Lec 1 Lateral Earth Pressure
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Transcript of Lec 1 Lateral Earth Pressure
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Geological Engineering
University of Wisconsin-Madison
GLE/CEE 330: Soil
Mechanics
Lateral Earth Pressure
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Learning Objectives
Learn about key concepts:
Place in context of Mor !ircle analysis
"t rest# active and passive eart pressure
Lateral eart pressure coefficients
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Lateral Earth Pressure
(R.P.
Weber)
(R.P.Weber)
?
?
?
?
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Water Pressure and Soil Pressure
Consider at-rest (geostatic)
condition
Consider hydrostatic
condition
Anisotropic
x
z
z
x
z
x>
Isotropic
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Earth Pressure Coeicient !"t #est$
x
z
K0= Coefcient o atera! "arth
#ress$re at %est
&or nor'a!!y conso!idated soi! (ay*
+,).
&or o/erconso!idated soi! (eyerho1*
+,23).
In
genera!.
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Ca!c$!ate !atera! tota! stress (x) at z = 4
' i K0= 054
x
(M.
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Active and Passive Limit Conditions
Ka= Coefficient of Active Earth Pressure
(Wall Moving Away from Backfill)
(small s)
Active Failure Condition
movement Active
!ailure
We"ge(#$%/&)
K'= Coefficient of Passive Earth Pressure
(Wall Moving owar" Backfill)
(large s)
Passive Failure Condition
movementPassive
!ailure
We"ge
(#$ *&)
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movement
Passive !ailure
Consi"er Mohr+s Circles, s"ecreases until failure
sincreases until failure
movement
Active
!ailure
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=
+
=
+
=
2
'45tan
'sin1
'sin1
..
'sin1
'sin1''
2
a
xz
K
so
#o!e
#oint
Acti/e
&ai!$re
4 67
4 6
7
%anine Acti/e &ai!$re 8$race
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#o!e
#oint
%anine #assi/e &ai!$re 8$race
+=
+
=
+
=
2
'45tan
'sin1
'sin1
..
'sin1
'sin1''
2
p
zx
K
so
4
67
#assi/e
&ai!$re
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"/o!$tion o !atera! stress 9ith 9a!! 'o/e'ent:
Acti/e &ai!$re at
Ka
#assi/e &ai!$re at
Kp
8tationary (at
rest)
o/e'ent
to9ard
;ac
o/e'ent a9ay
ro' ;ac
Ka K0 Kp
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Essential Points+) Coefcient o atera! "arth
#ress$re at %est
7) Acti/e "arth #ress$re Coefcient.
>) #assi/e "arth #ress$re
Coefcient.
) Acti/e s!ip p!anes at 4 @67 to
horizonta!4) #assi/e s!ip p!anes at 4 -67 to
horizonta!3) ore 9a!! 'o/e'ent (in9ard) reB$ired or passi/e ai!$re than
acti/e (o$t9ard) ai!$re
