Engineering FAQs

Engineering FAQs

GEOTECHNICAL ENGINEERING FAQs

What is Geotechnical due dilligence?

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.

BUILDING INFORMATION MODELLING FAQs

What is BIM?

In short, BIM is a digital representation of physical and functional characteristics of a building facility. 

Beyond the obvious benefit of thorough coordination, Tetrads BIM process focuses on some of the less advertised components. 

Accurate and faster Tender time being a key element. Using an accurate modelling approach (and higher LOD level) Clients gain benefit through great confidence in material quantities allowing more accurate tenders and subsequently less variation risk to the project.

What is LOD?

LOD stands for Level of Detail

STRUCTURAL ENGINEERING FAQs

GEOTECHNICAL ENGINEERING FAQs

What is Geotechnical due dilligence?

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.

BUILDING INFORMATION MODELLING FAQs

What is BIM?

In short, BIM is a digital representation of physical and functional characteristics of a building facility. 

Beyond the obvious benefit of thorough coordination, Tetrads BIM process focuses on some of the less advertised components. 

Accurate and faster Tender time being a key element. Using an accurate modelling approach (and higher LOD level) Clients gain benefit through great confidence in material quantities allowing more accurate tenders and subsequently less variation risk to the project.

What is LOD?

LOD stands for Level of Detail

STRUCTURAL ENGINEERING FAQs