Remote Control Demolition Equipment Solves Tough Helical Pillar Project

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When it comes to fast and efficient deep foundation systems, helical piers are gaining traction with contractors across the country. This anchoring method provides minimal ground disturbance and leaves no waste. There is also no curing time involved – unlike micropiles or other systems – allowing for immediate loading and accelerated project timelines.

However, achieving these benefits often comes with site-specific challenges, especially in retrofit applications. Although helical pillars can be an ideal solution, it can be difficult to find electrical equipment with the power-to-weight ratio necessary to access spaces with limited emissions, such as basements and older buildings with low loads. on the ground.

It’s a problem that St. Louis-based Drilling Service Co. encountered during a recent warehouse renovation near The Hill neighborhood of the city. At first glance, the brief seemed simple: modernize a 100-plus-year-old manufacturing facility to support new equipment with heavier loads than the building was designed for. However, site-specific challenges quickly piled up, resulting in a more complex project.

The single-story warehouse, located in a traditionally industrial neighborhood near the river, likely sat on contaminated soil, requiring an installation method that limited spoil. Additionally, the facility would not permit the use of diesel-powered equipment in the building. This meant that while there was plenty of room to maneuver larger diesel-powered equipment, the selected contractor had to find an electric solution.

The general manager of the project approached Drilling Service Co. because of its long history of providing smart, efficient and effective underground solutions. The family business, now in its third generation, has served the Saint-Louis region for 66 years. During this time, the company has invested heavily in personnel and state-of-the-art technology, staying at the forefront of the drilling industry by adopting new methods to deliver safe and efficient results.

“Since our founding in 1955, Drilling Service Co. has always been focused on finding the best way to get the job done,” says Kyle Murphy, project engineer for Drilling Service Co. “The business has grown from people knew they would be treated fairly and that we could be counted on to provide cost-effective solutions for even the toughest applications.We have built relationships with general contractors throughout the region based on our integrity and our ability to deliver innovative results.”

Explore robotics

For a company synonymous with quality, customer-focused solutions for boreholes, dewatering systems, earth retention, micropiles, rock anchors and more, the warehouse renovation presented a unique opportunity. to explore an exciting new process: the robotic installation of helical pillars.

“At heart, we’re a company of problem solvers who are always looking for new ways to increase safety and efficiency,” says Murphy. “Everyone on the team brings their best ideas to the table. When we were approached with this project, we recognized it as an opportunity to explore new gear options.

Installing helical pillars requires a heavy-duty hydraulic system and a specialized drive head that can provide not only downward force, but rotational pressure as well. Drilling Service Co. has traditionally operated the drive head from the auxiliary hydraulics of a mini excavator or skid steer loader, but with the requirement of zero emissions, they knew they would have to come up with a solution. creative.

The project required digging large helical pillars consisting of a 4.5 inch diameter pipe with a 16 inch diameter helical plate 20 to 25 feet down to refuse on bedrock. After establishing the required loads, Drilling Service Co. contacted Ideal Group, the designer and manufacturer of helical pillars, to discuss equipment options.

“Ideal put us in touch with Brokk,” says Murphy. “They were using a Brokk 520D, weighing around 12,000 pounds, to test their larger helical pillars in confined spaces. Not only did it provide the torque needed, but the unique arm design meant it still had enough down pressure to operate in low-rise situations, such as a basement. That wasn’t one of our concerns with this particular project, but the electrical operation was.

Drilling Service Co. worked with Brokk to arrange a one-month rental of a Brokk 500. Ideal Group supplied a Digga with a 30ADS anchor head and custom mounting bracket.

Along with the rental, Brokk provided training to Drilling Service Co. employees at their demonstration and service center in St. Joseph, Missouri. The Drilling Service Co. team had extensive experience with hydraulic drilling equipment, which allowed them to become familiar with the basic functions. However, working with the remote operation of the Brokk robot gave them a new perspective, allowing them to step back and observe the installation from a safe distance. The training covered the specifics of the Brokk machine, including its operation, adjustment of the outriggers, use of the arm and operation of the drive head.

Ability to overcome surprises and obstacles

With their team trained and the helical pillars delivered, Drilling Service Co. was ready to get to work. The general contractor began by saw-cutting a section about 2 feet wide in the 6-inch-thick floor slab the length of each new level beam to expose the floor below. However, the plans soon hit a snag when the crew discovered a layer of urban rubble less than a foot below the slab.

“We were surprised to find fragments of cement, bricks and old rebar the size of a grapefruit to a beach ball from demolished buildings,” says Mat Boster, project superintendent for Drilling Service Co. “The propeller only has a small pitch. It could have made its way through gravel-sized rubble, but it was too big.

Drilling Service Co. quickly revised its plan. Before installing the pillars, the team had to pre-drill holes in the rubble, which was between 10 and 12 feet thick. Attaching a 16-inch-diameter corer and auger to the drive head, the team simply used the Brokk to drill through the rubble to the ground below.

“The Brokk worked great for pre-drilling,” says Boster. “It cut through the rubble quickly, so we didn’t waste a lot of time, and had more than enough power for this application as well as driving the helical pillars.”

Once the machine created a vacuum through the rubble, the lead from the spiral pile was driven into the ground below until it reached bedrock. Then 5 and 10 feet. sections were added as the installation progressed, with the team constantly monitoring the drive head and hydraulic pressure for optimum torque output.

The 23ft Brokk 500. The reach allowed the team to access coil pillar locations that would have been difficult with traditional monoboom equipment. This included reaching, over or around existing equipment in the building if necessary. The 41 kW motor was easily powered by a 100 kW generator placed outside the building.

After the jetty installation was completed, Drilling Service Co. capped the end of each pipe. The general contractor then poured the capped pipe into a level beam which was reinforced with rebar, thus becoming the basis for the facility’s new equipment.

More than half of the 46 helical pillar positions had to be pre-drilled. Thanks to the professionalism of the team and the versatility of the Brokk, the work progressed quickly, allowing Drilling Service Co. to complete the entire project in just three weeks.

Stack on projects

With one week remaining on the equipment rental, Drilling Service Co. was able to complete another helical pillar installation, this time at The Muny, a St. Louis landmark; the permanent open-air theater in Forest Park hosted its first production in 1916. A lift was being installed as part of a larger renovation project, requiring 17 helical pillars of the same size as those used for the warehouse renovation.

With the Brokk already fitted with the drive head, the team was able to move quickly to the new job site. The crew could only access the elevator shaft through a narrow pergola, so the machine’s compact size, at 5ft. 3 inches. transport width, provided a huge advantage. Additionally, the reach and maneuverability of its three-piece arm increased efficiency, allowing Drilling Service Co. to access multiple piles from one location. This minimizes repositioning of the machine in the confined space.

“With the very versatile arm, we were able to work in restricted height conditions with no problem,” says Murphy. “The only challenge was to increase the torque of the drive head to 20,000 ft-lbs. to achieve the minimum torque requirement prescribed by the designer of the helical pile. »

A quick call to Brokk’s service center in St. Joseph, and Randy Glidewell, one of Brokk’s technicians, solved this problem. Soon, Glidewell was walking them through the procedure via video chat.

“We were up and running in five minutes,” Murphy says. “Randy provided detailed instructions, down to the exact size Allen key we would need. As a company that values ​​strong customer-focused relationships, this level of professionalism and service meant a lot. »

The Muny project was completed within a week and Drilling Service Co. retuned the Brokk 500, at least until next time.

“We are definitely looking for a chance to partner with Brokk again,” Murphy said. “The electric operation and power-to-weight ratio make it ideal for restoration and retrofit applications…It’s only a matter of time before we integrate this advanced technology into our process.”

Mike Martin is Vice President of Operations at Brokk Inc.

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