SITE WORK Flashcards
Describe a standard penetration test (SPT)
A 2 inch diameter sampler is driven into the bottom of the borehole by a hammer. The number of blows N required to drive the cylinder 1 foot down is recorded.
What are elements that the boring log records?
Material, depth encountered, moisture, density, results of borehole tests
How does a test pit work? What oshe practical limit?
Trenches dug for visual inspection of the soil…. 10 ft
What kind of soil can be tested with an augur boring?
Sand or clay in intermediate depths since the augur can’t penetrate hard obstructions
How does a wash boring work?
Penetrates deep into the soil (up to 100’) with a water jet to force up soil material. Analysis difficult because the soil is so mixed….
WITH MIXED RESULTS!
How do you perform a soil load test? And calculate design load?
Put a platform on the soil and load it progressively until settlement becomes regular. … Design load is half the test load.
What do the liquid and plastic limits refer to?
Cohesive soil … Compression and compaction values
Specific gravity …
Determines void ratio which determines compressibility
What is unconfined compression?
Measures the shear strength for cohesive soil
What are some problems caused by water in the soil?
Reduces load capacity, can cause differential settlement
Foundations below the water table are subject to…
Hydrostatic pressure
What two problems does hydrostatic pressure create?
Additional loads on structural elements… And on waterproofing as it forces water harder through any possible crack
What are some coarse grained soils and what are some fine grained soils?
Coarse: gravels and sands … Both clean and with fines
Fine: silts and clays
What does the Proctor test determine?
Optimum relationship between density and moisture content for compaction.
Describe the process of densification (+ 3 ways)
On-site compaction involving vibration, dropping heavy weights, or pounding heavy piles into the ground and filling the voids with sand
