Site Investigations

Question 1

Topography

Answer 1

The surface features of an area

Question 2

Greenfield

Answer 2

Sites which have not previously been built on

Question 3

Brownfield

Answer 3

Sites which have been previously built on and may now be disused or derelict

Question 4

Subsidence

Answer 4

The downward movement of the ground on the site that is not related to the weight of the building

Question 5

Settlement

Answer 5

Consolidation or decrease in the volume of the soil due to the weight of the building

Question 6

Conservation area

Answer 6

An area designated by the local planning authority as historical or for architectural interest

Question 7

Greenbelts

Answer 7

Non-built areas around towns and cities to protect the environment and prevent urban sprawl

Question 8

Sites of Special Scientific Interest (SSSI)

Answer 8

Sites protected by law to conserve wildlife or geology

Question 9

Borehole report

Answer 9

Provides information on the soil types and depths within various strata underneath the surface of the site

Question 10

External envelope

Answer 10

The walls and roof of forming the external surfaces of a building, including features such as the windows and external doors

Question 11

Ground conditions

Answer 11

soil type, composition, contamination, level of compaction, water table level, level of saturation

Question 12

Ground water table

Answer 12

The depth below ground level of water contained in the ground

Question 13

Sub-soil

Answer 13

Soil below the topsoil

Question 14

Bearing pressure

Answer 14

Pressure on soil caused by load

Question 15

Bearing capacity

Answer 15

The amount of load the ground can carry

Question 16

What is the difference between ground investigation and site investigation?

Answer 16

GI is concerned with the properties of the ground, whereas site investigation is to do with all aspects of the location

Question 17

What is the significance of site investigation? Why? (2)

Answer 17

1. To highlight unfavourable ground conditions or hazards (EG soft ground, contamination. 2. To obtain data that enables design team to build structures

Question 18

What is the purpose behind completing a site investigation? (4)

Answer 18

1. Saves money - gives u info to figure out if soil treatment necessary. 2. Provides background - to improve safety of project. 3. Reduces damages - buildings on bad soil’s foundations can be damaged in the future. 4. Assist in determining construction materials - identifies which materials should be used in construction

Question 19

What are the risks of a potential site? (7)

Answer 19

1. Nature and condition of the soil is unknown. 2. Bad SI could cause geotechnical and structural problems. 3. Brownfield sites may need to be sealed and ground decontaminated. 4. Site may be in a flood plain. 5. Potential earthquake or tremor region. 6. Ground water levels. 7. Misunderstandings, delays, and extra cost

Question 20

Information required from a site investigation (7)

Answer 20

1. Ground properties, 2. Topography of site, 3. Location of services, 4. Chemical constituents of soil, 5. evidence of contamination, 6. position of groundwater, 7. Position of any tree roots

Question 21

Walk-Over Survey

Answer 21

Walking the site on foot, making notes on relevant things for the project. This allows experienced surveyors to get a feel of the ground condition.

Question 22

sub-soil investigation, why?

Answer 22

To figure out soil type, consistency, structure, moisture conditions, presence of roots. From these we can find bearing capacity, seasonal changes and possible ground movements.

Question 23

Window sampling (sub-soil investigation)

Answer 23

Boring (sticking a hollow tube through) shallow soft soils to investigate the substrata in order to gain a profile of the ground conditions and to facilitate soil sampling for chemical and geotechnical analysis

Question 24

Trial pits

Answer 24

dug to 3-4m, sides of excavations inspected, soil samples tested, do sides collapse? does trench fill with water?

Question 25

Bore Holes

Answer 25

Drilled down and sealed, can go 30m in depth, through soil, sand/gravel, water bearing strata

Question 26

Pressure bulb

Answer 26

the area to which applied load can move soil through pressing down. If the downward pressure is too great compared to the bearing pressure of the soil, then settlement occurs.

Question 27

What aspects of soil would you wanted tested in a lab? (6)

Answer 27

1. Soil classification (consistency, particle size etc), 2. Shear strength (resistance to erosion, cohesiveness), 3. Internal friction (sand/large, clay/small) 4. Compressibility (squeezing out air/water) 5. Permeability (water travelling through voids) 6. Contamination (previous use/chemical makeup)

Question 28

Solid Rock (soil type) (3)

Answer 28

Levelling difficulty, cavities would require filling, can be problematic to combine

Question 29

Gravels (soil type) (3)

Answer 29

High bearing capacity, less risk of long term settlement, can be undermined by water flow/table

Question 30

Sands (soil type) (4)

Answer 30

Smaller angular particles, good bearing capacity, classified into compact or loose, can be affected by water and frost

Question 31

Silts (soil type) (4)

Answer 31

Fine particles, low bearing capacity, prone to shrinkage/swelling by water content, weak to frost

Question 32

Clays (soil type) (4)

Answer 32

Microscopically small particles, stiff firm and soft, can change in volume massively from moisture content, can suffer very slow settlement

Question 33

Peats (soil type) (1)

Answer 33

vegetable matter with no bearing capacity, formed from partially decomposed material under water saturated conditions.

Question 34

Dead load

Answer 34

These are loads that are stationary and permanent

Question 35

Live load

Answer 35

Temporary or movable loads that act on the structure as its being used (people, furniture)

Question 36

Environmental loads

Answer 36

wind/snow/ground/vibration.

Question 37

Cohesive soils

Answer 37

Clay, silt, peat - microscropic size of particles makes water cling to them. Can suffer very slow settlement. Contain large volumes of water, shrinkage and swelling, stable and good texture, generally stable at 1m depth

Question 38

Non-cohesive soils

Answer 38

Gravel and sands. Much larger size and when loaded, shape makes them lock together, water drains out of them, high bearing capacity, frost can have a problem 600-750mm depth

Question 39

Constraints to design/construction (5)

Answer 39

Planning constraints, statutory constraints (EG building regulations, CDM), environmental constraints (air,noise,water pollution), Social Constraints (Neighbours rights, community objections), budget constraints (local prices, life cycle costs