Site Investigation

Question 1

What is geotechnical site investigation?

Answer 1

Is the process of the collection of information, assessment and evaluating subsurface conditions for project site to assess its stability for construction and to identify potential hazards.

Question 2

Purpose/ importance of standards of codes in civil engineering practice

Answer 2

-It provides out minimum requirements to avoid inappropriate
site investigations being carried out.
-it gives systematic way of carrying out investigations using methods and techniques that reliable and cost effective
-acceptable practice
-it protects the client
-following the codes ensures a uniform basis for pricing

Question 3

Suggest a list of procedures that would be practical to implement to obtain information on surface and subsurface conditions for construction planning

Answer 3

Conducting desk study

Site visit

Planning logistics

Main ground investigation

Laboratory testing

In-situ testing

Question 4

What are commonly practiced in-situ tests in Africa?

Answer 4

Dynamic cone penetration test
Standard penetration test
Cone penetration test

Question 5

Give advantages and disadvantages of in-situ test

Answer 5

Advantages
-rapid
-inexpensive
-real time monitoring of the soil
-large volume of soil can be tested

Disadvantages
- specialised equipment and skilled operators are required
-unknown drainage conditions
-non-uniform strain applied
-no sample is recovered except SPT

Question 6

What are the advantages and disadvantages of SPT?

Answer 6

Advantages
-inexpensive
-quick and simple procedure
- N value is used to calculate/determine relative density and shear strength
- it is reliable for granular soils

Disadvantages
Soil disturbance occurs
Requires lot of time
Requires lot of physical work
It’s not reliable on cohesive soils ( sand, silt or clay)

Depth of 150m up to 450m

Question 7

You intend to conduct a desk study with your team.. Name any five documents or forms

Answer 7

Google earth
Geological map
Rainfall data
Topographical map
Previous site investigation reports in the data

Question 8

Any four surface features

Answer 8

The presence of tension cracks at the top or within the slope
Depressions on slope
Presence of curved trees trunks and leaning fences
Signs of water infiltration