Pendle site Update

 

Pendle Site Update

(Image from Willmott Dixon)

It’s all happening in the ground at our Pendle site… and there’s some clever things happening below the surface too!

 

Working alongside Willmott Dixon and Menard UK, our structural engineers have developed a highly efficient foundation design for this new £18m police HQ in Pendle which incorporates the use of controlled modulus columns (CMCs) to stabilise the weak ground. This also allows shallow pad and strip foundations to be constructed, saving time, cost and materials compared to traditional piled foundations. 

CMC at Pendle

 

Controlled modulus columns (CMCs) work by creating vertical columns within the ground that enhance the mechanical properties of surrounding soil, thereby improving its load-bearing capacity and reducing settlement. Here is an overview of how they function:

  1. Installation Process: CMCs are typically constructed using a drilling method that involves inserting a casing into the ground to the desired depth. The casing is then filled with a high-strength cementitious material, often combined with additives to achieve specific properties. The columns are installed in a grid pattern across the area to be improved.
  1. Load Transfer Mechanism: Once the CMCs are installed, they act as rigid elements within the softer soil matrix. The load from the structure is transferred to these columns, which have a higher stiffness and strength compared to the surrounding soil. This load transfer helps distribute the stress more evenly across the ground, reducing the pressure on any single point.
  1. Soil Stiffening: The presence of the CMCs increases the overall stiffness of the soil because the rigid columns constrain the surrounding soil, which enhances its shear strength and reduces compressibility. The columns effectively create a composite material where the improved stiffness of the columns interacts with the properties of the surrounding soil.
  1. Settlement Control: As the load is applied to the columns, the surrounding soil undergoes consolidation. The CMCs help control the rate and magnitude of this settlement by facilitating quicker drainage and allowing pore water pressure to dissipate more efficiently, leading to reduced long-term settlement.
  1. Environmental Interaction: The installation of CMCs causes minimal disturbance to the surrounding soil, preserving its natural structure and properties. This feature is particularly beneficial in sensitive areas or where existing infrastructure must be protected.
  1. Design Flexibility: Engineers can customize the diameter, spacing, and depth of the CMCs based on the specific site conditions and loading requirements, making the system adaptable to various soil types and environmental conditions.

Overall, CMCs improve the performance of weak soils by providing a stable and stiff foundation for structures, making them a valuable tool in geotechnical engineering and ground improvement projects.

Works are progressing swiftly on site and within a couple of weeks, the foundations are due to be complete, ready for the steel framed superstructure to take shape in November and December. 

More updates to follow…

 

 

 

 

 

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