Homework Help is Here – Start Your Trial Now!
Engineering
Civil Engineering
Exercise Figure 8.1 20 ft 220 ft -200 ft- 8.1). The concrete has a unit weight of 2.4 Mg/m³ (150 lb/ft³). The height of the dam is 67.1 m (220 ft), the crest is 6.1 m (20 ft) wide, and the base is 61 m (200 ft) wide. Note: 1 ft = 0.3048 m. a. What is the average pressure exerted on the rock foundation in MPa (lb/ft2)? What is the maximum pressure? Explain. b. Refer to the different sedimentary rocks listed in Table 8.1. Using average compressive strength and shear strength values for these sedimentary rocks compare them to the average pressure calculated in part (a). Are any so low to be of concern? Explain. c. Assume that the pressure from the weight of the dam is dissipated within 30.3 m (100 ft) below the rock surface and the full pressure acts over this distance. How much settlement will occur in the center of the dam because of the gravity force for the different sedimentary rocks listed in Table 8.1 (use average values)? Ind

Exercise Figure 8.1 20 ft 220 ft -200 ft- 8.1). The concrete has a unit weight of 2.4 Mg/m³ (150 lb/ft³). The height of the dam is 67.1 m (220 ft), the crest is 6.1 m (20 ft) wide, and the base is 61 m (200 ft) wide. Note: 1 ft = 0.3048 m. a. What is the average pressure exerted on the rock foundation in MPa (lb/ft2)? What is the maximum pressure? Explain. b. Refer to the different sedimentary rocks listed in Table 8.1. Using average compressive strength and shear strength values for these sedimentary rocks compare them to the average pressure calculated in part (a). Are any so low to be of concern? Explain. c. Assume that the pressure from the weight of the dam is dissipated within 30.3 m (100 ft) below the rock surface and the full pressure acts over this distance. How much settlement will occur in the center of the dam because of the gravity force for the different sedimentary rocks listed in Table 8.1 (use average values)? Ind

Structural Analysis
Structural Analysis
6th Edition
ISBN:9781337630931
Author:KASSIMALI, Aslam.
Publisher:KASSIMALI, Aslam.
Chapter2: Loads On Structures
Section: Chapter Questions
Problem 1P
See similar textbooks
icon
Related questions
Question
100%
8.1
20 ft 220 ft -200 ft- Exercise Figure 8.1 8.1). The concrete has a unit weight of 2.4 Mg/m³ (150 lb/ft³). The height of the dam is 67.1 m (220 ft), the crest is 6.1 m (20 ft) wide, and the base is 61 m (200 ft) wide. Note: 1 ft = 0.3048 m. a. What is the average pressure exerted on the rock foundation in MPa (lb/ft2)? What is the maximum pressure? Explain. b. Refer to the different sedimentary rocks listed in Table 8.1. Using average compressive strength and shear strength values for these sedimentary rocks compare them to the average pressure calculated in part (a). Are any so low to be of concern? Explain. c. Assume that the pressure from the weight of the dam is dissipated within 30.3 m (100 ft) below the rock surface and the full pressure acts over this distance. How much settlement will occur in the center of the dam because of the gravity force for the different sedimentary rocks listed in Table 8.1 (use average values)? 7. Excavation for a gravity dam foundation revealed a unit of poorly cemented sandstone 30.3 m (100 ft) wide (plan view) within a massive dolomite sequence. The dolomite has an E value of 5.5 x 104 MPa (8 x 106 psi) and the sandstone has an E value of 6.9 x 10³ MPa (1 x 106 psi). a. What would be the concern if both rocks were loaded equally by the gravity dam? What would be the effect on the dam? b. How could this problem be alleviated? Consider both replacement and strengthening possibilities. 8. A 333.3-m (1100-ft) long, horseshoe-shaped tunnel is to be driven through massive granite with a unit weight of 2.72 Mg/m³ (170 lb/ft3). The tunnel is 9.1 m (30 ft) high and 9.1 m (30 ft) wide in cross section (Exercise Figure 8.2). The maximum rock cover above the tunnel in the middle of the mountain is 366.5 m (1200 ft). Note: 1 ft = 0.3048 m. 15 ft -30 ft- Exercise Figure 8.2 a. What is the total overburden stress at the midway point in the tunnel in MPa (psi and psf)? b. Because of arching effects that transfer load around the tunnel opening, the roof or crown of the tunnel does not commonly support the full overburden stress, but instead is typically much less. If the roof stress was found to be 0.12 MPa (2500 psf), how many meters (feet) of rock above the tunnel does this represent? How do you suppose this load would be supported in the tunnel? ant to s c. If the tunnel excavation was completed in 80 work- ing days with two shifts per day, how many lineal meters (feet) of tunnel were excavated per day? How many meters (feet) per shift? What was the average volume of rock removed per day, per shift? (Hint: Calculate the area of the cross section.) As d. The tunnel project was bid at $1,878,000. What would be the cost per lineal foot of the tunnel? Right abutment 9. An arch dam transfers much of the water load onto the abutments (the rock mass on the sides of the dam) (see Exercise Figure 8.3 for a plan view). The E value for the concrete is 4.14 x 104 MPa (6 x 106 psi). Exercise Figure 8.3 a. What would occur if the abutments were shale with an E of 2.07 x 104 (3 x 106 psi)? b. What if the abutments were diabase with an E of 9.66 x 104 MPa (14 x 106 psi)? Which of the two rocks would be preferred, the shale or the diabase? Explain why. Upstream Downstream /Left abutment
Transcribed Image Text:20 ft 220 ft -200 ft- Exercise Figure 8.1 8.1). The concrete has a unit weight of 2.4 Mg/m³ (150 lb/ft³). The height of the dam is 67.1 m (220 ft), the crest is 6.1 m (20 ft) wide, and the base is 61 m (200 ft) wide. Note: 1 ft = 0.3048 m. a. What is the average pressure exerted on the rock foundation in MPa (lb/ft2)? What is the maximum pressure? Explain. b. Refer to the different sedimentary rocks listed in Table 8.1. Using average compressive strength and shear strength values for these sedimentary rocks compare them to the average pressure calculated in part (a). Are any so low to be of concern? Explain. c. Assume that the pressure from the weight of the dam is dissipated within 30.3 m (100 ft) below the rock surface and the full pressure acts over this distance. How much settlement will occur in the center of the dam because of the gravity force for the different sedimentary rocks listed in Table 8.1 (use average values)? 7. Excavation for a gravity dam foundation revealed a unit of poorly cemented sandstone 30.3 m (100 ft) wide (plan view) within a massive dolomite sequence. The dolomite has an E value of 5.5 x 104 MPa (8 x 106 psi) and the sandstone has an E value of 6.9 x 10³ MPa (1 x 106 psi). a. What would be the concern if both rocks were loaded equally by the gravity dam? What would be the effect on the dam? b. How could this problem be alleviated? Consider both replacement and strengthening possibilities. 8. A 333.3-m (1100-ft) long, horseshoe-shaped tunnel is to be driven through massive granite with a unit weight of 2.72 Mg/m³ (170 lb/ft3). The tunnel is 9.1 m (30 ft) high and 9.1 m (30 ft) wide in cross section (Exercise Figure 8.2). The maximum rock cover above the tunnel in the middle of the mountain is 366.5 m (1200 ft). Note: 1 ft = 0.3048 m. 15 ft -30 ft- Exercise Figure 8.2 a. What is the total overburden stress at the midway point in the tunnel in MPa (psi and psf)? b. Because of arching effects that transfer load around the tunnel opening, the roof or crown of the tunnel does not commonly support the full overburden stress, but instead is typically much less. If the roof stress was found to be 0.12 MPa (2500 psf), how many meters (feet) of rock above the tunnel does this represent? How do you suppose this load would be supported in the tunnel? ant to s c. If the tunnel excavation was completed in 80 work- ing days with two shifts per day, how many lineal meters (feet) of tunnel were excavated per day? How many meters (feet) per shift? What was the average volume of rock removed per day, per shift? (Hint: Calculate the area of the cross section.) As d. The tunnel project was bid at $1,878,000. What would be the cost per lineal foot of the tunnel? Right abutment 9. An arch dam transfers much of the water load onto the abutments (the rock mass on the sides of the dam) (see Exercise Figure 8.3 for a plan view). The E value for the concrete is 4.14 x 104 MPa (6 x 106 psi). Exercise Figure 8.3 a. What would occur if the abutments were shale with an E of 2.07 x 104 (3 x 106 psi)? b. What if the abutments were diabase with an E of 9.66 x 104 MPa (14 x 106 psi)? Which of the two rocks would be preferred, the shale or the diabase? Explain why. Upstream Downstream /Left abutment
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 3 steps with 3 images

SEE SOLUTIONCheck out a sample Q&A here
Blurred answer
Knowledge Booster
Pressurized pipe flow
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, civil-engineering and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Structural Analysis
Structural Analysis
Civil Engineering
ISBN:
9781337630931
Author:
KASSIMALI, Aslam.
Publisher:
Cengage,
Structural Analysis (10th Edition)
Structural Analysis (10th Edition)
Civil Engineering
ISBN:
9780134610672
Author:
Russell C. Hibbeler
Publisher:
PEARSON
Principles of Foundation Engineering (MindTap Cou…
Principles of Foundation Engineering (MindTap Cou…
Civil Engineering
ISBN:
9781337705028
Author:
Braja M. Das, Nagaratnam Sivakugan
Publisher:
Cengage Learning
Fundamentals of Structural Analysis
Fundamentals of Structural Analysis
Civil Engineering
ISBN:
9780073398006
Author:
Kenneth M. Leet Emeritus, Chia-Ming Uang, Joel Lanning
Publisher:
McGraw-Hill Education
Sustainable Energy
Sustainable Energy
Civil Engineering
ISBN:
9781337551663
Author:
DUNLAP, Richard A.
Publisher:
Cengage,
Traffic and Highway Engineering
Traffic and Highway Engineering
Civil Engineering
ISBN:
9781305156241
Author:
Garber, Nicholas J.
Publisher:
Cengage Learning
SEE MORE TEXTBOOKS