Posted in Deep Foundations, Pile Driving Equipment

Concrete Pile Head Response to Impact

Our newest research item is this one, which is an expansion of the work with steel piles earlier this year. Abstract is as follows:

The application of semi-infinite pile theory to the behaviour of driven piles has been studied since Parola (1970). Most of the effort, however, has been concentrated on piles which do not require a cushion between the pile head and the pile driving accessory, such as steel piles. Concrete piles, on the other hand, are generally driven with this additional cushion. In this paper the same type of semi-infinite type of analysis is applied to this problem. Both the case of a rigid pile head and a pile head which responds without reflection from the pile are studied using both closed-form and numerical solutions. Two case histories are included which illustrate the application of the method, along with parametric studies of both pile head conditions.

You can download the paper here, or go to Researchgate to do so.

This is a new paper to update and expand on part of the first technical paper presented by a Vulcan employee: the paper “A Proposal for a Simplified Model for the Determination of Dynamic Loads and Stresses During Pile Driving,” originally presented at the 1987 Offshore Technology Conference. The abstract is here: Warrington (1987) was […]

via OTC 5395 Revisited: Analysis of Cushioned Pile Hammers — vulcanhammer.info

OTC 5395 Revisited: Analysis of Cushioned Pile Hammers — vulcanhammer.info

Posted in Pile Driving Equipment, STADYN

STADYN Project: Some GRLWEAP Screen Shots from the Original Project

While looking through some files, I found these from the original STADYN project, from the comparison case with GRLWEAP.  I’m passing these along to give you an idea of the graphical output of this program.  My thanks to Jonathan Tremmier of Pile Hammer Equipment for allowing me to use this copy of GRLWEAP.

Screenshot 2015-10-19 11.18.08
This is the “main screen” of GRLWEAP, giving a schematic view of the hammer/pile/soil system and allowing for input of parameters.

Screenshot 2015-10-19 11.18.32
This is the “bearing graph” output of the program, also giving a graphical representation of the system.

Screenshot 2015-10-19 11.19.06
This is the force-time and impedance*velocity-time trace for the pile head. Comparing the two is an important element when this data is gathered in the field.

 

Posted in Pile Driving Equipment

Pile Buck Ads 5: Vulcan 530 in Offshore Leaders

For the last of the “Pile Buck Ads,” a photo of the Vulcan 530 hammer is featured in offshore stub-type leaders.  The 530, introduced in 1978 for driving pipe piles offshore in the Gulf of Mexico, was and is used in a wide variety of pile driving projects.  In this case it’s shown to be driving concrete cylinder piles, which have become common on larger bridge projects in the last quarter century.

Posted in Pile Driving Equipment

Pile Buck Ads 4: Link Belt Diesel with a Mandrel

The fourth in our series on the ads which Pile Buck allowed vulcanhammer.net to run was this shot of a Link Belt 520 driving shell piles using the Vulcan Expanding Mandrel.   The mandrel’s history and shell piles in general are discussed here.

The Link Belt 520 is an interesting story in itself.  The diesel hammer was first developed in Germany by Delmag.  After World War II, the technology was seized as Alien Property and licensed to the Syntron concern.  They made two key changes to the diesel hammers.  The first was to use a true atomizing injection of the fuel (as opposed to the splash system common to most diesel hammers then and now) like a conventional diesel engine.  The second was to put a “bounce” chamber on top, basically a compressed air chamber to store energy on the upstroke, which was then put back into the ram during the downstroke.  This increased the blow rate and shortened the stroke.

The benefits of atomized injection were and are not clear; in some cases the Link Belt hammers were found to stop the ram before it struck the anvil, thus the hammer never impacted!  The bounce chamber mystified many engineers and inspectors in the day, but the concept was adopted by IHC for their hydraulic hammers in the 1980’s.

The Syntron hammer was sold to the crane manufacturer Link Belt, who in turn sold it to International Construction Equipment in the late 1970’s.  They still manufacture diesel hammers but they have changed the concept of the hammer somewhat since then.