Imagine a skyscraper not being built on solid ground, but on the sand. The sands shift and the building collapses. This is just one of the many reasons why geotechnical investigations are so important. Geotechnical investigations are performed to determine the condition and strength of the soils and rocks that are beneath a proposed structure. In other words, it’s testing to make sure the ground can support what is being built on top of it.
Not all geotechnical investigations are alike and the investigation will be tailored to fit the project. The size, depth, and type of foundation being considered will all play a role in designing the investigation. The objective of a geotechnical investigation is to obtain information about the soils and rocks to design a safe and economical foundation for the proposed structure.
The first step in any geotechnical investigation is collecting subsurface data. This data can be collected in several ways, including drilling, test pitting, and cone penetration testing (CPT). Drilling is perhaps the most common method of subsurface exploration. A hollow drill bit is used to take samples of the soil or rock from depths up to 200 feet below the ground surface. Test pits are typically used to explore shallower depths, usually no more than 10 feet below the ground surface. CPT involves pushing a cone-shaped probe into the ground; as the probe moves further into the subsurface; readings are taken of various soil parameters such as density, water content, and strength.
Once data has been collected, it must be analyzed to make recommendations for foundation design. Soil testing is performed to determine the type of soil present (e.g., sand, clay, etc.). Site conditions are also considered, such as water table depth, proposed foundation type, etc. With all of this information in hand, a geotechnical engineer can make recommendations for foundation design that will provide satisfactory performance with an acceptable level of risk.
Who Provides Geotechnical Investigation services?
Many engineering firms offer geotechnical investigation services. Azure Group Inc. is a multidisciplinary engineering & consulting firm offering a full range of professional engineering services, including geotechnical investigations. We have a team of experienced professionals who can help you with all aspects of your project, from collecting data to analyzing it and making recommendations for foundation design.
Conclusion:
Geotechnical investigations play a vital role in ensuring that structures are built on a firm footing—literally! By understanding the subsurface conditions at a given site, engineers can design foundations that will safely support the loads imposed by a proposed structure.