◽  
Bender Element Test ◽  
Sliding Zone

<p>In order to study the effect of the different consolidation pressure, loading-unloading path and gravel content on the shear modulus of the small strain of sliding zone soil, a set of consolidation bender element test device was developed. The device consists of three parts: a consolidation system, a deformation measuring system, and a shear wave testing system. The consolidation system is composed of a traditional consolidation instrument and the plexiglass cylinder box. The sample is cylindrical in shape and has a size of 50 mm×50 mm. The consolidation displacement is measured by a digital display micrometer. Shear wave testing system is a wave velocity measurement system made of piezoelectric ceramic. The experimental results show that the device can control the consolidation pressure and measure the vertical deformation, measure the shear wave velocity of the sliding zone soil in real-time, and then study the variation rule of the small strain shear modulus of the sliding zone soil with gravels. The shear modulus of the sliding zone soil increases with an increase in the consolidation pressure. The shear modulus of the unloading of sliding zone soil is larger than that of loading. Under the loading pressure of 200 kPa and 400 kPa, the shear modulus of the sliding zone soil first decreases and then increases with an increase in the gravel content. In the process of unloading, the shear modulus of the sliding zone soil increases with an increase in the gravel content. </p>

SHEAR WAVE VELOCITY BY TSP APPLIED BENDER ELEMENT TEST IN SAND

2006 ◽  
Vol 62 (1) ◽  
pp. 169-174 ◽  
Author(s):  
Toshihiro OGINO ◽  
Hiroshi OIKAWA ◽  
Toshiyuki MITACHI ◽  
Masaki TSUSHIMA ◽  
Kohta NISHIDA
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Bender Element ◽  
Bender Element Test

Application of the Non-Destructive Testing Method to Determine the Gmax of Bangkok Clay

2013 ◽  
Vol 418 ◽  
pp. 157-160 ◽  
Author(s):  
Keeratikan Piriyakul
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Field Test ◽  
Shear Wave Velocity ◽  
Non Destructive Testing ◽  
Bender Element ◽  
Destructive Testing ◽  
Testing Method ◽  
Bender Element Test ◽  
Non Destructive

This article presents the application of the non-destructive testing method (so called Bender element test) to measure the shear wave velocity and determine the maximum shear modulus of soft Bangkok clay samples. This research proposes the bender element technique to measure the shear wave velocity by means of piezoelectric ceramic sensors. The details of the bender element test were clearly explained. The laboratory bender element test data of the shear wave velocity were compared with the field test results and show that the field propagating waves pass along layers of higher stiffness while the laboratory test data were performed on small, possible less stiff material. The inversion calculation of the shear wave velocity in the field test is based on a linear elastic isotropic assumption which is not valid for the Bangkok subsoil and might be a second reason for the noticed differences in velocity.

Using Shear Wave Velocity to Assess the Stiffness of Soil-Cement-Fly Ash

2013 ◽  
Vol 459 ◽  
pp. 115-118
Author(s):  
Keeratikan Piriyakul
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Bender Element ◽  
Cement Type ◽  
Soil Cement ◽  
Bender Element Test

This article presents the bender element technique to determine the stiffness of Bangkok clay mixed with the Portland cement type 1 and the fly ash type F by means of shear wave velocity. The Bangkok clay was mixed with 20% by weigh of Portland cement type 1 and varied the amount of fly ash (0, 10, 15, 20, 25 and 30% by weight). The soil-cement samples were cured for 3, 7, 14, 28 and 90 days. Then, these samples were performed the bender element test. The results reported that the optimum of replacement fly ash was about 15-20% and showed that the stiffness of soil-cement-fly ash mixing was increased with increasing the curing time. However, the shear wave velocity results were higher than the result of 0% replacement of fly ash which was the long term behaviour of cement mixed with fly ash.

scholarly journals Effect of Confining Pressures on the Dynamic Response Characteristics of Niger Delta Clay Soils

2021 ◽  
Vol 5 (2) ◽  
pp. 377-386
Author(s):  
J. O. Okovido ◽  
C. Kennedy
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Niger Delta ◽  
Damping Ratio ◽  
Bender Element ◽  
Confinement Pressure ◽  
Niger Delta Region ◽  
Test Parameters

The study investigated the earthquake potential in Niger Delta region of Nigeria. A series of resonant column and bender element test was performed on compacted clay soil samples across the investigated Niger Delta States, which showed the influence of confinement on frequency, shear modulus, shear velocity and damping ratio. The confinement in clay was high. The frequency response increases with pressure increase. Also, the resonance column test at various confinements revealed changes in shear modulus, accelerometer output and damping ratio. Thus, there was high variation in the test parameters as confinement pressure was increased. Similarly, the bender element tests also showed that pressure has effect on shear wave-velocity, shear modulus and damping ratio confinement. Although, unlike Resonance Column tests, the shear modulus and shear wave-velocity generally increased as confinement pressure was increased, while for damping ratio it decreases as confinement pressure was increased. The variations in resonance column/binder element test parameters showed that the Niger Delta region, as an oil and gas area, is susceptible to earthquake. Therefore, continuous monitoring of oil exploration activities must be put in place.

scholarly journals Effect of Confining Pressures on Dynamic Response Characteristics of Silty Soils in the Niger Delta

2021 ◽  
Vol 5 (2) ◽  
pp. 404-412
Author(s):  
J. O. Okovido ◽  
C. Kennedy
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Niger Delta ◽  
Damping Ratio ◽  
Bender Element ◽  
Delta Region ◽  
Confinement Pressure ◽  
Niger Delta Region

The probability of earthquake occurrence in the Niger Delta region of Nigeria was studied in this research. The resonant column/bender element tests were used for the study. Series of analysis were carried out on compacted silt in subsoil strata obtained from various locations in Rivers, Bayelsa, Delta and Akwa Ibom States. The effects of confinement on frequency, shear modulus, shear velocity and damping ratio were studied. The tests results revealed that confinement has effects on the investigated parameters. Thus, frequency response increases with increase in confinement pressure. Also, the resonance column test at various confinements revealed changes in shear modulus, accelerometer output and damping ratio. Accordingly, there was high disparity in the tested parameters as confinement pressure was increased. Similarly, the bender element tests also showed that pressure has effect on shear wave-velocity, shear modulus and damping ratio confinement. The shear modulus and shear wave-velocity generally increased as confinement pressure was increased, while damping ratio decreases as confinement pressure was increased. The variations in Resonance Column/Bender Element test parameters showed that the silty soil in the Niger Delta region, an oil and gas rich area, is likely to experience earthquake in the future. Therefore, geological data should be collated for monitoring, especially as several geological activities take place in the region.

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.

Measurement of small-strain shear modulus Gmax of dry and saturated sands by bender element, resonant column, and torsional shear tests

2008 ◽  
Vol 45 (10) ◽  
pp. 1426-1438 ◽  
Author(s):  
Jun-Ung Youn ◽  
Yun-Wook Choo ◽  
Dong-Soo Kim
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Shear Wave Velocity ◽  
Small Strain ◽  
Resonant Column ◽  
Test Results ◽  
Bender Element ◽  
Small Strain Shear Modulus ◽  
Torsional Shear ◽  
Saturated Sands

The bender element method is an experimental technique used to determine the small-strain shear modulus (Gmax) of a soil by measuring the velocity of shear wave propagation through a sample. Bender elements have been applied as versatile transducers to measure the Gmax of wet and dry soils in various laboratory apparatuses. However, certain aspects of the bender element method have yet to be clearly specified because of uncertainties in determining travel time. In this paper, the bender element (BE), resonant column (RC), and torsional shear (TS) tests were performed on the same specimens using the modified Stokoe-type RC and TS testing equipment. Two clean sands, Toyoura and silica sands, were tested at various densities and mean effective stresses under dry and saturated conditions. Based on the test results, methods of determining travel time in BE tests were evaluated by comparing the results of RC, TS, and BE tests. Also, methods to evaluate Gmax of saturated sands from the shear-wave velocity (Vs) obtained by RC and BE tests were investigated by comparing the three sets of test results. Biot’s theory on frequency dependence of shear-wave velocity was adopted to consider dispersion of a shear wave in saturated conditions. The results of this study suggest that the total mass density, which is commonly used to convert Gmax from the measured Vs in saturated soils, should not be used to convert Vs to Gmax when the frequency of excitation is 10% greater than the characteristic frequency (fc) of the soil.

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