scholarly journals Piezoelectric Ring Bender for Characterization of Shear Waves in Compacted Sandy Soils

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1226
Author(s):  
Dong-Ju Kim ◽  
Jung-Doung Yu ◽  
Yong-Hoon Byun
Keyword(s):  
Shear Modulus ◽  
Water Content ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Shear Waves ◽  
Small Strain ◽  
The Other ◽  
Compacted Soils ◽  
Small Strain Shear Modulus

Shear wave velocity and small-strain shear modulus are widely used as the mechanical properties of soil. The objective of this study is to develop a new shear wave monitoring system using a pair of piezoelectric ring benders (RBs) and to evaluate the suitability of RB in compacted soils compared with the bender element and ultrasonic transducer. The RB is a multilayered piezoelectric actuator, which can generate shear waves without disturbing soils. For five compacted soil specimens, the shear waves are monitored by using three different piezoelectric transducers. Results of time-domain response show that the output signals measured from the RB vary according to the water content of the specimen and the frequency of the input signal. Except at the water content of 9.3%, the difference in the resonant frequencies between the three transducers is not significant. The shear wave velocities for the RB are slightly greater than those for the other transducers. For the RB, the exponential relationship between the shear wave velocity and dry unit weight is better established compared with that of the other transducers. The newly proposed piezoelectric transducer RB may be useful for the evaluation of the shear wave velocity and small-strain shear modulus of compacted soils.

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.

scholarly journals Small strain stiffness in overconsolidated Pliocene clays

2013 ◽  
Vol 45 (2) ◽  
pp. 169-181 ◽  
Author(s):  
Katarzyna Markowska-Lech ◽  
Mariusz Lech ◽  
Marek Bajda ◽  
Alojzy Szymański
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Cohesive Soil ◽  
Small Strain ◽  
Soil Parameters ◽  
Small Strain Stiffness ◽  
Triaxial Apparatus ◽  
Triaxial Cell

Abstract Small strain stiffness in overconsolidated Pliocene clays. A huge development of technical infrastructure, including the construction of many high-rise buildings, roads, railroads and extension of subway lines, took place over the recent years in Poland. Therefore, numerous planned investment projects require geotechnical data documenting the variation of soil parameters found in the subsoil. The shear wave velocity is one of the most important input parameters to represent the stiffness of the soil deposits. This paper focuses on the methods and devices using measurements of the shear wave velocity to estimate the initial shear modulus in cohesive soil. It is preferable to measure VS by in situ wave propagation tests, however it is often economically not feasible in all regions of Poland. Hence, a reliable correlation between shear wave velocity and parameters measured in triaxial cell or static penetration parameters would be a considerable advantage. This study shows results obtained from the bender elements tests and field techniques - seismic cone penetration test and seismic flat dilatometer, performed on overconsolidated cohesive soils in Warsaw. On the basis of the test results possible correlations between shear wave velocity (initial shear modulus), mean effective stress and void ratio are considered and four original empirical relationships are proposed. Moreover, the proposed formulas by two different techniques using triaxial apparatus and also RCPT cone were examined. The proposed formulas show a reasonable agreement with direct shear wave velocity profiles for clays and might be incorporated into routine laboratory and field practice

scholarly journals A novel method for determining the small-strain shear modulus of soil using the bender elements technique

2017 ◽  
Vol 54 (2) ◽  
pp. 280-289 ◽  
Author(s):  
Yejiao Wang ◽  
Nadia Benahmed ◽  
Yu-Jun Cui ◽  
Anh Minh Tang
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Shear Wave Velocity ◽  
High Frequency ◽  
Small Strain ◽  
P Wave ◽  
S Wave ◽  
Bender Elements ◽  
Small Strain Shear Modulus ◽  
First Arrival

Bender elements technique has become a popular tool for determining shear wave velocity, Vs, hence the small-strain shear modulus of soils, Gmax, thanks to its simplicity and nondestructive character among other advantages. Several methods were proposed to determine the first arrival of Vs. However, none of them can be widely adopted as a standard and there is still an uncertainty on the detection of the first arrival. In this study, bender elements tests were performed on lime-treated soil and both shear wave and compression wave velocities at various frequencies were measured. In-depth analysis showed that the S-wave received signal presents an identical travel time and opposite polarity compared with that of the S-wave components in P-wave received signal, especially at high frequency. From this observation, a novel interpretation method based on the comparison between the S-wave and P-wave received signals at high frequency is proposed. This method enables the determination of the arrival time of the S-wave objectively, avoiding a less reliable first arrival pick-up point. Furthermore, the “π-point” method and cross-correlation method were also employed and the obtained results agree well with those from the proposed method, indicating the accuracy and reliability of the latter. The effects of frequency on the shear wave velocity are also discussed.

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.

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>

Effect of Anisotropy on Shear Wave Velocity in Wood

2012 ◽  
Vol 535-537 ◽  
pp. 1923-1926
Author(s):  
Jian Ping Zhou ◽  
Jin Xia Liu ◽  
Wen Yang Gao ◽  
Zhi Wen Cui ◽  
Wei Guo Lv ◽  
...  
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Radial Direction ◽  
Rotation Angle ◽  
Wood Specimen ◽  
Shear Waves ◽  
Circular Ring ◽  
The Relationship ◽  
Intrinsic Birefringence

The velocities of shear waves propagating along radial direction of birch and elmwood specimens are measured in order to study the effect of anisotropy on shear wave velocity. The relationship between the shear wave velocity and the oscillation direction is examined by rotating an ultrasonic sensor. The results indicate that the effect of anisotropy on shear wave velocity in birch and elmwood specimens is similar to Japanese magnolia specimen. When the oscillation direction of the shear wave corresponds to the certain anisotropic direction of the wood specimen, the shear wave velocity decreases sharply and the relationship between shear wave velocity and rotation angle tends to become discontinuous. The intrinsic birefringence due to the anisotropy of birch and elmwood woods is observed. Their texture anisotropies are strong. In an isotropic nylon, on the contrary, the value of shear wave velocity was similar to a circular ring. This investigation is significant meanings in architectural and civil engineering field.

Impacts of matric suction equalization on small strain shear modulus of soils during air drying

2020 ◽  
Vol 57 (12) ◽  
pp. 1982-1997
Author(s):  
Thang Pham Ngoc ◽  
Behzad Fatahi ◽  
Hadi Khabbaz ◽  
Daichao Sheng
Keyword(s):  
Shear Modulus ◽  
Water Content ◽  
Soil Sample ◽  
Closed System ◽  
Small Strain ◽  
Matric Suction ◽  
Drying Process ◽  
Air Drying ◽  
Small Strain Shear Modulus ◽  
The Impact

In this study, a weight-control bender element system has been developed to investigate the impact of matric suction equalization on the measurement of small strain shear modulus (Gmax) during an air-drying process. The setup employed is capable of measuring the shear wave velocity and the corresponding Gmax of the soil sample in either an open system in which the soil sample evaporates freely or in a closed system that allows the process of matric suction equalization. The comparison between measurements of Gmax in the open and closed systems revealed underestimations of Gmax when matric suction equalization was ignored due to the nonuniform distribution of water content across the sample cross-sectional area. This study also investigated the time required for matric suction equalization tse to be established for samples with different sizes. The experimental results indicated two main mechanisms driving the matric suction equalization in a closed system during an air-drying process, namely the hydraulic flow of water and the flow of vapour. While the former played the key role when the micropores were still saturated at the high range of water content, effects of the latter increased and finally dominated when more air invaded the micropores at lower water contents.

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.

Measuring shear and compression wave velocities of soil using bender–extender elements

2009 ◽  
Vol 46 (7) ◽  
pp. 792-812 ◽  
Author(s):  
E. C. Leong ◽  
J. Cahyadi ◽  
H. Rahardjo
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Compression Wave ◽  
Small Strain ◽  
Reliable Determination ◽  
Digital Oscilloscope ◽  
Compression Waves ◽  
Wave Velocities

Piezoceramic elements have been used for laboratory measurement of wave velocity in soil and rock specimens. Shear-wave piezoceramic elements (bender elements) are commonly used to measure shear wave velocity for the determination of small-strain shear modulus. Compression-wave piezoceramic elements (extender elements), on the other hand, are less commonly used as compression wave velocity is less frequently measured. In this paper, the performance of a pair of bender–extender elements for the determination of both shear and compression wave velocities is examined with respect to the resolution of the recorder, bender–extender element size. and excitation voltage frequency. The evaluation showed that the performance of the bender–extender elements test can be improved by considering the following conditions: (i) the digital oscilloscope used to record the bender–extender element signals should have a high analog to digital (A/D) conversion resolution; (ii) the size of the bender–extender elements plays an important role in the strength and quality of the receiver signal, especially for compression waves; and (iii) using a wave path length to wavelength ratio of 3.33 enables a more reliable determination of shear wave velocity.

scholarly journals Characterization of Norwegian marine clays with combined shear wave velocity and piezocone cone penetration test (CPTU) data

2010 ◽  
Vol 47 (7) ◽  
pp. 709-718 ◽  
Author(s):  
Michael Long ◽  
Shane Donohue
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Small Strain ◽  
Cone Penetration Test ◽  
Research Quality ◽  
Penetration Test ◽  
Cone Penetration ◽  
Tip Resistance ◽  
Marine Clays

A database of research-quality piezocone cone penetration test (CPTU) and shear wave velocity, Vs, information for Norwegian marine clays has been assembled to study the small-strain stiffness relationships for these materials and to examine the potential use of CPTU and Vs data in combination for the purposes of characterizing these soils. Data for sites where high-quality block sampling was carried out have mostly been used. Improvements have been suggested to existing correlations between the small-strain shear modulus, Gmax, or Vs and index properties for these soils. Recent research has shown that CPTU corrected cone tip resistance, qt, and especially the pore pressure measured during CPTUs, u2, and Vs can be measured reliably and repeatably and are not operator or equipment dependant. Therefore, a new soil classification chart involving the normalized cone resistance, Qt, and normalized shear wave velocity, Vs1, or Vs1 and Δu/[Formula: see text] (where u is the pore-water pressure and [Formula: see text] is the in situ vertical effective stress) is presented. Using this chart it is possible to clearly distinguish between clays of different overconsolidation ratios (OCRs).

Sign in / Sign up

Export Citation Format

Share Document