Soil permeability is a key consideration for any kind of piling project, since it can have a major influence on the choice of which specific piling technique will get the best results. To define the term in a nutshell, “soil permeability” refers to the ability of soil to allow fluids, such as water or air, to pass through it. It’s a crucial property in construction and engineering, particularly in any project that involves foundations, drainage systems, and underground structures.

In any construction project that involves piling, properly accounting for the area’s soil permeability during the planning process can help to avoid a range of potential issues, including foundation failures, poor drainage, groundwater problems, and environmental degradation. Accordingly, that can help to ensure the stability, safety, and longevity of the structure being built (or reinforced, in the case of underpinning projects).

What you need to know about soil permeability

Now, different types of soil exhibit different levels of permeability, ranging from highly permeable sandy soils to less permeable soils primarily made of clay or similar materials. Highly permeable soils have large, interconnected pores, allowing fluids to flow more freely, while less permeable soils have smaller pores, restricting fluid movement.

Distinguishing the different levels of soil permeability involves using various factors, including soil particle size, structure, compaction, and moisture content. That can prove instrumental in making informed decisions regarding foundation design, drainage systems, and groundwater management.

Here’s a quick roundup of some of the most pivotal factors that influence soil permeability:

• Soil texture. As we’ve touched on above, soil with larger particle sizes, such as sand, typically has higher permeability than fine-textured soils like clay.
• Soil structure. The arrangement of soil particles affects permeability. Well-structured soils with good aggregation may have higher permeability than poorly structured soils.
• Compaction. Compacted soils have reduced pore spaces, leading to decreased permeability.
• Moisture content. Soil permeability is strongly influenced by moisture content – saturated soils typically have higher permeability than partially saturated soils.
• Organic matter. Organic matter, like compost or decaying plant material, can improve the quality of the soil. It helps soil particles stick together in clumps and creates more space for water and air to move through. This means water can drain better, and plants can get the nutrients they need.

Why is soil permeability so important in construction?

We’ve already covered some of the key reasons above why soil permeability is quite so important in construction – first and foremost, it influences which type of piling is most suitable for the job at hand. For example, generally speaking open bored auger piling is best for soils with moderate to high permeability, such as sandy or gravelly soil, whereas steel cased auger piling is best suited to soils with lower permeability, such as clays. (Bear in mind though that it’s not a hard and fast rule!)

Here’s a bit more detail on some of the key factors that soil permeability affects:

• Foundation design. The permeability of the soil directly impacts the design and performance of building foundations. Understanding soil permeability can prove vital for determining the appropriate foundation type and design parameters to ensure stability, and prevent issues such as settlement or heave.
• Drainage systems. Inadequate soil permeability can lead to poor drainage, which may result in water accumulation, soil erosion, and structural damage. Properly designed drainage systems, informed by soil permeability data, help mitigate these risks and maintain the integrity of built structures.
• Groundwater management. Soil permeability influences the movement of groundwater and its interaction with structures. High permeability soils may require groundwater control measures to prevent seepage or uplift pressures, while low permeability soils may need waterproofing solutions to mitigate moisture ingress.
• Environmental impact. Soil permeability also affects environmental sustainability, particularly in terms of stormwater management and groundwater recharge.

The details we’ve provided here aren’t exhaustive – so if you ever have any questions about soil permeability and how it might affect your piling project, don’t hesitate to ask our team here at Vxcel! Feel free to give us a call on 01254 314010, and we’ll be happy to see how we can help!

As highly experienced mini piling contractors here at Vxcel, we have well over a decade of delivering exceptional results – encompassing domestic projects, commercial properties, and industrial warehouses. To find out what we’ve achieved for previous customers, feel free to take a look through our case studies!