Geotechnical drilling also known as geotechnical boring is a site investigation technique involving the drilling of any narrow shaft bored in the ground either vertically or horizontally designed to uncover the physical properties surrounding a construction site.
This process involves evaluating the soil, rock, groundwater, and overall conditions within a given depth and location. This vital work ensures construction can move forward as planned and helps catch issues before they start.
Geotechnical Soil Borings
Rotary boreholes are used where drilled exploration through rock and other solid geological formations such as dense gravel is required. Soil and bedrock samples obtained are taken to a laboratory for examination. The depth of which boreholes should be sunk is governed by the depth of soil affected by foundation-bearing pressures. Through geotechnical drilling, engineers can sample and test organic materials throughout the site, alerting contractors to unsuitable foundation soils such as loose coarse-grained soils, peats, or soft fine-grained soils. Along with this process, a coinciding geological review will map out rock formations, groundwater levels, and different types of soil throughout the site. These findings help indicate the foundation requirements of the upcoming project, including the types of tools and manpower that may be needed.
Boreholes can uncover a variety of issues prior to construction. Findings are recorded in a geotechnical boring log, and can include:
- Topographic survey data
- Boring location on site
- Soil conditions, including soil type, color, consistency, moisture levels, clay content, density, geological origin, and more
- Soil and rock strata depth
- Sample sizes and recovery methods
- Types of drills used and drilling resistance
- Water levels
The geotechnical boring log is an invaluable record for construction planning. Engineers will use these findings to evaluate:
- If the ground conditions are found to be unsuitable for the project’s scope, a new location or soil improvement will have to be considered.
- Estimating the short and long-term effects of construction on the surrounding environment helps inform proactive planning.
- Necessary equipment is required at sites. Sites that contain rock formations and dense soil may require more heavy machinery and more effort to begin work.
- Cost estimates and timelines. Working with less-than-ideal ground conditions can lead to more equipment and contractor hours, resulting in higher development, design, and construction costs and longer timelines.