Ch23 - Retaining wall Figures

8/8/2019 Ch23 - Retaining wall Figures

1/21

SlidingFriction

PassivePressure

Active pressure

Figure 23.1 Forces and pressures acting between an earth retaining structure and the ad- jacent ground.


2/21

WallBackfill

b

At-restlateralearth pressure

K 0 H

H

Figure 23.2 At-rest pressure acting on a retaining wall.


3/21

Active Condition

At-Rest Condition

FailurePlane

'

c

' z ' x ' x

AB

FailurePlane

Figure 23.3 Changes in the stress conditions in a soil as it transitions from the at-restcondition to the active condition.


4/21

Movement

Shear-failurePlanes

45 + /2

Figure 23.4 Development of shear failureplanes in the soil behind a wall as it transi-tions from the at-rest condition to the activeconditon.


5/21

Movement Awayfrom B ackfill

Movement Toward Backfill0

K p

K a

K o

C o e

f f i c i e n

t o

f L a

t e r a

l E a r t

h P r e s s u r e

Figure 23.5 Effect of wall movement onlateral earth pressure in sand.


6/21


7/21

' z ' x ' x

A

B

FailurePlane

PassiveCondition

c

'

At-RestCondition

FailurePlane

Figure 23.7 Changes in the stress condi-tion in a soil as it transitions from the at-restcondition to the passive condition.


8/21

Active Pressure

SlidingFriction

PassivePressure

Figure 23.8 Active and passive pressures acting on a cantilever retaining wall.


9/21

45 /2

W / b

T / b

N / b

V p / b

P p / b

(a)

(b)

H

45 + /2

W / b

T / b

N / b

V a / bP a / b

H

Figure 23.9 Free body diagram of soil behind a retaining wall using Rankine s solution:(a) active case; and (b) passive case.


10/21

(a) (b)

Figure 23.10 Comparison between (a) the-oretical and (b) observed distributions of earth pressures acting behind retaining struc-tures.


11/21

13

44 kN/m

136 kN/m

6 m

Figure 23.11 Results from Example 23.2.


12/21

V a / b

H

wP a / b

Figure 23.12 Parameters for Coulomb s active earth pressure equation. Walls inclinedin the opposite direction have a negative . V a /b normally acts in the direction shown,

thus producing a positive w .


13/21

12

c = 0 = 32

= 19.8 kN/m 3

5.60 m2

Figure 23.13 Retaining wall for Example 23.4.


14/21

H

H c

Figure 23.14 Theoretical active pressuredistribution in soils with cohesion ( c 0,

0).


15/21

H

Figure 23.15 Theoretical distribution of passive earth pressure in soils with cohesion(c 0, 0).


16/21

80

60

40

20

0

160

140

120

100

80

60

40

20

0

0

5

10

25

20

15

10

5

010 20 30

5 Gv

(kN/m3)

6 : 1 3 : 1 2 : 1 1 : 112

2 :1 max.

3 :1 max.

2 :1 max.

Slope Angle

Gv

(lb/ft3) H

H

3

2

1

4

5

4

1

3 2

G h(kN/m 3)

G h(lb/ft 3)

40

Figure 23.16 Charts for estimating the loads acting against a retaining wall beneath a planarground surface (Adapted from Terzaghi and Peck, 1967).


17/21

H 1

H 1 = 0

Soil Type 1 Soil Type 2 Soil Type 3

Gv = 0

Slope 1 12 : 1

Slope 1 12 : 1Slope 1 12 : 1

3 :16 :1

3 :1

6 :1

34 : 11

12 : 11

H 1 / H

160

140

120

100

80

60

40

20

0 0.2 0.4 0.6 0.8 1.0

0 0.2 0.4 0.6 0.8 1.0

G(lb/ft) 3

0 0.2 0.4 0.6 0.8 1.0

25

20

15

10

5

0

0 0.2 0.4 0.6 0.8 1.0

80

100

60

40

20

Soil Type 4 Soil Type 5

H 1 / H

G(lb/ft) 3

G(kN/m 3)

G(kN/m 3)

15

10

5

0

H

H

H 1

H

0 0.2 0.4 0.6 0.8 1.0

Max Slope 2 : 1

Max Slope 3 : 1Max Slope 2 : 1

12 : 111

2 : 1134 : 1134 : 11

2 :13 :1 2 :1

3 :12 :1 2 :1

3 :1

34 : 11 2 :1 3 :1

6 :1

34 : 11

2 :13 :1

6 :16 :1

34 : 11 3 :12 :1

Legend

Gh

Gv

Figure 23.17 Charts for estimating the loads acting against a retaining wall below a ground surfacethat is sloped and then becomes level. For soil type 5, use an H value 4 ft (1 m) less than the actualheight (Adapted from Terzaghi and Peck, 1967).


18/21

Point LoadSurcharge

Uniform

Surcharge

Figure 23.18 Typical surcharge loads near a retaining wall.


19/21

q = 13.0 kPa2.5 m

(kPa)

= 31 = 0.3

c = 09.0 m

0 5 10 15 20

Due toUniformLoad Due to

Point Load

1

2

3

4

z

( m

)

1000 kN

Figure 23.19 Proposed retaining wall with surcharge load for Example 23.6.


20/21

Pressure due to Backfill(Lateral Earth Pressure)

Pressure due to Groundwater(Hydrostatic Pressure)

u

Figure 23.20 Theoretical lateral pressuredistribution with shallow groundwater table.


21/21

Groundwaterat b

b

Pressure due to Backfill Hydrostatic Pressure

Groundwaterat a

5.3 m

2.5 m

a

b

a

6 m

Figure 23.21 Retaining wall for Example 23.7.

Ch23 - Retaining wall Figures

Documents

Transcript of Ch23 - Retaining wall Figures