EA3027 ASSESSMENT 2 - 2022/2023 Academic Session
1.0 INTRODUCTION
This assessment weighting is 50% of the course grade and contains 2 parts (Part A and Part B).
Part A – You are required to solve geotechnical problems and present your solutions in Microsoft word
or PDF format.
Part B – You are required to research one of the listed geotechnical failures and present your findings in
an 8 - 10 minutes recorded PowerPoint presentation.
2.0 SCHEDULE
Release date: 12:00 Tuesday, 22 November 2022
Submission deadline: 12:00 Thursday, 8 December 2022
Submission format: Online submission on MyAberdeen of a single file containing individual solutions to
the problems in Part A and a separate submission of the PowerPoint presentation (Part B) on Panopto.
3.0 PREAMBLES
Associated Learning Outcomes
This assessment will allow the students to demonstrate that they:
Have gained intellectual skills so that they can:
• to be able to solve problems of some complexity or with some degree of novelty in
geotechnics
Have knowledge and understanding of:
• immediate and consolidation settlement in soils
• groundwater and concept of effective stresses in soils
• the basis of most equations and charts used for solving geotechnical problems

Related Topics from the syllabus
• Engineering Geology: The rock cycle. Rock-forming minerals. Physical properties of minerals.
Classification and processes involved in the formation of rocks: igneous, sedimentary, and
metamorphic rocks. Plate tectonics. Aggregates. Groundwater. Fluviatile and coastal processes.
Site investigation, including geophysical techniques.
• The oedometer test. The compression and expansion index. Consolidation. 1-D consolidation
settlement. Degree of consolidation. Taraghi’s Theory of 1D consolidation. The log time
(Casagrande’s method) and root time method (Taylor’s method).
• Shear Strength of Soils: Internal friction. Cohesion. Coulomb's Law. Mohr circle of stress.
Conditions of failure. Triaxial tests. Direct shear test. Shear strength of normally consolidated and
over-consolidated sands and clays. Introduction to the critical state of soils.

4.0 PART A (20 Marks)

I. The results in Table 1 were obtained from an Unconsolidated Undrained (UU) triaxial compression
tests on three identical specimens of saturated soil:

Table 1.
Lateral pressure (kN/m2) 60 130 190
Total vertical stress (kN/m2) 210 281 340

a. Determine the shear strength parameters for the soil by plotting the Mohr’s circle.
[4 marks]
b. Assume that the confining pressure in the test is increased to 250 kN/m2 and 320 kN/m2,
based on your answer to (a) above, estimate the total vertical stress the sample can resist
before shearing for each of the new confining pressure. Explain your method. [3 marks]
c. From what type of soil would results obtained in (i) be expected and how can these results
be used in practice? Give explanations for your answer. [3 marks]

II. The results in Table 2 were obtained from an oedometer test on a specimen of fully saturated clay.
The moisture content at the end of the test was 28.6 %, and particle density of 2.7 Mg/m3.

Table 2.
σ' (kPa) 0 50 100 200 400 800 0
h (mm) 19.80 19.39 19.24 18.97 18.68 18.45 19.02

a) Determine the void ratio at the end of each pressure increment and plot the void ratio versus log
σ’.
[3 marks]
b) Calculate mv for each loading increment. [2 marks]
c) Calculate Cc for the normally consolidated portion. [2 marks]
d) Imagine that the specimen for the oedometer test was not fully saturated, how would this affect
the test results and the values calculated in (a) – (c) above? [3 marks]


5.0 PART B (30 marks)
A geological investigation is to be carried out for the site where a 20-storey residential building is to be
built in the city centre area of Aberdeen. You are required to carry out the following tasks:
1. Research the stages of site investigation and possible field investigation tools that will be
involved in the geological investigation for the construction of the 20-storey residential building.
2. Based on the soil mechanics laboratory experiments carried out during the laboratory practical
sessions, present the importance of sieve analysis, shear box, and triaxial tests in preventing
geotechnical failures during the construction and usage of the 20-storey residential building.
3. Present your findings in a 8- 10 minutes recorded PowerPoint presentation covering the following
key points:
Key Points
1. The introduction of stages of site investigation and general geological information around the city
centre of Aberdeen.
2. Possible field investigation tools used for the site investigation and the importance of sieve analysis,
shear box, and triaxial tests in the stability analysis of the foundation of the 20-storey residential
building in the prevention of potential failures. Specific reference should be made to the following:
data obtained from the laboratory tests, how they are processed, and the practical use of obtained
results.

Students’ presentations will be marked based on the following rubric:
• Knowledge and understanding - Thorough, comprehensive knowledge, and understanding should
be displayed by addressing key points 1 and 2. [15 marks]
• Discussion/Conclusion should be relevant, neatly drawn, and constructed. [5 marks]
• The presentation should be delivered with confidence and at a good pace; it should be clear, audible,
and well-organised. [5 marks]
• Slides should be neatly constructed, well-integrated to the talk, properly labelled and readable, and
bibliography should be well documented. [5 marks]