Faculty of Computing, Engineering and Science

By Support

Faculty of Computing, Engineering and Science

Assessment Task

Students must view, review and analyse both the Piles in Sand and Pile in Clay laboratory experiments. Details on the requirements of the experiments are given in the appendix
Project Report
The project report will be an individual submission in report form based on the information acquired from data and presentations based on a series of laboratory sessions. It will consist of approximately 2000 words excluding figures and drawings etc and contribute a maximum of 40% to the total module mark.
1. You will be required to write up both of the experimental procedures in a formal report form in accordance with the guidance given below. The basis of the formal report each student will complete is indicated in Table-1.
2. Each student will also be required to process the laboratory results of both laboratory experiments in a clear and logical form. The results must be critically reviewed and discussed.
3. All students are required to design a pile(s) to carry a working load as given in Table-1. Note the pile will be located in a two layered soil system, sand overlying clay. The properties of each of the soils will be those obtained from the experiments. Include a critical review of the design process.
4. The piles must be designed in accordance with Euro-code 7.

Table 1

 

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Note,- for all conditions in Table 1, the water table is 1m below the surface of the clay
Learning Outcomes to be assessed (as specified in the validated module descriptor https://icis.southwales.ac.uk/ ):
Understand and apply a high degree of specialist geotechnical theory and analysis to practical situations and understand the effects of alternative solutions Critically review geotechnical data and systematically analyse the information to produce geotechnical solutions
Appendix A
Guidelines notes for writing up your work
(i) Laboratory work
• The following should be observed in all cases:
(a) Abstract/Summary of your work (consisting of statement of your aims and objectives,
how they were achieved, main findings and conclusions)
(b) Aims and objectives of experiment
(c) A very brief introduction/background consisting of only the relevant theory
(d) Description of apparatus
(e) Methodology
(f) Data, results and graphs
(g) Interpretation and discussion of results, including errors and how to minimise them
(h) Conclusions
• The instruction sheet should not be copied wholesale
• When repeated calculations are involved only one example should be presented/demonstrated
• All work must be well presented in terms of language, style, layout and meaningfulness of graphs and charts
• You must demonstrate evidence of research through use of appropriate references – which must be properly cited
(ii) Non-laboratory work
• The following should be observed in all cases:
(a) Abstract/Summary of your work (consisting of statement of your aims and objectives, how they were achieved, main findings and conclusions)
(b) Introduction, including a relevant and critical literature review
(c) Main body of work consisting of critical examination/presentation of the issues involved
(d) Discussion and conclusions
• All work must be well presented in terms of language, style, layout and meaningfulness of quotations, graphs and charts.
• You must demonstrate evidence of research through use of appropriate references – which must be properly cited.

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Appendix B Piles in Sand – Coursework Detail
General
The apparatus consists of a large sand tank with a steel template held in a frame above the sand surface. The template has 13 symmetrically placed holes through which nine 12.5mm diameter steel piles are driven into the sand in a pre-selected pattern. The piles are driven using a small hand powered pile driver. A loading plate can be attached to an individual pile enabling it to be loaded to failure. The resistance to driving can be measured for each pile in the group and the densifying effect of driving piled in sand can be demonstrated. Load/ settlement curves can be drawn and relationships can be analysed between penetration resistance, load bearing, settlement and pile group behaviour.
Procedure
1. Remove or loosen sand to a depth of 450mm. Replace and or compact the sand to a uniform density.
2. Place the pile guide plate in the frame of the sand tank and select the order and pattern in which the piles are to be driven.
3. Drive each one of the nine piles to the set length using the dynamic driving system and record the blow count per 50mm of penetration.
4. Select two piles for load testing and load test each of these piles using the following procedure.
5. Attached the load plate on top of the pile and set up the dial gauge.
6. Apply load in increments to the pile until failure conditions are reached ie settlement becomes excessive in relation to the increase in load.
7. For each load increment record the pile head displacement.
Tasks
1. Produce a report in accordance with Appendix A which will include the following:
2. Produce a graph of blow count verses penetration for each of the piles.
3. Plot a graph of settlement verses load and evaluate the failure load for each of the two piles load tested.
4. Compare the failure load to that determined using the bearing capacity formula.
5. Inspect the relative performance of each pile in terms of load and settlement.
6. Critically review and discuss the results
Note – The results of a shear box test on the sand (not shown in the video) indicate an angle of
internal friction for the sand of 33degrees, φ’=33o
Model Pile In Clay – Coursework Detail – General Procedure
The experiment is based on the constant rate of penetration test, which is one of the methods commonly used to test piles in the field. The equipment used for the laboratory CRP test consists of a CBR mould filled with clay, a circular steel pile etched at 25mm intervals, a 5tonne loading frame and a triaxial for measuring the unconfined compressive strength of the clay. The pile is placed at the surface of the clay, the rate of penetration is then set at 1.5mm/minute and the pile is driven at that speed into the clay for 4 mm while the load/penetration readings are recorded. The pile is then driven rapidly into the clay until the 25mm mark is reached. The rate of penetration is set again at 1.5mm/minute and the pile is driven at that speed into the clay for 4 mm while the load/penetration readings are recorded. The pile is next driven rapidly in the 50mm mark and the load/penetration is again read for 4mm penetration at 1.5mm/minute. The process is further repeated for a penetration of 75mm. The pile is withdrawn and the soil is removed from the mould and is tested for the unconfined compressive strength. Load/penetration graphs can be plotted and the ultimate loads can be determined. Evaluation of the shear strength from the unconfined compressive tests enables values of the adhesion factor to be found and comparisons of experimental and design loads to be made. A comparison of the ultimate failure loads can be made with the following equation:-

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Procedure
1. Set up the 12.5mm diameter pile in the CBR apparatus, which will enable the pile to be driven
in a mould containing clay.
2. With the pile at the surface of the clay, perform a constant rate of penetration test for a rate of 1.5mm/minute. i.e. record load for every 25 divisions of displacement until failure conditions are observed or for a total penetration of 4mm. Then drive the pile 25mm into the clay and record the maximum load on the proving ring. Release the load and then perform another constant rate of penetration test for a rate of 1.5mm/minute until failure conditions are observed.
3. Repeat the above for at pile penetrations of 50mm and 75mm.
4. Remove the pile and establish the un-drained shear strength of the clay via UU Triaxial tests.
Tasks
1. Produce a report in accordance with Appendix A, which will include the following:
2. Plot a graph of settlement verses load and evaluate the failure load for each of the load tests.
3. Compare the failure load to that determined using the bearing capacity formula.
4. Inspect the performance of each pile in terms of load and settlement.
5. Evaluate the Undrained Cohesion (Cu) and adhesion factor () for the soil pile system.
6. Critically review and discuss the results.
Note – A separate report/description of the Unconsolidated Undrained Triaxial tests is not required. Simply state in the Model Pile In Clay Methodology ‘UU Triaxial tests were undertaken, the results and plots for these tests are in Appendix ?? and a Cu of ??kN/m2 was determined for the design’

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