Effect of Wave Attenuation on Shear Wave Velocity Determination Using Bender Element Tests
Yanbin Gao1, Xiaojun Zheng1, Hao Wang2
1Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China.
Sensors (Basel, Switzerland)
|February 15, 2022
Summary
Wave attenuation significantly impacts shear wave travel time measurements in bender element tests. For distances over 80 mm, this effect leads to inaccurate shear wave velocity (Vs) calculations in clay.
Area of Science:
- Geotechnical Engineering
- Acoustic Testing
- Wave Propagation
Background:
- Wave attenuation is common in acoustic tests, but its quantitative effect on shear wave travel time in bender element tests is under-researched.
- Accurate shear wave velocity (Vs) determination is crucial for geotechnical site characterization.
Purpose of the Study:
- To investigate the influence of wave attenuation on shear wave travel time determination in bender element tests.
- To quantify the error in Vs measurements due to wave attenuation in clay samples.
Main Methods:
- Conducted a series of bender element tests on clay samples of varying lengths under unconfined conditions.
- Analyzed the received signal's first peak and travel time using time domain methods.
- Compared peak-to-peak and arrival-to-arrival approaches for Vs calculation.
Main Results:
- Signal attenuation increased with sample length, obscuring the first peak beyond a critical distance.
- Shear wave travel time was misinterpreted for wave travel distances exceeding approximately 80 mm.
- Vs was underestimated by 17% (peak-to-peak) and 10% (arrival-to-arrival) due to attenuation.
Conclusions:
- Wave attenuation is a critical factor affecting Vs determination in bender element tests, alongside near-field effects and boundary reflections.
- Time domain methods can lead to significant underestimation of Vs in longer samples due to signal attenuation.
- Predetermining a limit test distance is advisable for specific bender element testing systems to ensure accurate Vs measurements, especially in long-distance testing.
More Related Videos
11:28A Coupled Experiment-finite Element Modeling Methodology for Assessing High Strain Rate Mechanical Response of Soft Biomaterials
Published on: May 18, 2015
12.6K
09:02Cortical Bone Assessment Using Ultrasonic Guided Waves: A Reproducibility Study in a Healthy Population
Published on: January 31, 2025
724
Related Concept Videos
01:22Relation Between the Shear and Bending Moment
1.3K
When a beam is subjected to various loads, such as a distributed load, concentrated loads, and a couple moment, it experiences both shear forces and bending moments. To understand the relationship between these two forces, we can analyze an elemental section of the beam and draw a free-body diagram.
1.3K
01:16Shear on the Horizontal Face of a Beam Element
304
To understand shear on the flat side of a prismatic beam element, consider the vertical and horizontal shearing forces, and the normal forces, acting on the element. The element's upper (U) and lower (L) sections, which are divided by the beam's neutral axis, are examined. The equilibrium of these forces is determined by applying the equilibrium equation, which helps identify the horizontal shearing force. This force is directly related to the bending moments and the cross-section's...
304
01:08Bending of Members Made of Several Materials
308
In analyzing a structural member composed of two different materials with identical cross-sectional areas, it is crucial to understand how their distinct elastic properties affect the member's response under load. The analysis involves assessing stress and strain distributions using the transformed section concept, which accounts for variations in material properties.
Hooke's Law determines stress in each material, stating that stress is proportional to strain but varies due to each...
Hooke's Law determines stress in each material, stating that stress is proportional to strain but varies due to each...
308
01:24Shear and Bending Moment Diagram: Problem Solving
2.0K
When analyzing a beam supporting concentrated loads and a distributed load, drawing the shear and bending moment diagrams is essential. These diagrams help understand the internal forces and moments acting on the beam, which is crucial for designing safe and efficient structures. Follow these steps to create the shear and bending moment diagrams:
Draw a Free-Body Diagram: Start by drawing a free-body diagram of the entire beam, including the concentrated loads, distributed load, and reaction...
Draw a Free-Body Diagram: Start by drawing a free-body diagram of the entire beam, including the concentrated loads, distributed load, and reaction...
2.0K
01:18Residual Stresses in Bending
290
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...
290
00:51Velocity and Acceleration of a Wave
4.2K
A wave propagates through a medium with a constant speed, known as a wave velocity. It is different from the speed of the particles of the medium, which is not constant. In addition, the velocity of the medium is perpendicular to the velocity of the wave. The variable speed of the particles of the medium implies that there must be acceleration associated with it.
The velocity of the particles can be obtained by taking the partial derivative of the position equation with respect to time....
The velocity of the particles can be obtained by taking the partial derivative of the position equation with respect to time....
4.2K