Topic 2b

Question 1

describe excavation

Answer 1

removal of earth from the ground for burying services, its disposal, stockpiling, backfilling and compaction

Question 2

what can excavation be classified into

Answer 2

topsoil, earth, rock and unclassified

Question 3

purposes of excavation work

Answer 3

stripping, roadwork, pit/hole, bulk and trench

Question 4

what can pit excavations be supported by

Answer 4

brickwork, reinforced concrete, precast concrete and sheet piles

Question 5

what are galvanised steel ladders used for in pit excavation

Answer 5

for maintenance purposes for inspection chambers or manholes

Question 6

what are trench excavations done for

Answer 6

buried services such as sewer lines, gas pipes and electrical cables

Question 7

what is used for a trench excavation

Answer 7

backactor or excavator

Question 8

what internal factors affect the stability of an open excavation

Answer 8

lateral earth pressure, bottom heave and erosive effects of infiltrating ground water

Question 9

what external factors affect the stability of an open excavation

Answer 9

surface surcharge, vibration load, surface water flow and groundwater seepage

Question 10

what are trench support systems governed by

Answer 10

soil and groundwater conditions, depth and width of the excavation and the surrounding conditions

Question 11

describe the purpose of backfill

Answer 11

to protect buried structures or pipes from damages due to the load above and it requires to be a suitable soil with adequate compaction

Question 12

optimum density of backfill depends on

Answer 12

soil type, moisture content, energy or weight of compaction