Vibratory and Impact-Vibration Hammer Technology

Development of a Parameter Selection Method for Vibratory Pile Driver Design with Hammer Suspension

Letter to Michael O’Neill re Wave Equation Analysis Program for Vibratory Hammers

Survey of Methods for Computing the Power Transmission of Vibratory Hammers

Vibratory and Impact-Vibration Pile Driving Equipment

Material from the Soviet Union and Russia

Improvement of the Capacity of Vibrating Hammers for Driving Pipes Into Soils (article in English)

M.G. Tseitlin, VNIIGS
Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 6-9, May-June, 1973

It is known that vibrating hammers (impact-vibration hammers) are highly effective for driving pipes. However, their wide use is prevented by their insufficient durability and high energy consumption, which are determined mainly by the high velocity of the hammer at the moment of impact against the driven element. The results of the investigations described in this article indicate that the driving capacity of vibrating hammers in soils of medium density can be iniproved without increasing the impact velocily, by increasing the length of the path travelled jointly by the hammer and the pipe after each blow. When the vibrating hammer operates under longitudinal action, the above-mentioned effect can be obtained by adjusting the force in the springs, in case of large negative gaps. High driving capacity is possessed also by vibating hammers operating under longitudinal-rotary action, in which the path traveled jointly by the hammer and the pipe is increased. as a result of torsional vibrations of the driven pipe.

Russian Impact-Vibration Pile Driving Equipment (web page)

Vibratory Machines for Sinking Piles: Vibratory Pile Drivers (web page format)

Vibro-Engineering and the Technology of Piling and Boring Work

Mikhail Grigorevich (M.G.) Tseitlin
Vladimir Vladimirovich (V.V.) Verstov
Gennady Grigorevich (G.G.) Azbel
Stroiizdat, Leningrad Otdelenie
Leningrad, 1987
(Translated from the Russian)

1. General Information
2. Foundation of the theory of vibratory driving and extraction
3. Vibration and Impact Vibration Immersion
4. Vibratory technology for production piling
5. Vibratory Technology of the manufacture drilled works for contractors
6. Vibratory technology for the production of some appearances of special construction works

The English translation covers about half of the work.

Other Materials

Axial Response of Three Vibratory and Three Impact Driven H-Piles in Sand

Jean-Louis Briaud
Larry M. Tucker
Briaud Engineers

U.S. Army Corps of Engineeers
Miscellaneous Paper GL-88-28
August 1988

A research program to compare the ultimate axial capacity of vibratory and iumpact driven H-piles in sand was conducted at a San Francisco, CA, site. The effects of time-lapse after driving was also studied. The piles were instrumented so that both pile tip loads and load transfer along the pile could be determined.

Comparison of Axial Capacity of Vibratory-Driven Piles to Impact-Driven Piles

Reed L. Mosher
U.S. Army Corps of Engineers
Waterways Experiement Station

Technical Report ITL-87-7
September 1987

This technical report documents the findings of an investigation into the effects on the axial capacity of piles driven by vibratory pile – driving hammers. The investigation stems from the concern that foundation engineers in the Lower Mississippi Valley Division of the US Army Corps of Engineers had over the unexpected low capacities found during the pile test at Red River Lock and Dam No. 1. While driving piles with a vibratory hammer increases productivity up to 10 to 20 times over the use of an impact hammer, there is a significant reduction in the axial capacity of the piles driven with a vibratory hammer. The study revealed that this reduction was a result of a loss in the load carried by the tip . The report documents a number of pile testing programs t h a t were performed to make direct comparison between vibratory-driven piles and impact-driven piles.

Driveability and Load Transfer Characteristics of Vibro-Driven Piles

Note: this contains much of the data shown in NCHRP 316.

Daniel O. Wong
University of Houston
December 1988

Piles installed by vibration have been a foundation practice since the early 1930’s. The method has not gained wide acceptance in the U.S. because of limited understanding on driveability and load transfer mechanisms. Restriking vibro-drlven piles is very often required for analysis. A large scale laboratory study on the basic behavior of displacement piles installed with vibratory drivers compared to impact hammers and the influence of various soil and driver parameters on the behavior of piles was undertaken.

In order to achieve the desired goals, a model testing system consisting of a long sand column capable of simulating deep sand deposits, instrumented 4-in.-diameter closed-ended pile, vibratory driver and impact hammer was designed and built. Among the driver parameters investigated are frequency, bias mass and dynamic force (eccentric moment) and sand parameters such as grain size, relative density (65 and 90%) and in-situ effective stress (10 and 20 psi).

The optimum frequency for the testing conditions. selected based on the maximum rate of penetration, was 20 Hz and was independent of bias mass and soil conditions. Among the variables investigated, the relative density of sand had the greatest effect on the rate of penetration during vibro-driving. Penetration rate also increased with increasing bias mass and decreasing in-situ horizontal stress. Impact-driven piles in sand with 85% relative density developed higher resistance in compression than the vibro-driven piles, but vibro-driven plies exhibited better static performance in sand with 90% relative density. Restriking of vibro-driven piles in sand does not significantly change the compression capacity.

Four design methods to predict the bearing capacity of a vibro-driven pile have been propcsed and a procedure to select a vlbro-driver for given soil conditions Is recommended. A computer program has also been developed to model vibratory driving.

Evaluation of Bearing Capacity of Vibro-Driven Piles from Laboratory Experiments

Michael W. O’Neilll, Cumaraswamy Vipulanandan, and Daniel O. Wong
University of Houston
1990

Representative methods for predicting the bearing capacity of piles driven by vibration are reviewed briefly, and a need to establish procedures based more closely on soil properties is established. In order to investigate the influence of soil properties on piles installed by vibration, a large-scale model study was conducted in which piles were driven into a pressure chamber to simulate in situ stress conditions and subjected to loading tests. The soil, vibrator and pile properties were closely controlled. Methods were developed from pile mechanics considerations and the test data (a) to predict pile capacity and (b) to select vibrator characteristics to drive piles of known target capacities. These methods are expressed in the form of simple equations that can be applied by designers having appropriate linowledge of soil, pile and vibrator conditions. While every attempt was made in the laboratory study to simulate field conditions, field verification/calibration of the capacity prediction methods are necessary before they can be applied in practice.

Modelling of Penetration Resistance and Static Capacity of Piles Driven by Vibration at the Pioneer Freezer Site, Syracuse, NY, and Laboratory Model Tests

Michael W, O’Neill, Curnaraswmy Vipulanandan, and Reda Moulai-Khatir,
University of Houston
October 1991

Vibratory driving is a technique used for driving piles into the ground by imparting to the pile a small longitudinal vibratory motion of a predetermined frequency and displacement amplitude from a driving unit. The vibrations serve to reduce the ground resistance, allowing penetration under the action of a relatively small surcharge, or “biased” load, also provided by the driving unit, or “hammer.” Vibratory driving is especially effective in cohesionless soils and is favored over impact driving from the perspective of rapid and silent operation. However, the use of vibratory drivers has been hampered by the inability of inspection agencies to verify the bearing capacity of installed piles in the manner afforded by wave equation analysis of impact-driven piles. The current accepted practice requires restriking the vibro-driven piles with an impact hammer to verify the capacity by means of wave equation analysis or by direct dynamic monitoring. This operation increases the time required to install piles with the use of vibratory drivers and makes the process less attractive economically than it would be if some straightforward procedure were available to evaluate capacity from pile and hammer properties and simple parameters, such as rate of penetration at full penetration, that can be observed by an on-site inspector. The study reported herein aims to extend the one-dimensional wave equation approach to predict the capacity of several full-scale and model piles to demonstrate that an appropriately modified wave equation program can be used in certain cases. Further research is necessary to generalize the results of this study.

Vibro-Driveability: A Field Study of Vibratory Driven Sheet Piles in Non-Cohesive Soils

Kenneth Viking
Royal Institute of Technology

Webmaster’s note: this study is, in our opinion, the most comprehensive study to date on the subject of vibro-driveability of piles. It includes a complete literature search, laboratory testing and field testing.

The fundamental mechanisms behind the shear strength reduction in cohesionless soils using the vibratory-technique to drive sheet piles have been explained. It appears as though the key phenomena behind the shear strength reduction observed during the vibratory installation of piles is not related solely to the liquefaction induced in saturated granular soils, since the shear strength reduction has also been found in laboratory tests on air-dried granular soils.

Previously neglected, vibrator-equipment-related parameters, as well as sheetpile- related parameters significantly affecting the vibro-driveability have been discussed in the light of the effects revealed during the field tests.

The vibro-driveability results from the field studies have been compared with the two vibro-driveability models, Vibdrive and Vipere, both of which were developed at University Louvain-la-Neuve, Belgium. The semi-empirical Vibdrive model has been used to study the predicted magnitude of the soil shear-strength reduction (the penetrative resistance) during vibratory driving, and how this is affected by variation in the two fundamental mechanisms. The semi-numerical Vipere model has been used to study the predicted magnitude of (i) the variation of soil resistance over time, and (ii) penetration speed versus depth during vibratory driving. These results have been correlated with the field test results.

Vibratory Pile Driving Predictions

Geert Jonker and Simon Hartog, ICE
1988

The installation and extraction of sheetpiles and foundation piles using vibratory pile driving hammers is a commonly applied technique.

In general, the choice of the size of the hammer is based on experience. In situations where experience is limited an incorrect selection may lead to premature refusal resp. nonperformance situations, unexpectedly resulting in an increase in job-site costs.

Whereas in the past vibratory hammers were used mainly for temporary foundation purposes or for horizontally loaded structures only, there is a certain tendancy to use these hammers also for permanent systems as an alternative to impact hammers. The reason for this is not only the spetific advantages of the vibratory hammer such as:

• light in weight
• high rate of penetration
• low noise level
• low ground acceleration level

but also because the techniques for soil vibrations and vibratory hammers are understood much better than a decade or two ago.

In this respect the vibratory hammer lags far behind the impact hammer where for instance the computer simulation of the pile driving system started in the early sixties by E.A.L. Smith.

It is approximately only 3 years ago that a similar model for vibratory hammers was initiated by TNO in The Netherlands and whose programme has been fully operational since a year ago. This paper will describe the simulation programme and its use in the pile driving prediction calculations in more detail in the sections to follow.