CCE 4004 Midterm

Land Surveying

A licensed surveyor uses a total station + GPS to capture boundaries, topography, existing utilities, and natural features

Environmental Assessment

Phase I indicates possible soil contamination and Phase II involves sampling of soil/groundwater; site cleared for construction

Subsurface investigation

Lab testing shows sandy soils; foundation depth and stabilization need special design

Site plans

Architect/engineer prepare layout, parking, landscaping, drainage, and utilities plans; stormwater BMPs minimize runoff and improve filtration

Excavation & Groundwater

if high water table discovered; wellpoints and pumps dewater to create a dry, stable excavation

Excavation support

Steel sheet piling and cofferdams provide safe excavation and limit inflow

Earthwork

foundation built; then backfilling, grading for drainage, and paving (asphalt lot) with proper subgrade/base preparation

Soil Mass

Composed of air, water, and solid particles

Atterberg Limits

LL, PL, and PI

Liquid limit

the water content of a soil when it passes from the plastic to liquid state

LL of sandy soils

less than 20

LLs of clayey soils

20 to 100

Plastic Limit

the lowest water content at which soil remains plastic

Plasticity Index

LL - PL; the amount of presence of clay in a soil

What happens at Optimum Moisture Content (OMC)

maximum density can be achieved for a given amount of compactive energy

Standard Proctor

5 ½ lb hammer
25 blows/layer
12,400 lbs effort
1/30 ft³
3 layers

Modified Proctor

10 lb hammer
25 blows/layer
56,200 lbs effort
1/30 ft³
5 layers

Specifications for OMC

acceptable range of +2% and ρ_min = 0.95ρ_d

Foundation

supports the weight of the structure and its applied loads and includes the soil or rock that a structure rests upon as well as the structural system designed to transmit building loads to the supporting soil or rock

Spread footing

a square or rectangular reinforced concrete pad that serves to distribute building loads over an area large enough so that the resulting pressure on the supporting soil does not exceed the soil’s allowable bearing strength

Pile

a column driven into the soil to support a structure by transferring building loads to a deeper and stronger layer of soil or rock, supported by skin friction and end bearing

Greatest number of U.S. construction fatalities come from

Excavation cave-ins

Excavation regulations

Sloping, shoring, shielding, and slurry trenches

Dewatering

removing water from an excavation by lowering the groundwater table before excavation begins

(Pressure) Grouting

injecting a grouting agent into soil or rock to increase its strength or stability, protect foundations, or reduce groundwater flow

4 questions for every construction operation

What are we building?
How will we build it?
What do we need?
What can go wrong?

Most commonly used parameter for specifying construction

Density

Gradation

the percent distribution in weight of individual particle sizes

Cohesive soils

small grained soils that pass the No. 200 sieve

In soil weight-volume relationships, what remains constant when moving rock and dirt?

Weight of solid particles

Why are soil and rock considered "heterogeneous" construction materials?

Because their composition and properties can vary significantly over short distances

Pier

a column typically of reinforced concrete constructed below the ground surface

Best foundation system for high water table and sandy soil

Full basement, Slab-on-grade, Deep Crawl space below the water table

Slab-on-grade

Best foundation system for dry climate and expansive clay

Unreinforced slab atop expansive clay, Shallow basement, Crawl space, Strip footing on ground surface

Crawl space

Best foundation system for cold climate and frost depth of 4 ft

Basement, Shallow slab w/ no frost protection, Surface-level spread footing, Unprotected pier blocks placed above frost depth

Basement

T/F → A floating foundation works on the principle that the weight of the structure is supported by the buoyancy of groundwater

False

Which site condition would most likely require pile foundations rather than conventional spread footings?

Firm, well-drained granular soil with high bearing capacity near surface
Shallow bedrock located approx. 3 ft below ground surface
Soft clay extending to significant depth with low bearing capacity
Dense sand that can safely support the design load with shallow footings

Soft clay extending to significant depth with low bearing capacity

Maximum Allowable slope for Stable Rock

Vertical 90°

Maximum Allowable slope for Type A

¾H:1V

Maximum Allowable slope for Type B

1H:1V

Maximum Allowable slope for Type C

1½H:1V