F-3 Site Layout Excavation and shoring practices

Question 1

Grading

Answer 1

refers to the surface of ground on the job site.

Question 2

Grade also means _____

Answer 2

Slope. 2% grade means that the grade drops 2mm vertically for every 100mm traveled horizontally

Question 3

Soil classifications

Answer 3

soils are classified by their particle size

Question 4

Soil testing

Answer 4

important for determining foundation design and for estimating building costs. can be done by test samples and drilling core samples

Question 5

Underpinning

Answer 5

when excavating deeper then the foundations of an adjacent building, care must be provided to maintain bearing for the buildings foundation. the process of adding sections of foundations under and existing foundation is called under pinning

Question 6

Temporary support

Answer 6

temporary support of an existing building can be provided by a series of beams placed through the wall of the building being underpinned. the beams are known as needle beams and are supported under the building on blocks, or in pits on mud crimps

Question 7

Permanent support

Answer 7

once supported, footing under the footings are made. sometimes existing footings need to be trimmed to put concrete in. this is known as leg to leg underpinning

Question 8

Excavations that require shoring

Answer 8

the depth of the excavation is what determines the shoring and sloping requirements

Question 9

Worksafe BC regulations with shoring

Answer 9

normally excavations under 1.2 meters (4ft) in depth do not require shoring.

Question 10

Engineered excavations

Answer 10

needed if

• deeper then 20 feet
• adjacent to buildings or other structures
• subject to hydrostatic pressure ( water seeping into excavation)
• being dug on sloping ground steeper then 1 vertical to 3 horizontal

Question 11

Sloping requirements

Answer 11

instead of shoring small excavations can be sloped. maximum slope is 3 horizontal to 4 vertical

Question 12

Benching requirements

Answer 12

Series of benches (stairs) down into an excavation. vertical cuts are 4 feet

Question 13

Type A: Hard and solid soils

Answer 13

Need least support. the timber shoring in this type of soil usually consists of simple uprights and cross braces.

Question 14

Type B: soils likely to crack or crumble

Answer 14

these are looser and require more support.

Question 15

Type C: soft, sandy filled or loose soil

Answer 15

soft and loose soils will constantly slough into the trench if not held back with solid planking.

Question 16

Timber and plank shoring (trench shoring)

Answer 16

this method is used when the trench is too big.normally it would be metal shoring but these wooden ones are made custom for big trenches.

planks may be spaced if soil is stable but must be close fitting if the soil is loose.

Timber shoring is slow to instal and must be installed from the top down.

Question 17

Simple shoring

Answer 17

trenches less then 2.4m (8Ft) in hard and solid soil are aloud to be built without walers. cross braces and uprights are spaced no more then 6 feet apart

Question 18

Skeleton shoring

Answer 18

constructed with uprights, walers, and cross braces. type A and B soils trenches 15 ft

Question 19

Close and tight

Answer 19

when uprights are required to be tight together

Question 20

Plywood Shoring

Answer 20

plywood can be used for uprights only if the trench is less than 2.7m (9ft). must be 3/4. upright planks are installed 24”OC

Question 21

Telescopic shoring

Answer 21

when the trench is deeper then the longest available planks. each section of planks must have at least two cross braces

Question 22

Prefab shoring

Answer 22

fasted and safest way to shore. pre made units that are lifted into trench by equipment digging them.

Question 23

Steel cage shoring

Answer 23

most common type of pre fab shoring. metal frames with solid sides. can be adjusted.

Question 24

Hydrolic shoring

Answer 24

type of prefab shoring. incorporates a hydraulic system.

Question 25

Bulk shoring

Answer 25

mainly used for constructing building foundations.

professional engineers are required because bulk shoring is needed when you cannot slope

Question 26

Raker struts

Answer 26

used to support a shoring system. bracing with steel or timbers hold up banks set on concrete or mudsils

Question 27

Rock anchors

Answer 27

better for deep excavations. drilled into sides of excavations then shoring is bolted to that.

Question 28

Sheet piling

Answer 28

interlocking sheets can be used as shoring.

- can be used to keep out water, often used for bridge pillers

Question 29

Soldiers and planking

Answer 29

another shoring method is driving wide steel beams into ground along excavation. normally 1.8m apart then 100mm thick lumber spans gaps between them.

Question 30

Small buildings foundations consist of?

Answer 30

foundation wall resting on continuous strip footing.

- width of footing is determined by type of soil that supports footing.

Question 31

position of footings on large buildings must be?

Answer 31

very deep until soil is strong.

Question 32

where is good place for water to enter site?

Answer 32

below frost line and not under carport or driveway incase it needs to be moved

Question 33

storm sewer

Answer 33

collects and removes rainwater and is often constructed of large diameter pipe. rainwater from roof flows into leaders that flow to storm sewer

Question 34

Sanitary sewer

Answer 34

is the system that handles waster water from inside the building.

Question 35

Natural gas

Answer 35

must be located, staked installed or removed by certified gas fitters.

Question 36

Calculating volume of excavated materials

Answer 36

Volume = Area of bottom + area of top / 2 x depth