Geotechnical drilling is a site investigation technique designed to uncover the physical properties surrounding a construction site. Also known as geotechnical boring, this process involves evaluating the soil, rock, groundwater, and overall conditions within a given depth and location
Mud Rotary Drilling
Mud rotary drilling works much the same as air rotary drilling. The main difference is that instead of using air to remove the drill cuttings, the system uses water or another liquid medium to remove the cuttings. The system filters out the cuttings at the surface and circulates the liquid back into the hole.
This method of drilling works well in all kinds of soil, including sandy ones. The wearing that air creates is not a problem with mud rotary drilling. However, the drilling crew has to capture and dispose of the waste water used in the drilling process.
Hollow Stem Auger Drilling
When sampling is needed at shallow depths in softer formations, hollow stem auger drilling can be a good choice. The tip of the drilling equipment has a point that digs into the formation below. The cuttings travel up the spiraling wings of the stem. Once the drill reaches a given level, sampling can happen through the hollow stem.
While auger drilling is slower than rotary drilling, it does allow for quick sampling as there is no need to remove the auger. If the auger encounters saturated sand, the sand can come up the stem and cause issues.
Direct Push Drilling
Taking a profile of the soil substructure requires clean sampling. Direct push drilling is ideal. This kind of drilling uses percussion force to drive steel boring rods deep into the soil. The drilling crews can take samples of groundwater, soil, and soil gas. It is possible to use probes on the rods to take readings.
This method of drilling is quick and inexpensive. The limits are depth, hard formations, and large bore width needs.
Pile Foundation Construction
Piling is the process of driving or boring pile foundations into the ground beneath a building that is under construction. These piles transfer loads from the structure to the ground, helping to support it. Pile foundations are often used where the ground is too weak to underpin the structure.
What is the maximum depth? With the benefit of using pile joints, precast concrete piles can be driven to lengths longer than 30mx. Often concrete precast piles can be driven down to 30m, however, in special circumstances, such as offshore projects, piles can be driven down to a maximum of 150m
Micropiles, also known as minipiles, pin piles, needle piles, and root piles, are a deep foundation element constructed using high-strength, small-diameter steel casing and/or threaded bars.
Micropiles are most commonly used for structural foundation support, underpinning, wall support, and slope stabilization.
What is the difference between bored pile and Micropile?
Micropiles are defined as bored piles with diameters not exceeding 250mm. Micropiles were first constructed in Italy in 1950s and were given the name “root piles”. Whenever bored piles (larger diameter) and driven piles are considered feasible, they should be more economic than micropiles.