Ch. 16 Retaining Structures

Transcription

1 Ch Retaining Structures Page 1 Ch. 16 Retaining Structures Reading Assignment Salgado Ch. 16 Lecture Notes Homework Assignment 1. Develop a spreadsheet for the design of an embedded gravity wall (see example in class notes.) Turn in your solution for the case given in the lecture notes 2. Determine the factor of safety against overturning and sliding for the following case: Wall Dimensions Fill Properties Top 4 ft β backfill deg radians Bottom 4 ft β toe deg radians γ concrete 150 pcf φ deg radians H 15 ft δ deg radians D 3 ft Q backwall deg radians Partial Answer Factors of Safety FS sliding FS oturn Q frontwall deg radians γ backfill 120 pcf 3. Determine the factor of safety against overturning and sliding for the following case: Wall Dimensions Fill Properties Top 3 ft β backfill deg radians Bottom 3 ft β toe deg radians γ concrete 150 pcf φ deg radians H 10 ft δ deg radians D 0 ft Q backwall deg radians Q frontwall deg radians γ backfill 120 pcf

2 Ch Retaining Structures Page 2 Introduction to Retaining Structures Failure modes (a) bearing capacity failure of base or footing (b) sliding (c) overturning (d) global instability

3 Ch Retaining Structures Page 3 Introduction to Retaining Structures (cont.) (a) bearing capacity failure This failure was due to liquefaction of the foundation soils 2010 Chilean earthquake

4 Ch Retaining Structures Page 4 Introduction to Retaining Structures (cont.) (b) sliding roberts.co.uk/photo/pmisc0.jpg

5 Ch Retaining Structures Page 5 Introduction to Retaining Structures (cont.) (c) overturning and build gallery/

6 Ch Retaining Structures Page 6 Introduction to Retaining Structures (cont.) (d) global instability

7 Ch Retaining Structures Page 7 Introduction to Retaining Structures (cont.) Remediation of MSE wall failure Woodlands Building C, Philippines

8 Ch Retaining Structures Page 8 Introduction to Retaining Structures (cont.) Remediation of MSE wall failure Woodlands Building C, Philippines Final configuration without EPS Geofoam

9 Ch Retaining Structures Page 9 Earth Pressure Theory Which Theory? K = ' h / ' v

10 Ch Retaining Structures Page 10 Earth Pressure Theory, Ko Conditions ' '

11 Ch Retaining Structures Page 11 Earth Pressure Theory, Ko Conditions (cont.)

12 Ch Retaining Structures Page 12 Earth Pressure Theory, Ko Conditions (cont.)

13 Ch Retaining Structures Page 13 Earth Pressure Theory, Ko Conditions (cont.)

14 Ch Retaining Structures Page 14 Earth Pressure Theory, Ko Conditions (cont.)

15 Ch Retaining Structures Page 15 Earth Pressure Theory, Active State

16 Ch Retaining Structures Page 16 Earth Pressure Theory, Active State (cont.)

17 Ch Retaining Structures Page 17 Earth Pressure Theory, Active State (cont.)

18 Ch Retaining Structures Page 18 Earth Pressure Theory, Active State (cont.)

19 Ch Retaining Structures Page 19 Active Failure State Pressure Diagrams For sliding For toppling Earth pressure diagram Earth pressure diagram for the active case (for case without water in backfill).

20 Ch Retaining Structures Page 20 Active Failure State Pressure Diagrams (cont.) For sliding For toppling Earth pressure diagram Hydrostatic water pressure diagram Earth pressure diagram for the active case (for case with water)

21 Ch Retaining Structures Page 21 Active Failure State Sloped Backfill Force diagram E A is unknown. Maximize E A by solving for de A / d = 0 For more information, see Coulomb Theory

22 Ch Retaining Structures Page 22 Earth Pressure Theory, Passive State

23 Ch Retaining Structures Page 23 Earth Pressure Theory, Passive State (cont.)

24 Ch Retaining Structures Page 24 Earth Pressure Theory, Passive State (cont.)

25 Ch Retaining Structures Page 25 Earth Pressure Theory More Pressure Diagrams

26 Ch Retaining Structures Page 26 Earth Pressure Theory More Pressure Diagrams (cont.)

27 Ch Retaining Structures Page 27 Earth Pressure Theory More Pressure Diagrams (cont.)

28 Ch Retaining Structures Page 28 Earth Pressure Theory More Pressure Diagrams (cont.)

29 Ch Retaining Structures Page 29 Earth Pressure Theory More Pressure Diagrams (cont.)

30 Ch Retaining Structures Page 30 Earth Pressure Theory, Coulomb Theory Active State

31 Ch Retaining Structures Page 31 Earth Pressure Theory, Coulomb Theory Active State (cont.)

32 Ch Retaining Structures Page 32 Earth Pressure Theory, Coulomb Theory Active and Passive State Kp equation from Das, Principles of Geotechnical Engineering 4th Edition. I have corrected the error in this equation.

33 Ch Retaining Structures Page 33 Earth Pressure Theory, Coulomb Theory Active and Passive State The notation in this table is different from that used in the free body diagrams in the previous pages. For this table, ALPHA) is the inclination of the backwall measured from the horizontal (i.e., is 90 for a vertical backwall); BETA) is the inclination of the slope behind the wall, (phi) is the internal angle of friction of the backfill soil, and (delta) is the interface friction between the backfill soil and the wall (i.e., concrete). The values in this table can be used to check your functions entered in the homework spreadsheet.

34 Ch Retaining Structures Page 34 Earth Pressure Theory, Rankine Approximation for Sloped Backfill

35 Ch Retaining Structures Page 35 Active and Passive Pressure Movement of Wall Note that the amount of lateral displacement wlat is much larger for the passive state e when compare with that of active state. This means that full active earth pressure is mobilized after only small displacements; whereas full passive earth pressure requires more displacement. Hence, especially for passive earth pressure, one must consider the amount of displacement that is expected in order to estimate the passive earth pressure.

36 Ch Retaining Structures Page 36 Active and Passive Pressure Application in Wall Design

37 Ch Retaining Structures Page 37 Retaining Wall Design (Free Body Diagrams Gravity Wall)

38 Ch Retaining Structures Page 38 Retaining Wall Design (Gravity Wall Spreadsheet) Tuesday, December 5, :49 AM

39 Ch Retaining Structures Page 39 Retaining Wall Design ( FBD Cantilevered Wall) For more information on the design of cantilevered wall systems, see handout on course website

40 Ch Retaining Structures Page 40 Retaining Wall Design ( FBD Cantilevered Wall with Tieback)

41 Ch Retaining Structures Page 41 Retaining Wall Design (Mechanically Stabilized Earth Walls ( MSE))

42 Ch Retaining Structures Page 42 Soil Nailing

43 Ch Retaining Structures Page 43 Soil Nailing Remediation of a MSE wall using soil nailing Soil nailing Provo Canyon To stabilize a potential landslide, which could be triggered by a cut for the new roadway alignment, Schnabel Foundation Company installed 208 encapsulated 14 strand anchors in the sidehill cut. The anchors have a design load of 400 kips and an average installed length of 160 feet in order to make capacity behind the failure plain From <

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