8/12/2019 ascife.27510.0001

1/22

8/12/2019 ascife.27510.0001

2/22

Externally

applied

total

stress

Flexible impermeable membrane

Pore

water

pressureu

u Saturated soil

8/12/2019 ascife.27510.0001

3/22

8/12/2019 ascife.27510.0001

4/22

X X

u

u

u

1

u u

u

u

p

p

A

u

u

(p/A u)A

u

A+

8/12/2019 ascife.27510.0001

5/22

8/12/2019 ascife.27510.0001

6/22

8/12/2019 ascife.27510.0001

7/22

D

Unit column

Total stresses Pore water

pressure

Effective

stresses

u

v (vu)

(hu)h

8/12/2019 ascife.27510.0001

8/22

Piezometers

Rapidlyconstructed

embankment

Ground

level

Water

level

t>> 0

t> 0

t= 0

t=

u/ w

8/12/2019 ascife.27510.0001

9/22

1

3 = 3

3

ua/ wub/ w

u/ w

(13)

+ 0

8/12/2019 ascife.27510.0001

10/22

8/12/2019 ascife.27510.0001

11/22

8/12/2019 ascife.27510.0001

12/22

96

576

496

96

336

416456

1116

1116

1036

416456

1586

1036

1586

3136

3216

3136

3136

3136

24

210

Gravel

Clay

Gravel

Clay

Gravel

Clay

Gravel

Clay

(u)u kPa

416

416

496416

496416

210

210

155

155

416456

202

4

4

0

Long term

Short term

336

8/12/2019 ascife.27510.0001

13/22

p

p = o

(u) = p

t = o

u = p

(u) = p

v =o

t = u = o

(u) = p+p

v >o

t > o

o

8/12/2019 ascife.27510.0001

14/22

p pp

u = o

(u) = p+p

t = o

u = p

(u) = p+p

v =o

t = u = o

(u) = p

v >o

t > o

p u

8/12/2019 ascife.27510.0001

15/22

8/12/2019 ascife.27510.0001

16/22

Original ground

water level for

static water

table

Final groundwater level for

steady seepage

Equipotential

line

p

hf

ho

End of excavation

pore water pressure

Depth of cut

Shear stress on slip

line through P

Time

Time

Time

Time

(a)

(b)

(c)

(d)

Porewaterpressure

h0

w

Effectivestress

atP

Factorofsafet

y

Rapid

construction

Pore pressure

dissipation

Pore pressure

equilibrium

hfw

atP

8/12/2019 ascife.27510.0001

17/22

Equilibrium

ground water

levelh

P

End of loading

piezometric level

8/12/2019 ascife.27510.0001

18/22

Height of fill

Shear stress on slip

line through P

Time

Time

Time

Time

(a)

(b)

(c)

(d)

Porewaterpressure

hw

Effectivestress

atP

Factorofsafety

Rapid

construction

Pore pressure

dissipation

Pore pressure

equilibrium

atP

8/12/2019 ascife.27510.0001

19/22

8/12/2019 ascife.27510.0001

20/22

8/12/2019 ascife.27510.0001

21/22

= 0c = su

8/12/2019 ascife.27510.0001

22/22