Geotechnical Engineering

We provide geotechnical services for residential and commercial clients:

  • Geotechnical Due Diligence
  • Design and Build assessment
  • Geotechnical reporting for subdivision development
  • Design of shallow and deep foundation systems
  • Ground improvement design to MBIE guidelines
  • Shallow and deep ground investigation complete with geotechnical interpretive reporting
  • Retaining wall design.
  • Slope stability assessment
  • Design of steel screw piles
  • Design of bored and driven piles
  • Ground Improvement design utilising standard stone columns and cement stabilised stone columns
  • Ground Improvement design utilising reinforced gravel rafts
  • Design of hybrid foundation systems utilising ground improvement techniques
  • Liquefaction assessment and geotechnical reporting for building consent application

Q & A

What is Geotechnical Due Diligence Assessment?

We provide desktop assessment of sites for residential and commercial development by assessing the probable geotechnical hazards as sourced from the New Zealand Geotechnical Database (NZGD) and GIS websites to name but a few.  We provide a prospective client with a reasonable understanding of the subsurface ground conditions based on reference to available soil investigation information from the various web-based sources and then provide an overview of likely foundation options suitable for the client’s proposed development, based on our geotechnical assessment of the sourced material.

What is Design and Build?

We work closely with contractors to provide preliminary and final geotechnical design services for temporary works, ground improvement and foundation analysis/design. Our in-house collaboration with structural engineers provides the optimum foundation solution based on cost and performance requirements provided by either the client or from our own geotechnical investigation and reporting or from a third-party geotechnical investigation.

What is Ground Improvement?

Ground improvement is required when the ground cannot adequately support the building weight or severe ground surface damage could occur during earthquakes. Depending on the foundation performance required by the client or in accordance with appropriate design standard guidelines- MBIE as an example- ground improvement may comprise reinforced gravel raft, stone columns or deep piles.

What is a Reinforced gravel raft?

Reinforced gravel rafts are designed to provide a stabilised building platform to protect the foundation and building from ground damage caused by either unacceptable ground settlement or foundation bearing failure. The introduction of a geotextile to the gravel raft provides structural integrity to the gravel raft should ground deformation levels become unacceptable to the building performance.

What are stone columns?

Stone Columns comprise gravel inclusions in the ground, installed to a target depth as determined by the geotechnical design engineer. The stone columns help to stabilise the upper layer of soil by ‘squashing’ the soil in a horizontal direction between adjacent stone column inclusions. The effect from the combined stone columns is to stiffen the soil and improve the its’ ability to support the building whilst reducing foundation damage due to ground deformation from earthquakes or long-term ground subsidence.

What are Piles?

Piles are stiff structural elements installed in the ground to a pre-determined depth, often dictated by a stable bearing stratum. The piles serve to transfer the imposed foundation loads from ground level to the underlying stable bearing layer. Piles are often used in very weak ground susceptible to excessive ground settlement from a building’s self-weight.

CPT Testing

Ground Improvement

Screw Piles

Let’s Build Something

71 Peterborough Street
Christchurch Central City, Christchurch 8013

[email protected]

Phone number 03 365 0726
Monday to Friday 8 am to 5 pm

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Geotechnical Engineering