Cutting Investment Risk Through Geotechnical Drilling
In some ways, geotechnical drilling is like any smart investment tool. It helps you investigate an opportunity and assess the risk before moving forward with the investment.
While I’m no expert in the origins of geotechnical drilling, I can’t help but imagine that after some construction collapse centuries ago, people began to wonder about the causes. Perhaps they came to the conclusion that they should have investigated below the surface before starting construction — thus giving birth to a new technology.
Whatever the case, geotechnical drilling has become standard practice worldwide — and, in many cases, a requirement — for any major construction investment. It’s a relatively economical and extremely accurate means of getting the most complete picture possible of subsurface conditions for any large structure, including buildings, bridges, dams, mines and oil rigs.
Investigation of soil samples, physical and structural properties of soil and rock, water tables, environmental contamination, geological formations and even seismic susceptibility enables geotechnical engineers to assess the stability and suitability of the proposed construction site and make any necessary accommodations or adjustments. Other applications for geotechnical drilling include instrumentation, rock coring and in situ testing.
Because site conditions vary greatly, most leading equipment manufacturers produce a range of rigs and tooling to meet the demands of the market.
Boart Longyear, for example, offers four multipurpose rigs suitable for geotechnical drilling, ranging from the long-trusted LX4 to the robust and versatile LX16. Each features options and versatility to address real-world site conditions.
Contractors and geotechnical engineers have relied on the LX4 (formerly known as the DB520) for over a quarter century. Over the past decade its slightly larger “cousin,” the LX6, has steadily emerged as the rig of choice for applications worldwide as one of the best, most multipurpose drilling rigs of its size in the world.
The LX6 is a compact, lightweight and versatile multipurpose drill rig designed for geotechnical investigation, construction and exploration drilling. Applications include wireline and conventional coring, undisturbed sampling and testing, geological work, ground consolidation drilling, water well drilling, auger drilling, jet grouting, micropiling and soil nailing.
Both the LX4 and LX6 use the same base and are capable of wireline and conventional coring, as well as DTH, rotary and auger drilling methods. The LX6, however, offers an upgraded mast for higher depth capacity, and a more powerful drill head for increased torque and speed.
The heavy-duty mast design and two-speed drill head of the LX6 can deliver up to 6,540 Nm (4,824 lb-ft) of torque. The pullback is 55 kN (12,364 lbf), providing a powerful drilling solution in a small and lightweight and compact footprint — only 7,650 kg (16, 856 lb) and less than 2 meters wide, providing excellent site accessibility.
A powerful Deutz D914 L04 air-cooled diesel engine produces 53 kw (71 hp) of power at 2,300 rpm. The rig also has a maximum breaking torque of 20.5 kNm (15,120 lb-ft) and 55 kN (12,364 lbf) of pullback force.
Because it is engineered for fast on-site setup, superior mobility and powerful performance, the versatile LX6 delivers increased productivity. Fast and easy changes between wireline coring, DTH drilling, flush rotary and auger drilling provide excellent flexibility from one drilling platform to another. The LX6 is also available with an automatic SPT and digital blow counter.
In addition to outstanding performance and high reliability, the LX6 is designed with an array of safety features built in. These include an intuitive control panel design, a safety cage with a sabotage-free hinge switch and multiple emergency shutdowns. The safety cage ensures drillers remain a safe distance from the drill string, while low speed and low torque rotation ensure safe rod management. In addition, the powerful steel crawlers and the LX6’s upright design ensure mobility and stability on difficult terrain and uneven formations.
Leading contractors have found the LX6 to be a vital and dependable member of their fleets as they tackle some of the world’s biggest projects. Their valuable feedback helps Boart Longyear continually improve and enhance the rig and its many features.
In Dubai, for example, the LX6 has become a reliable workhorse as the massive Palm Islands project continues to take shape on several man-made islands in the Arabian Gulf. Because of the extreme humidity and proximity to the sea, however, the contractor became concerned about susceptibility to rust. Metallization and special paint quickly addressed those concerns and made the rigs fully resistant to the environmental conditions.
Elsewhere, contractors not only push the LX6 to its recommended limits on a regular basis, but sometimes go beyond. For example, a contractor in Singapore reported that it had successfully conducted micropiling at a diameter of 350 mm — far beyond the recommended 220 mm maximum.
The Boart Longyear team was pleasantly surprised — but maybe not too surprised. After all, the LX6 keeps proving itself every day.