Geotechnical: Construction Phase

 

Geotechnical testing and monitoring during construction helps confirm that the actual subsurface conditions are consistent with the design model and that the geotechnical materials and systems utilized for a construction project meet the project specifications and the design intentions. Examples of construction phase geotechnical services provided by GEM include:

 

Identification of subsurface conditions that differ significantly from the design model and require improvement or design changes.

Example: The soil in the base of a footing excavation is observed and tested to confirm that it will provide the required foundation bearing capacity. Testing discloses locally soft soils. The soft soils are removed and replaced.

Verification that controlled fill meets project specifications.

Example: Specifications require floor slabs to bear on fill compacted to 98 percent maximum dry density and within 2 percent of optimum moisture content. Testing discloses low fill density due to low moisture content. Water is added and the fill is recompacted to specified value. Retesting confirms that required density has been achieved.

Confirmation that geotechnical structural systems are properly installed. 

Example: A building is supported on auger cast piles. Installation monitoring discloses that the volume of grout in several of the piles did not meet the specifications. The piles are redrilled and regrouted to the specified value.

Confirmation that ground improvement methods are properly executed and effective. 

Example: Hydrated lime treatment is used to improve the wet clay subgrade along a new roadway. Monitoring discloses a localized deposit of wet sand (old stream channel) that is not affected by the lime. Portland cement is substituted for lime in this area.

Practical, timely and cost effective geotechnical construction phase services can help keep a project on schedule when unforeseen conditions are encountered or when last-minute design changes must be quickly implemented on the construction site. A sound testing and monitoring can greatly improve new facility performance. The cost of GEM construction phase geotechnical services design is an investment in project performance.

 

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