Installation Techniques & Methods Flashcards

What does a Proctor compaction test establish for a soil?

Answer: Maximum dry density and optimum moisture content

The Proctor test sets the maximum dry density and the moisture content that achieves it, which field compaction is measured against.

Which compaction equipment is most effective for cohesive (clay) soils?

Answer: Sheepsfoot (padfoot) roller

Sheepsfoot rollers knead cohesive soils, while vibratory equipment works best on granular soils.

What is the function of bentonite slurry when excavating a slurry (diaphragm) wall trench?

Answer: To hold the trench walls stable by hydrostatic pressure until concrete is tremied in

Slurry pressure and the filter cake it forms support the trench sides until tremie concrete displaces the slurry.

A soldier pile and lagging system is primarily used for what purpose?

Answer: Temporary earth retention for excavations

Soldier piles with timber or concrete lagging between them hold back soil along excavation walls.

A wellpoint system on a construction site is used to do what?

Answer: Lower the groundwater table to allow dry excavation

Wellpoints are closely spaced small wells connected to a header and pump that draw down groundwater.

Under OSHA 1926 Subpart P, a protective system must be designed by a registered professional engineer when an excavation exceeds what depth?

Answer: 20 feet

Sloping, benching, or support systems for excavations deeper than 20 feet must be designed by a registered PE.

When driving piles, what does reaching refusal generally mean?

Answer: The pile shows minimal penetration per blow as defined by the specified driving criteria

Refusal means penetration resistance has reached the specified blow count per unit of penetration, which indicates bearing capacity.