tw58 university of bolton school of engineering beng (hons) civil engineering semester ... ·...
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TW58
UNIVERSITY OF BOLTON
SCHOOL OF ENGINEERING
BENG (HONS) CIVIL ENGINEERING
SEMESTER 2 EXAM 2015/2016
GROUND & WATER STUDIES 2
MODULE NO: CIE5005 Date: Tuesday 17 May 2016 Time: 10.00 – 1.00
INSTRUCTIONS TO CANDIDATES: There are TWO Sections; A and B. You will be supplied with TWO Answer Booklets by
the Invigilator. Answer Section A in ONE Answer Booklet, and Section B in the other.
Section A : Q1 to Q4 (Answer THREE Questions
from four). Section B : Q5 to Q7 (Answer TWO Questions from
three). Formulae and Definitions are provided. Lined Graph Paper and Supplementary Answer
Sheets are available for your use. Ensure that you write your Candidate Number or
Desk Number on each Figure, Supplementary Sheet or Sheet of Graph Paper you use to answer the selected questions.
All questions carry equal marks. Marks for parts of questions are shown in
brackets.
Page 2 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
SECTION A
Question 1
i. With the aid of sketches explain what is meant by the boundary layer and it’s importance in pipeline hydraulics. (5 marks)
ii. The discharge of water passing through a horizontal 225Φ pressurised main varies from 0.4l/s to 22l/s.
a. Sketch the pipeline velocity profile for these maximum and minimum flows, taking the dynamic viscosity µ to be 1.14x10-3 kg/ms. (8 marks)
b. Determine the headloss is each case if the pressurised main is 80m long and has a ks
value of 1.3mm. (7 marks)
1
√λ= −2log (
ks3.7d
+5.1286
Re0.89)
Total 20 marks
Question 2
i. Explain the term ‘Sustainable Urban Drainage System’, giving some examples of the technique. (8 marks)
ii. Using the Rational Method of design, check the suitability of the drainage design in Table Q2 and select a suitable pipe diameter for pipe 1.2. The rainfall return period is 1 in 10 years, the time of entry is 6.0 minutes and the pipe roughness ks is 1.5mm. HRS tables and a rainfall table are provided. nb (12 marks)
Total 20 marks
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Page 3 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Question 3 A pipe network System A is shown below in Fig Q3a. Using the information given in Table Q3b
i. State the basic hydraulic principles which apply in water network analysis. (4 marks)
ii. Make a sensible first estimate for the head at the pipe junction in System A. Briefly explain
the reasons for your selections. (2 marks)
iii. Ascertain a first estimate of the level of error in your initial assumption using Table Q3c. Explain how you have determined the errors, what the errors mean. (12 marks)
iv. Determine the correction factor for pipe junction height. (2 marks)
Fig Q3a System A
Pipe Length
(m) Diameter
(mm) Roughness
(mm) Reservoir
Water level AOD (m)
A 720 300 1.5 1 305
B 560 200 1.5 2 289
C 650 200 1.5 3 284
Table Q3b
Total 20 marks
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A
B
C
1
2
3
Page 4 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Question 4
i. A 300Φ sewer, length 220m and roughness ks of 1.5mm, is laid at a gradient of 1 in 125. Determine the ‘full bore’ capacity of the pipe and the height of surcharge in the upstream manhole when the flow in the sewer is 111 litres/sec. (HRS tables are provided)
(8 marks)
ii. Water flows through a 200mm diameter pipe at a rate of 40litres/sec. The pipe is 400m long and has a Darcy friction factor λ of 0.022. It is proposed to increase the flow through the pipeline to 55litres/sec, without increasing the friction loss, by the addition of a parallel pipeline of the same diameter and λ value as the existing pipeline. Determine the length of pipe required. (12 marks)
Total 20 marks
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Page 5 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Pipe No
Pipe length
(m)
Pipe gradient (1 in )
Vel (m/s)
Time of
flow (min)
Time of
Conc. (min)
Rate of rainfall
i (mm/hr)
Imp. Area (ha)
Cum. Imp. Area
AP (ha)
Flow Q
(l/s)
Pipe dia.
(mm)
Pipe
Capacity
(l/s)
1.0 95 83 0.08 150
1.1 69 67 0.13 225
2.0 150 83 0.18 225
2.1 110 56 0.12 225
1.2 76 50 0.14
Table Q2
TO BE HANDED IN WITH ANSWER BOOK Candidates ID No.………………………………
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Page 6 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Pipe hf across
Pipe (m)
SO
(1 in)
Q
(litres/s)
Q
(m3/s)
A
B
C
Error in Q
Table Q3c
TO BE HANDED IN WITH ANSWER BOOK Candidates ID No............................................
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Page 7 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Page 8 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
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Page 10 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
END OF PART A QUESTIONS
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Page 11 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
SECTION B
Question 5 i) Explain the purpose of “Mohr’s stress circles”. Sketch a Mohr’s stress circle diagram
for the situation where a triaxial compression test on a cylindrical clay sample has a
hypothetical shear plane inclined at an angle of from the horizontal. Ensure that you label all axes and key points on your sketch diagram and denote the direction of the principal stresses so that your diagram clearly indicates the purpose of having plotted the diagram.
(5 marks)
ii) A series of ‘quick’ unconsolidated undrained triaxial tests were conducted on a sample of saturated clay with the results obtained being as follows:
Test Number 1 2 3
Cell Pressure (kN/m2) 30 60 120
Vertical Stress at Failure (kN/m2) 121 154 215
Using a sheet of graph paper and constructing Mohr’s stress circles, determine the shear strength parameters of the soil sample and thus describe the soil strength using geotechnical terminology.
(8 marks)
iii) Describe the full range of shear strength testing methods available for testing clays in the field and in the laboratory.
(4 marks)
iv) Using load versus deformation plots justify what you would expect to observe when carrying out a laboratory shear box test on both a loose and a very dense sand.
(3 marks)
Total 20 marks
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Page 12 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Question 6 i) A flexible foundation of length 4m and breadth 3m is to exert a uniform pressure of
150kN/m2 on the surface of an 8m layer of soil. Using Figure Q6a, determine the immediate settlement under the centre of the foundation if the elastic soil stiffness (E) is assumed to be 4MN/m2.
(6 marks)
ii) A flexible foundation of length 4m and breadth 3m is to exert a uniform pressure of 150kN/m2 on the surface of a layer of soil of assumed infinite thickness. Using Figure Q6b, determine the total stress at a depth of 5m beneath the centre of the foundation.
(5 marks)
iii) The following results were obtained from an oedometer test on a specimen of saturated clay
Applied Stress (kN/m2)
0 25 50 100 200 400 800
Void Ratio 0.985 0.950 0.921 0.880 0.833 0.784 0.737
a) Determine the value of mv for an effective stress range from
35kN/m2 to 140kN/m2. (6 marks)
b) Calculate the consolidation settlement for a 6m thick layer of this clay, when
the effective stress changes from 35kN/m2 to 140kN/m2. (3 marks)
Total 20 marks
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Page 13 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Figure Q6a
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Page 14 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Fig Q6b
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Page 15 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Question 7
i) Explain the difference between ‘compaction’ and ‘consolidation’ using geotechnical terminology. You should in your explanation refer to void ratio, pore water pressure, total stress, effective stress and soil mineralogy along with any other parameters you deem relevant.
(6 marks)
ii) Using Figure Q7c determine the total stress, pore water pressure and effective
stress at each strata change and at the location of the water table and hence plot a graph to illustrate their variation with depth from ground surface to a depth of 14m below ground level. The water table is located at a depth of 5m below ground level within an 8m thick deposit of sandy gravel overlying 6m of clay.
(14 marks)
Total 20 marks
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Page 16 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Sandy Gravel Bulk Unit Weight = 18kN/m3 5m Saturated Unit Weight = 20kN/m3
Water Table
3m Clay
Bulk Unit Weight = 19kN/m3 6m Saturated Unit Weight = 21kN/m3
NOTE: Assume that Unit Weight of Water = 10kN/m3
Figure Q7c
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Page 17 of 17 School of Engineering BEng (Hons) Civil Engineering Semester Two Exam - 2015/2016 Ground and Water Studies 2 Module No: CIE5005
Formulae
I = qB . I Eu
e = H . (1 + eo) mv = e . (1)
H (1 + eo)
v = v' + u H = mv v
' H
v = q I
Tv = ( cv t ) / d
2
END OF PAPER