Location
Arlington, Virginia
Date
13 Aug 2008, 2:45 pm - 3:30 pm
Abstract
The importance of vibration problems induced by pile driving is addressed and guidelines for establishing limiting vibration levels with respect to buildings with different foundation conditions are presented. Basic concepts of pile dynamics and stress-wave measurements, which were developed for the determination of driving resistance and bearing capacity of impact-driven piles, provide important information about ground vibration induced by pile penetration. Dynamic hammer properties and geometry as well as the driving process are important for ground vibration emission from the pile. It is shown that the energy-based, empirical approach, which is still widely used by practicing engineers, is too crude for reliable analysis of ground vibrations and can even be misleading. The main limitations of the energy approach are the assumption that driving energy governs ground vibrations, the omission of geotechnical conditions and soil resistance, and the uncertainty with regard to input values. Three types of ground waves are considered when analyzing pile driving: spherical waves emitted from the pile toe, cylindrical waves propagating laterally from the pile shaft, and surface waves, which are generated by wave refraction at the ground surface at a critical distance from the pile. These three wave types depend on the velocity-dependent soil resistance at the pile-soil interface. The most important factor for analyzing ground vibrations is the impedance of each system component, i.e., the pile hammer, the pile, and the soil along the shaft and at the pile toe. Guidance based on geotechnical conditions is given as to the selection of appropriate impedance values for different soil types. A theoretical concept is presented, based on a simplified model that considers the strain-softening effect on wave velocity in the soil, making it possible to calculate the attenuation of spherical and surface waves and of cylindrical waves generated at the pile toe and the pile shaft, respectively. The concept is applied to define k-values, which have been used in empirically developed models and correlated to type of wave and soil properties. An important aspect of the proposed prediction model is the introduction of vibration transmission efficacy, a factor which limits the amount of vibration force that can be transmitted along the pile-soil interface (toe and shaft). Results from detailed vibration measurements are compared to values calculated from the proposed model. The agreement is very good and suggests that the new model captures the important aspects of ground vibration during penetration of the pile into different soil layers. Finally, based on the presented model, factors influencing the emission of ground vibrations during impact pile driving are discussed.
Department(s)
Civil, Architectural and Environmental Engineering
Meeting Name
6th Conference of the International Conference on Case Histories in Geotechnical Engineering
Publisher
Missouri University of Science and Technology
Document Version
Final Version
Rights
© 2008 Missouri University of Science and Technology, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Massarsch, K. Rainer and Fellenius, Bengt H., "Ground Vibrations Induced by Impact Pile Driving" (2008). International Conference on Case Histories in Geotechnical Engineering. 3.
https://scholarsmine.mst.edu/icchge/6icchge/session12/3
Ground Vibrations Induced by Impact Pile Driving
Arlington, Virginia
The importance of vibration problems induced by pile driving is addressed and guidelines for establishing limiting vibration levels with respect to buildings with different foundation conditions are presented. Basic concepts of pile dynamics and stress-wave measurements, which were developed for the determination of driving resistance and bearing capacity of impact-driven piles, provide important information about ground vibration induced by pile penetration. Dynamic hammer properties and geometry as well as the driving process are important for ground vibration emission from the pile. It is shown that the energy-based, empirical approach, which is still widely used by practicing engineers, is too crude for reliable analysis of ground vibrations and can even be misleading. The main limitations of the energy approach are the assumption that driving energy governs ground vibrations, the omission of geotechnical conditions and soil resistance, and the uncertainty with regard to input values. Three types of ground waves are considered when analyzing pile driving: spherical waves emitted from the pile toe, cylindrical waves propagating laterally from the pile shaft, and surface waves, which are generated by wave refraction at the ground surface at a critical distance from the pile. These three wave types depend on the velocity-dependent soil resistance at the pile-soil interface. The most important factor for analyzing ground vibrations is the impedance of each system component, i.e., the pile hammer, the pile, and the soil along the shaft and at the pile toe. Guidance based on geotechnical conditions is given as to the selection of appropriate impedance values for different soil types. A theoretical concept is presented, based on a simplified model that considers the strain-softening effect on wave velocity in the soil, making it possible to calculate the attenuation of spherical and surface waves and of cylindrical waves generated at the pile toe and the pile shaft, respectively. The concept is applied to define k-values, which have been used in empirically developed models and correlated to type of wave and soil properties. An important aspect of the proposed prediction model is the introduction of vibration transmission efficacy, a factor which limits the amount of vibration force that can be transmitted along the pile-soil interface (toe and shaft). Results from detailed vibration measurements are compared to values calculated from the proposed model. The agreement is very good and suggests that the new model captures the important aspects of ground vibration during penetration of the pile into different soil layers. Finally, based on the presented model, factors influencing the emission of ground vibrations during impact pile driving are discussed.
