Geotechnical testing serves as a critical means to assess the properties of soil and rock, thereby determining their capacity to support structures and foundations. The advancements in technology have led to a diverse array of testing methods available to geotechnical engineers when analysing proposed land. The suitability of testing approaches largely depends on the specific characteristics of the ground and the intended purpose.

Presently, several methodologies are employed by engineers, each with unique benefits and drawbacks. This article delves into four frequently utilised testing techniques and provides insight into selecting the most appropriate method for your project.

Standard Penetration Test (SPT)

The Standard Penetration Test (SPT) is a widely adopted and economically viable technique for soil investigation, particularly for shallow foundation projects. This method, considered as the industry standard, entails the insertion of a split-barrel sampler in the soil by means of a drop hammer. The number of blows required to advance the sampler to a specified depth is measured and serves as a primary metric for ascertaining the soil’s density and strength properties.

Cone Penetration Test (CPT)

The Cone Penetration Test (CPT) is a widely utilised method for soil investigation, renowned for its high degree of accuracy. This technique enables efficient characterisation of soil stratigraphy and estimation of foundation settlement, as it offers continuous data. To execute this method, engineers deploy a cone-shaped probe into the ground, employing hydraulic pressure. The resistance of the soil to penetration is measured, enabling the determination of the soil’s stiffness, strength, and thickness of the various soil layers. In Australia, several geotechnical engineering companies frequently employ the Cone Penetration Test for its reliability and precision.

Pressuremeter Test

The pressuremeter test is a highly adaptable and versatile soil investigation method suitable for application across a broad spectrum of soil types and environmental conditions. This technique diverges from the aforementioned methods, involving the insertion of a cylindrical probe into the soil and its inflation using either air or water. The pressure required to expand the probe is recorded, and the collected data is instrumental in evaluating the soil’s stiffness and strength properties.

Shear Strength Testing

The evaluation of shear strength is a vital aspect of slope, embankment, and retaining wall stability assessment. The process involves measuring the soil’s capacity to resist shear forces, typically accomplished through direct shear testing, triaxial testing, or vane testing.

While various geotechnical engineering companies may rely on distinct testing methods, four primary approaches are commonly employed. Determining the most suitable option hinges on several factors, such as:

  • The depth and nature of the soil or rock;
  • The structures intended use; and
  • The project budget.

Consulting a geotechnical engineer can aid in making an informed decision about the optimal testing technique for your specific project requirements.

In Australia, numerous geotechnical engineering firms offer reliable services for land testing, with BHM Geotechnical Engineering in Sydney being one of the most reputable companies renowned for delivering transparent services catering to diverse engineers needs.