CEGE0031 ADVANCED SOIL MECHANICS
COURSEWORK 1 (30%):
Comparing the mechanical behaviour of the reconstituted and natural (intact) soils of a Quarternary clay (Bothkennar clay)
This is an in-depth study of reconstituted and natural soil behaviour of the Bothkennar clay, from the UK, which has been extensively studied in the 90’s. See excel spreadsheet and reference papers from Moodle, and make additional references.
Each group is required to make an oral presentation of data analyses (detail provided in section B). The final Powerpoint Slides should be uploaded to Moodle by 12 Nov Tuesday by 12:00 noon. Group presentation plus Q&A will be carried out in my office GM08 the next day on 13 Nov Wednesday. (each student needs to do a part of presentation; timeslot will be allocated later). This is 10% module mark.
The final written group report should strictly follow the structure below (as shown in section A). The word limit is 2,500 words (please state word count at the end of conclusion). Reference list, figures, tables, and appendices should be attached at the end of the report; they excluded from word count. The submission deadline of the final report is Monday 25 Nov by 12:00 noon via Moodle. This is 20% module mark.
Only one member is required to submit the presentation slides and final report, file name should clearly indicate your group number.
A. STRUCTURE OF REPORT
1 Background, around 600 words
Background should include basic information of the Bothkennar clay:
• Site location: a brief description of the sites where the soil was found.
• Geological history: the formation process of Bothkennar clay, i.e. the geological history of the soil: how and when they were deposited (sedimentation), and what happened post-deposition (post-sedimentation processes and whether there was diagenesis process).
• Site investigation: information such as composition, index properties, water content, sensitivity, and how they were obtained.
[20 marks]
2 Laboratory test results of the reconstituted soil, around 600 words
• Reconstituting process: This section will include a first paragraph describing the reconstituting process of the natural clay in the laboratory.
• Data analyses: You will analyse and describe both the compression and shearing laboratory tests of the reconstituted specimens of the clay. The data from triaxial tests on four specimens of reconstituted Bothkennar clay are available to you: B21, B22, B46 and B71. The following graphs that should be included: (a) v-lnp′, (b) q′-p′ (during both consolidation and shearing), (c) q′-εs, and q′/p’-εs (for all the shearing tests), (d) u- εs (for undrained shearing) or εv- εs (for drained shearing), and (e) secant shear stiffness vs shear strain G- εs (with εs plotted in semi-log scale).
• Discussion: You will fit your data within the Critical State framework, calculate and list in a table all Critical State parameters for compression and shearing. Make discussion of the calculated parameters of these tests and compared with published data found in the literature. Also discuss what limitations of the Critical state framework were observed.
[20 marks]
3 Test results of natural (intact) soil and comparison, around 600 words
• Sherbrooke Sampler: The data from triaxial tests on two specimens of intact Bothkennar clay are available to you: SH5 and SH13. They were recovered using a Sherbrooke sampler. You will provide a brief description of this particular method of sampling used to recover undisturbed (intact) samples, and how this sampler method is compared to the Laval sampler?
• Data analyses: You will present your analyses of the compression and shearing laboratory tests on the undisturbed specimens of the clay. The same set of graphs that should be included here are: (a) v-lnp′, (b) q′-p′, (c) q′-εs, q′/p’-εs, (d) u- εs or εv-εs (either for drained or undrained), and (e) secant shear stiffness vs shear strain G- εs (in semi-log scale).
• Discussion: Finally, you will compare your data with the corresponding specimens of the reconstituted soil presented in the previous section. Also discuss what limitations of the Critical state framework were observed.
[20 marks]
4 Effects of structure on soil behaviour, around 600 words
• Effects of natural clay structure: Briefly summarise the effects of structure during compression and shearing, and the various frameworks used to analyse clay structures.
• Data analyses: This section should include an analysis of the effects of structure on the behaviour of the natural clay and the reconstituted clay, and calculate the sensitivity of each intact sample. You will use normalised stress path plots to support your argument (graphs showing q′/pe ′-p′/pe ′ and Iv-lnp′ of both the intact and reconstituted samples should be included when making comparison).
• Discussion: Compare unique features of the structure of Bothkennar Clay, and how they compares to other natural clays.
[20 marks]
5 Conclusions, around 100 words
• You will summarise their similarities and differences of the soils within the Critical State framework.
• Total word count = XXXX
• Word count should be strictly followed: -10 marks if >2500 words, -20 marks if >10% but capped. But note reference list, tables and figures and appendices are excluded from word count, see below.
6 Reference list
7 Tables and Figures
• You must put all Tables and Figures at the end of report, figures should clearly label how you obtain each critical state parameter, and any other parameters that you discussed in the report.
• At the bottom of each figure, please include a description about the calculation steps, formulae
• And mark clearly on the figure the critical state parameters values obtained.
8 Appendices
• You can put other supporting calculation steps, formulae and assumptions you made in your calculation in appendices.
• Please submit your excel spreadsheets on a separate Tab. [20 marks]
B. PRESENTATIONS
The presentation should include some background about Bothkennar clay, your objectives e.g. how to determine the parameters for the reconstituted and intact soil. You will present graphs you have managed to produce so far, if not, parameters you were able to derive and how. If applicable, you will comment on the differences between the intact and reconstituted soil. At the end of the session you should have clear directions for your final hand-in the following week.
The presentation time is 10 minutes maximum, followed by Q&A. It is suggested 8 core slides are used: 1 slides of background information, max 5 slides for graph (a)-(e) comparing the reconstituted and intact soil behaviour in each slide, and 2 slides can be used to show the effects of soil structures on natural soil behaviour using sensitivity and soil normalisations calculations. You can also add a conclusion & references slide.
Your powerpoint slides should be submitted to MOODLE in advance (only one person in each group should upload the Powerpoint file). You are reminded to make sure that each figure has a title, all the axes labels are legible and big enough font size with correct units and there is a legend with consistent line colours and markers.
You should upload your presentation file to moodle before deadline stated on page 1, showing the up-to-date data analyses of the project. The specific timeslot of your group presentation will be announced nearer the date. The oral presentation needed to be shared between students in the group.
Marks allocations:
– 25 marks: Background and knowledge of C.S. behaviour and parameters
– 25 marks: Clear comparison of reconsituted and intact soil behaviour
– 25 marks: Knowledge of soil structures & sensitivity framework
– 25 marks:, Accuracy of data analyses and performance during Q&A
[Please rehearse timing: -5 marks if exceeds 10 mins, -10 marks if exceeds 11 minutes]
CEGE0031 Advanced soil mechanics CW1 marking criteria:
For each section, the following marking criteria applies:
Exemplary (90%-100%): Fulfilled all the required tasks with an exceptional level of insight, thoroughness, and originality. Comprehensive yet clear and concise. Impeccable English and presentation.
Outstanding (80%-89.99%): Fulfilled all the required tasks to a very high standard with no significant error but may be lacking slightly in some aspects of secondary significance (e.g. conciseness or some minor presentation flaws).
Very Good (70%-79.99%): Shows an understanding of the problem and how to solve it. Got everything right except for a few minor errors, inaccuracies or presentation flaws.
Good (60%-69.99%): Good understanding of the problem and how to solve it. Got most of the results right but made a few mistakes or showed some slight misunderstandings. Good overall presentation but maybe lacking in a few places.
Satisfactory (50%-59.99%): Shows a Satisfactory understanding of the problem and solves a significant fraction of it correctly but may contain some serious mistakes or misunderstanding. Presentation acceptable but can be poor in places.
Fair (40%-49.99%): Most requirements attempted but shows limited understanding of the problem or detailed knowledge. Contains mistakes, misunderstandings, or irrelevant material. Organisation and expression and presentation inadequately poor and standard or presentation.
Fail (0%-39.99%): Very limited understanding of the question asked and how to answer it. Some marginally relevant material and limited content but badly organised with frequent errors and misconceptions. Serious weaknesses in presentation. Also applies to submissions that are most completely irrelevant, messy or missing altogether, or submissions showing clear plagiarism.
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