Failed Foundations: What Geotechnical Issues Can Occur?

Knowing the ground is suitable to work on is essential before starting any building project, which is where geotechnical engineering comes in. Geotechnical engineers (like us!) look at the physical, mechanical and chemical properties of the soil and rock in order to design effective foundations, groundworks and retaining walls so that your building stands the test of time.

If the characteristics and suitability of the ground isn’t tested beforehand, then this can lead to a number of geotechnical issues later down the line. Read on below as we discuss three of the common issues that could occur.



Failure of Retaining Wall

A retaining wall is a rigid support that is used to reinforce soil and increase its bearing capacity and resistance to differential settlement. They are typically used in areas where there are sloping sites, supporting the soil laterally so it can be retained at different levels on either side where it would not naturally keep to.

If the ground conditions are merely assumed rather than carefully measured, then the chances of a retaining wall failing are much greater. Before designing and building a retaining wall, the soil conditions must be accurately determined - both for the soil that is being retained and the soil that the structure is bearing on.

This is because the soil types will dictate the amount of time needed for compaction and the amount of reinforcement required from the retaining wall - both of which will have a direct impact on its overall design.

Ground Subsidence

Subsidence is the term used to describe when the ground underneath a building begins to sink, thus pulling the building down with it. When this occurs, it can extremely disrupt a building’s foundations, causing the building above to become askew and strained. The tell-tale signs of subsidence usually include large cracks in walls and sloping floors.

Though subsidence cannot always be predicted, there are certain soil types that are more prone to subsidence than others. The main culprit is typically clay soil, as its volume is highly dependent on its moisture content, so should the moisture in the soil be wicked away by tree roots or not kept hydrated due to poor surface drainage, it will begin to shrink and subsidence will likely occur.

Building on top of such soil would likely require the removal of any nearby trees and bushes, and would potentially require underpinning foundations, also.

Sinkholes

Similar though not quite the same as subsidence, sinkholes are depressions or holes in the ground that are caused by some form of collapse of the surface layer. There are a few different causes of sinkholes, but one of the most common is due to dissolution. This is when frequent exposure to rain or water that is acidic dissolves soluble rock, such as limestone.

This is why geotechnical engineers will need to identify the type of rock at a site and its average conditions (i.e. how frequently it sees surface water and experiences rainfall) to determine whether additional support is needed for building foundations.

Get in Touch

Are you looking to start a new building project in the West Midlands? Reach out to us here at Integrated Designs & Associates Ltd.

We provide a range of architectural services, structural engineering and geotechnical engineering solutions. With over 27 years of experience, you can count on us.

Get in touch with us today to enquire about our services and discuss how we can help you.