Module - CE 13 Soil Mechanics and Geology-11 Assignment Consolidation Test Marks 10% Learning Ability to conduct a laboratory consolidation test Outcome Ability to evaluate coefficient of consolidation and coefficient of volume compressibility of an undisturbed soil sample Ability to interpret the consolidation test data Ability to discuss the applications of the consolidation test in Programme Outcomes Assessed By: geotechnical engineering 1. Application of knowledge of mathematics, science, and engineering 1. Effective communication 1 3. In-depth technical competence in at least one engineering discipline 4. Ability to undertake problem identification, formulation and solution 5. Ability to utilize a systems approach to design and operational performance 6. Individual and team work 1 7. Understanding of the social, cultural, global and environmental responsibilities of the professional engineer, and the need for 0 sustainable development 8. Understanding of the principles of sustainable design and development 0 9. Understanding of professional and ethical responsibilities and commitment to them 1 10. Expectation of the need to undertake life-long learning and capacity to do so 0 0 not covered under this 1 covered to some extent covered to a greater extent 3 one of the main themes of the subject Lecturer Student Name Registration Number: Date of Assignment: Initial Submission Date: Prof. S. A. S. Kulathilaka Date Due: Re Submission Date: Signature Date Lecturers Remarks B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page 1 of 10
Important 1. Please note that plagiarism is treated as a serious offence and therefore the work you produce must be individual and original.. All sources of information must be referenced using Harvard Referencing where a reference list/bibliography should be included at the end of the assignment. (You may refer the information given in http://libweb.anglia.ac.uk/referencing/harvard.htm) 3. Please note that the submission date given for the assignment (14 days after the date of performance for the laboratory session) is the final date that you can submit the assignment. If the given submission date is a public holiday, redefined submission deadline will be at 1300 hr of the immediate following working day. Late submissions will be graded lower. 4. Assignments returned to students for corrections must be re-submitted within 10 days 5. Failure to re-submit the previously marked assignment with the re-submitted assignment will mean that results cannot be released for the respective unit. Plagiarism Although research and discussion form an essential part of the assignment, deliberate copying of the work of others or unacknowledged copying from printed or electronic sources is NOT permitted. Disciplinary actions will be taken against those who are found guilty of plagiarism. Signing of this sheet is required to indicate your compliance with the above regulations. Student s Signature:.. Date:. Student s Comments, (Prior to the submission) if any:........ Student s feedback, (After the the submission) if any:............ B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page of 10
CONSOLIDATION TEST SOIL MECHANICS SOIL MECHANICS LABORATORY DEPARTMENT OF CIVIL ENGINEERING UNIVERSITY OF MORATUWA SRI LANKA B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page 3 of 10
CONSOLIDATION TEST Consolidation is defined as the reduction of the volume of a soil due to the expulsion of water. This will be accompanied by the dissipation of pore water pressures. A laboratory consolidation test is performed on an undisturbed sample of a cohesive soil to determine its compressibility characteristics. The soil sample is assumed to be representing a soil layer in the ground. A conventional consolidation test is conducted over a number of load increments. The number of load increments should cover the stress range from the initial stress state of the soil to the final stress state the soil layer is expected to experience due to the proposed construction. Increments in a conventional consolidation test are generally of 4 hr duration and the load is doubled in the successive increment. In this practical class one load increment of a multi increment consolidation test is conducted and the data will be analysed to obtain the compressibility characteristics of the soil. The compressibility characteristics of the soil are; (a). Parameters needed to estimate the amount of consolidation settlement (b). Parameters needed to estimate the rate of consolidation settlement in the field. Using the data from a single load increment of the test, only the coefficient of volume compressibility m v can be estimated. Data from all the load increments should be combined to draw the e vs log σ graph and to obtain the compression index C c - the other parameter used to estimate the consolidation settlement. The rate of consolidation settlement is estimated using the Coefficient of consolidation C v. This parameter is determined for each load increment in the test. In this laboratory assignment, the coefficient of consolidation should be estimated using two methods - the root time method (Taylor's method) and the log (time) method - Casagrande's method. B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page 4 of 10
Course work report - Important points to remember 1. Outline the objectives of the test. List the equipment used in the test 3. Draw a diagram of the apparatus 4. Describe the test procedure in your own words 5. Enter the observations in the sheets provided 6. Carry out the computations, draw the necessary graphs in the sheets provided and estimate (a). The coefficient of volume compressibility for the load increment (b). The coefficient of consolidation for the increment by both the root time method and the log (time) method. 7. Discuss the importance and relevance of the test, the parameters obtained, shortcoming and possible ways of improvement. B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page 5 of 10
Laboratory Consolidation Test and Analysis Data obtained from one increment in a conventiional multi increment Consolidation Test Sample Diameter (mm) = 50.00 Initial Sample tickness (mm) = 0.00* Dial gauge reading at the stat of the test (mm) = 0.000 Dial gauge reading at the stat of the = 3.744 current increment (mm) Initial Moisture content of the sample % = 43.43 Specific gravity of the particles =.0 Current load increment is from 60 kn/m to 10 kn/m Date Time Time Elapsed (min) Root Time (min 1/ ) Dial Reading Major Minor Dial Reading (mm) Settlement (mm) 6/06/009 :00 PM 0.00 0.00 3.6 7 3.744 0.000 0.5 0.50 3.8 8 3.856 0.11 0.50 0.71 3.8 4 3.884. 0.140 1.00 1.00 3.8 6 3.94 0.180.00 1.41 3.8 94 3.988 0.44 4.00.00 4.0 38 4.076 0.33 8.00.83 4.0 94 4.188 0.444 15.00 3.87 4. 44 4.88 0.544 30.00 5.48 4. 84 4.368 0.64 60.00 7.75 4.4 6 4.41 0.668 10.00 10.95 4.4 1 4.44 0.698 1440.00 37.95 4.4 58 4.516 0.77 * Sample thickness is 0 mm at the start when the load is 0 kn/m. At the beginning of the load increment 60 10 kn/m, sample has already settled 3.744 mm and the sample thickness is 16.56 mm. B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page 6 of 10
t 90 x 0.15x B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page 7 of 10
t 50 δ 0 x x δ 50 δ 100 B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page 8 of 10
Specimen Calculations Coefficient of Volume Compressibility(m v ) h 0.7 m v = 7.91 x 10-4 m /kn H 60 16.56 Coefficient of Consolidation (C v ) a) By the Square Root Time (Taylor s) Method 1/ t t min 90 4.0 min 90 16 C v T90 d t 90 16.56 / 0.848 16 3.5mm min = 1.84 m /year b) By the Log (Time) Casagrande s Method 0 0.05mm 0.65 100 mm 0.05 0.65 50 = 0.35 mm t 50 4.68mm C v T50 d t 50 16.56 / 0.197 4.68.78 mm min = 1.46 m /year B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page 9 of 10
Marking Scheme: Measurements 35%: Calculations & Results 5%: Discussion 5%: Coursework Presentation 15%: Precision, Reliability Accuracy, Methodology, Presentation Content, Arrangement, Presentation Neatness, Clarity, Accordance to the format B.Sc Engineering, Semester IV, CE 13 Soil Mechanics & Geology - 11 Page 10 of 10