The Geotechnical Triangle

23rd November 2020

To any geotechnical professional, the concept and application of the geotechnical triangle is key to developing a reliable ground profile model. The model is consequently used to inform safe geotechnical design. But what is The Triangle?

The Triangle

Terzaghi suggested that there are three main considerations to solving geotechnical puzzles effectively:

  1. Record of the ground profile with groundwater conditions
  2. Measuring how the ground will behave
  3. Using an appropriate model to predicting changes within the ground

To an experienced geotechnical professional, considering the above with the application of science-based judgement will result in the production of a robust ground profile model.

Therefore, putting all three aspects together forms what is known as the geotechnical triangle.

Ground Profile

The purpose of a ground investigation is to identify the nature and characteristics of the geology beneath a proposed development area. This phase includes describing the ground and groundwater conditions, and should be performed by a qualified engineering geologist.

Therefore, information from the ground investigation is collated to prepare various ground profile sections illustrating the strata layers.

Behaviour of the Ground

First of all, both field and laboratory testing data are considered. An assessment of the behaviour of soil and rock is made. Furthermore, we characterise the engineering properties of the ground. Ground water interaction with soils and rocks can be critical to understanding how the ground behaves over time and through changes in conditions.

Utilising an Appropriate Model

Firstly, a geotechnical professional will assess the ground profile and likely behaviour of soils and rocks to identify what requires modelling.

ground profileIf favourable and consistent ground is recorded, the model can be simplistic and conceptual in nature. This could rely on the use of a 2D ground profile within the overall model. Where variable or hazardous ground is recorded, the model may include complex numerical analysis and modelling. In the latter case, months of field monitoring and data may be required to predict the behaviour, movement and interactions within the ground.

Your development, regardless of scale and complexity, should be based on safe, robust and scientific design.


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