Rock Bolts on the Panama Canal

There is no contractor in the world that hasn’t heard of the massive expansion project on the Panama Canal.  This $5.2 billion US dollar expansion will allow for the passage of today’s larger modern vessels and continue to be a source of income for the Panamanian government. The entire project is broken into seven smaller sub-projects, with this drilling is taking place on the Gaton Locks.  Excavation on the Gaton locks was started in the 1930’s by the US Corps of Engineers but was abandon after the US entered into WWII.  To continue the excavation during this century hydraulic track drills were used for the bulk of the rock removal, but the difficult rock bolting and blasting was accomplished using the HEM550 excavator drill from TEI Rock Drills. 

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By the nature of such a large project the TEI drill had to perform everyday.  After the initial commission of the drill, and a few weeks of a work, a reasonable amount of spare parts were stored on-site to keep the drill running.  Parts usage is kept to a minimum by utilizing TEI’s newly patented hydraulic drifters.  The TE550 series of drifters uses an internal hydraulic dampening system.  This revolutionary design reduces impact energy when the hammer is not engaged.  Very similar to a down the hole hammer, the TEI drifter only has full power when down pressure is applied to the drill string.  Unlike the bulky external dampening, that only acts as a shock absorber; the TEI drifter shifts the piston into an idle mode.  Providing a much more user-friendly drifter, in a shorter more simple design.

TEI Rock Drill’s patent claim for hydraulic drifters;

“An internal hydraulic dampening system that automatically reduces the power oscillation of the piston when the shank adaptor is not in the power impact position.”

Drilling was made much more difficult by the requirement that all drilling be performed from a basket.  Because of the height (up to 15 meters) of the drill holes the excavator drill by TEI was the only drill choice that could actually reach the holes.  The operator and steel tender work from an aerial lift to drill the holes and add/remove drill steels.  The holes are 115mm in diameter with some of the holes as long as 8.25 meters.  There is also an operator situated in the cab of the excavator to position the drill with the aid of radio communication from the drill basket.  It takes a very coordinated effort between these three people to make this difficult drilling work.

After the holes are drilled they are loaded with #8, grade 75, epoxy-coated bars provided by SAS Stress Steel.  These bolts have a design life of 100 years, hopefully making it until the next round of improvements on the canal in 2112.  Of course if the drilling wasn’t bad enough, loading the epoxy-coated bars into the holes presented it’s own challenges.  The drill basket returns to ground level, then drops the drill steel out of the basket and loads the bar into the basket.  Then it’s back up to the completed drill to maneuver the bar into the hole, all while avoiding damage to the epoxy coating.  A difficult process at best, but one that the operators managed with a bit of their own ingenuity.

Finally after drilling and loading the holes they would be grouted in place at the end of each day.  Which of course would entail getting a grout hose to each of the previously drilled holes.  A high-pressure Obermann grout plant was used for this purpose, the high pressure allowed the grout to continuously flow from ground level up to the various holes in the face.  And not only was the high-pressure used for adequate pumping, but also to keep the hoses clear of grout drying in the lines.  Remember this is in Panama and grout hoses stretched across a sun-baked rock floor are a combination for disaster, or at least some lost-time trying to clear the hoses.

Although this is a unique and difficult job, this project highlights the use of drilling attachments on excavators.  There are some circumstances that a drilling attachment is not the best option, but this is an example of when the excavator-mounted drill was the only option to accomplish the task.  TEI Rock Drills specializes in only building drilling attachments that use their patented hydraulic drifters.  Further enhancing the value of the excavator drill through advanced technology available today.