Desain fondasai dangkal
-
Upload
galuh-rahmadyarto -
Category
Documents
-
view
237 -
download
0
Transcript of Desain fondasai dangkal
-
7/23/2019 Desain fondasai dangkal
1/87
Teori KapasitasDukung Tanah
1
-
7/23/2019 Desain fondasai dangkal
2/87
2
Defnisi-defnisiThe bearing capacity is the limiting pressurethat the footing can support.
Foundation : Structure transmits loads to theunderlying ground (soil). Footing: Slab element that transmit load fromsuperstructure to ground
Embedment depth, D f : The depth belowthe ground surface where the base of the footingrests.
Bearing pressure(q) : The normal stressimpose by the footing on the supporting ground.(weight of superstructure + self weight of
-
7/23/2019 Desain fondasai dangkal
3/87
3
Defnisi-defnisi
-
7/23/2019 Desain fondasai dangkal
4/87
4
-
7/23/2019 Desain fondasai dangkal
5/87
Bearing Capacityailure
5
-
7/23/2019 Desain fondasai dangkal
6/87
Transcosna !rain
"le#ator Canada ($ct.%&' % % )
West side of foundation sank 24-ft
6
-
7/23/2019 Desain fondasai dangkal
7/87
Kegagalan KapasitasDukung
a) !eneral Shear ailure* eruntuhan geserumum, Tipe keruntuhanyang paling umum; terjadiumumnya pada tanah yang
kuat dan atuan b) -ocal Shear ailure
* eruntuhan geser lo al, Kondisi antara keruntuhan
umum dan keruntuhantum ukan
c) /unching Shear ailure* eruntuhan gesertumbu an, terjadi pada
pasir sangat lepas danlempung lunak
!
-
7/23/2019 Desain fondasai dangkal
8/87
"earing #apa$ity %ailure
&
eneral shear failure
!ocal shear failure
"unching shearfailure
-
7/23/2019 Desain fondasai dangkal
9/87
Bearing Capacity ailurein Sand
'
-
7/23/2019 Desain fondasai dangkal
10/87
a) !eneral Shear ailureb) -ocal Shear ailurec) /unching Shear ailure
1(
)oad *s Displa$ement +a,ter esi$. +1'!3/
-
7/23/2019 Desain fondasai dangkal
11/87
Komentar mengenaikeruntuhan geser
"iasanya hanya perlu menganalisis keruntuhankapasitas umum
Keruntuhan geser lokal dan 0pun$hing iasanyadapat diantisipasi pada analisis penurunansettlement
Keruntuhan ,ondasi dangkal umumnya merupakan
kegagalan penurunan settlement ; namun Keruntuhan kapasistas dukung harus dianalisismeskipun dalam prakteknya keruntuhan gesertidak le ih dominan dari kegagalan ataukeruntuhan aki at penurunan
11
-
7/23/2019 Desain fondasai dangkal
12/87
erkem angan Teori
Kapasitas Dukung Tanah plikasi dari metoda keseim angan atas a alnyadiusulkan oleh randtl pada analisis tum ukan pada suatumassa tipis logam
7etoda dari randtl8s di adopsi oleh Ter9aghi untuk analisisKapasitas dukung ,ondasi dangkal:
esi$. dan e erapa ilmuan lain memperdalam Teori asli
Ter9aghi8s dan menam ahkan e erapa ,aktor-,aktor untukanalisis ,ondasi dangkal yang le ih lengkap:
nalisis ,ondasi dangkal aik kapasitas dukung maupunpenurunan le ih dilengkapi dengan metoda numerik e:g:% analisys
12
-
7/23/2019 Desain fondasai dangkal
13/87
sumsi-asumsi 7etoda Ter9aghi
1: Kedalaman ,ondasi adalah kurang atausama dengan le arnya:
2: Tidak terjadi slip antara dasar ,ondasidengan tanahnya dasar ,ondasi kasar
3: Tanah di a ah ,ondasi homogen dansemi infnite
4: 7ohr-#oulom model erlaku padatanah
5: Keruntuhan geser umum adalah modekeruntuhan yang menentukan +Tapi
ukan satu-satunya mode keruntuhan/
13
-
7/23/2019 Desain fondasai dangkal
14/87
ssumptions ,or Ter9aghi8s7ethod6: "elum terjadi konsolidasi pada tanah
!: %ondasi relati, sangat rigid kakudi andingkan tanahnya
&: Tanah diatas dasar ,ondasi tidak memilikikekuatan gesar; hanya se agai e anmerata sur$harge load terhadap e anguling o*erturning load
': "e an yang ekerja adalah e an tekan danekerja *ertikal pada $entroid ,ondasinya
1(: Tidak ada e an momen yang ekerja 14
-
7/23/2019 Desain fondasai dangkal
15/87
%ailure
-
7/23/2019 Desain fondasai dangkal
16/87
%ailure
-
7/23/2019 Desain fondasai dangkal
17/87
%ailure
-
7/23/2019 Desain fondasai dangkal
18/87
=in$e Ter9aghi neglected the shear strength ofsoils between the ground surface and a depth D ,the shear sur,a$e stops at this depth and the o*erlyingsoil has een repla$ed ith the sur$harge pressure 9D :This approa$h is $onser*ati*e> and is part o, thereason ,or limiting the method to relati*ely shallo,oundations (D < B).
Ter9aghi de*eloped his theory ,or $ontinuous,oundations +i:e:> those ith a #ery large !#B ratio ).
This is the simplest $ase e$ause it is a t o-dimensional pro lem .
?e then e@tended it to sAuare and round ,oundationsy adding empiri$al $oeB$ients o tained ,rom model
tests and produ$ed the ,ollo ing earing $apa$ity,ormulasC
1&
-
7/23/2019 Desain fondasai dangkal
19/87
or s0uare foundations:
or continuousfoundations:
or circular foundations BN N N cq q zDcult ++= 3.03.1
BN N N cq q zDcult ++= 5.0
N B N N cq q zDcult ++= 4.03.1
1'
-
7/23/2019 Desain fondasai dangkal
20/87
2(
-
7/23/2019 Desain fondasai dangkal
21/87
"e$ause o, the shape o, the ,ailure sur,a$e> the#alues of c and only need to represent thesoil between the bottom of the footing anda depth B below the bottom . The soils
et een the ground sur,a$e and a depth D aretreated simply as o*er urden .
Ter9aghi8s ,ormulas are presented in terms o,e e$ti*e stresses: 1owe#er > they also may eused in a total stress analyses y su stituting c T T and D for c', ', and D If saturated undrained$onditions e@ist> e may $ondu$t a total stress
analysis with the shear strength de ned asc T $ % u and T $ &. 2n this case , ' c $ . , ' q $*.+, and ' $ +.+.
The Ter9aghi earing $apa$ity ,a$tors areC 21
-
7/23/2019 Desain fondasai dangkal
22/87
( )
=
>
=
==
=
+=
1cos2
tan
0tan
1
07.5
)2/45(cos2
2
tan360/75.0
2
2
p
qc
c
q
K N
for N
N
for N
ea
a N
#ontdE
22
-
7/23/2019 Desain fondasai dangkal
23/87
23
-
7/23/2019 Desain fondasai dangkal
24/87
24
-
7/23/2019 Desain fondasai dangkal
25/87
Fntuk ,ondasi yang menunjukkan indi asi
eruntuhan geser lo al pada tanahnya> Ter9aghimenyarankan menggunakan rumus-rumus erikutuntuk menghitung kapasitas C
Dari "raja m: das
25
-
7/23/2019 Desain fondasai dangkal
26/87
Dari "raja m: das
26
-
7/23/2019 Desain fondasai dangkal
27/87
% #TGH G% = % TI
FS
qq
FS q
q
unet net all
uall
)()( =
=
JhereC
Au ultimate earing $apa$ity o, shallo ,oundation
Aall allo a le earing $apa$ity o, shallo ,oundation
Anet+u/ net ultimate earing $apa$ity o, shallo ,oundation
Aall net allo a le earing $apa$ity o, shallo ,oundation
%= %a$tor o, =a,ety +%= 3/
f
uunet
Dq
qqq
.)(
==
2!
-
7/23/2019 Desain fondasai dangkal
28/87
Lotes on Ter9aghi8s
7ethod#atatan untuk 7etoda Ter9aghi Karena kohesi tanah sulit untuk ditentukan>maka nilai $ohesi $ yang konser*ati,se aiknya digunakan
Kekuatan ,riksi nilai M le ih dapatdiandalkan dan tidak perlu diam il nilai yangkonser*ati, seperti nilai $
7etoda Ter9aghi simple dan umum digunakanoleh praktisi geoteknik; tapi metoda ini elummempertim angkan anyak ,aktor: 2&
-
7/23/2019 Desain fondasai dangkal
29/87
2'
-
7/23/2019 Desain fondasai dangkal
30/87
3(
-
7/23/2019 Desain fondasai dangkal
31/87
urther 3e#elopments
=kempton +1'51/ 7eyerho, +1'53/ "rin$h ?anson +1'61/ De "eer and )adanyi+1'61/ 7eyerho, +1'63/ "rin$h ?anson +1'!(/ esi$ +1'!3> 1'!5/ 31
-
7/23/2019 Desain fondasai dangkal
32/87
Auation:7ayerho, 7ethod ith $om ination o, ?ansen and
esi$ ,a$torsN
32
-
7/23/2019 Desain fondasai dangkal
33/87
33
)1)tan(1.4(N N1)cot(N N
/2)(45tane N
q
qc
2tanq
= =
+=
-
7/23/2019 Desain fondasai dangkal
34/87
The
-
7/23/2019 Desain fondasai dangkal
35/87
The
-
7/23/2019 Desain fondasai dangkal
36/87
Gther %a$tors
36
Gth % $t ? d
-
7/23/2019 Desain fondasai dangkal
37/87
Gther %a$tors ,rom ?ansen andesi$
3!
O %or $ontinuous,ooting>s 1
O %or perpendi$ularload> i 1O %or le*el ,oundation> 1O %or le*el ground>
g 1O Leed to $ompute,a$tors
- "earing #apa$ity %a$tor L> - Depth %a$tor d
-
7/23/2019 Desain fondasai dangkal
38/87
!round water "4ects
3&
-
7/23/2019 Desain fondasai dangkal
39/87
-
7/23/2019 Desain fondasai dangkal
40/87
4(
e$ts
-
7/23/2019 Desain fondasai dangkal
41/87
$$T26!S 72T1"CC"6T52C$5 26C-26"3 -$8326!S
41
$$entri$ity
2nclination
$$T26!S 72T1 $ne 7ay
-
7/23/2019 Desain fondasai dangkal
42/87
$$T26!S 72T1 $ne 7ay "ccentricity Pn most instan$es> ,oundations are su je$ted to moments in
addition to the #ertical load as sho n elo : Pn su$h $ases thedistri ution o, pressure y the ,oundation upon the soil is not uniform :
42
-
7/23/2019 Desain fondasai dangkal
43/87
43
-
7/23/2019 Desain fondasai dangkal
44/87
44
$$T26!S 72T1 $ne 7ay
-
7/23/2019 Desain fondasai dangkal
45/87
Lote that in these eAuations> hen the e$$entri$ity e e$omes B9 ' q min is ;ero :
%or e < B9 >q min ill e negati#e > hi$h means thattension ill de*elop: *not good===,
"e$ause soils $an sustain *ery little tension> there ille a separation et een the ,ooting and the soil under
it: lso note that the eccentricity tends to decrease
the load bearing capacity o, a ,oundation: Pn su$h $ases> pla$ing ,oundation $olumn o -$enter> as
sho n in %igure is pro a ly ad*antageous: Doing so in e e$t> produ$es a $entrally loaded
,oundation ith a uni,ormly distri uted pressure:45
$$T26!S 72T1 $ne 7ay "ccentricity
$$T26!S 72T1 $ne 7ay
-
7/23/2019 Desain fondasai dangkal
46/87
46
$$T26!S 72T1 $ne 7ay "ccentricity
ti g ith T >
-
7/23/2019 Desain fondasai dangkal
47/87
ooting with Two>way"ccentricities#onsider a ,ooting su je$t to a #ertical ultimate load ? ult and a
moment @ as sho n in %igures a and : %or this $ase> the $omponents
o, the moment @ a out the @ and y a@is are @ A and @ y respe$ti*ely: This$ondition is eAui*alent to a load Q pla$ed e$$entri$ally on the ,ooting
ith A eB and y e- as sho n in %igure d:
4!
ti g ith T >
-
7/23/2019 Desain fondasai dangkal
48/87
4&
ooting with Two>way"ccentricities
T7$>78 "CC"6T52C2T D C8S" %
-
7/23/2019 Desain fondasai dangkal
49/87
T7$>78 CC 6T52C2T D C8S %
4'
4'
T7$>78 "CC"6T52C2T D C8S" E
-
7/23/2019 Desain fondasai dangkal
50/87
T7$>78 CC 6T52C2T D C8S E
5(
5(
T7$>78 "CC"6T52C2T D C8S"
-
7/23/2019 Desain fondasai dangkal
51/87
T7$>78 CC 6T52C2T D C8S
51
51
T7$>78 "CC"6T52C2T D C8S"
-
7/23/2019 Desain fondasai dangkal
52/87
T7$>78 CC 6T52C2T D C8S
52
52
T7$>78 "CC"6T52C2T D C8S" F
-
7/23/2019 Desain fondasai dangkal
53/87
T7$>78 CC 6T52C2T D C8S F
53
53
TJG-J I ## LTHP#PTI R # = 4
-
7/23/2019 Desain fondasai dangkal
54/87
TJG-J I ## LTHP#PTI R # = 4
54
TJG-J I ## LTHP#PTI R # = 5
-
7/23/2019 Desain fondasai dangkal
55/87
TJG J I ## LTHP#PTI R # 5
55
55
"A l %
-
7/23/2019 Desain fondasai dangkal
56/87
"Aample %
56
"A l %
-
7/23/2019 Desain fondasai dangkal
57/87
5!
"Aample %
"A l E
-
7/23/2019 Desain fondasai dangkal
58/87
5&
"Aample E
-
7/23/2019 Desain fondasai dangkal
59/87
5'
"Aampl
e E
-
7/23/2019 Desain fondasai dangkal
60/87
ootings with 2nclined-oads
6(
ootings with 2nclined
-
7/23/2019 Desain fondasai dangkal
61/87
1: #ompute the in$lination ,a$tors using the eAuationsgi*en elo C
in$lination o, load ith respe$t to *erti$al
2: Fse the in$lination ,a$tors just $omputed to $ompute?ansen shape ,a$tors as
61
ootings with 2nclined-oads
ootings with 2nclined
-
7/23/2019 Desain fondasai dangkal
62/87
3: These are used in the ,ollo ing modif$ations o, the
Sedited0 ?ansen earing $apa$ity eAuationC
Fse the smaller #alue of q ult $omputed y either o,Auations:
62
ootings with 2nclined-oads
-
7/23/2019 Desain fondasai dangkal
63/87
The Bearing Capacity
of @ulti>-ayered Soils
63
The Bearing Capacity of -ayered
-
7/23/2019 Desain fondasai dangkal
64/87
g p y ySoils
64
The Bearing Capacity of -ayered
-
7/23/2019 Desain fondasai dangkal
65/87
Pn layered soil profles> the unit weight o, the soil> the angleof friction and the cohesion are not constant throughout
the depth: The ultimate sur,a$e ,ailure may e@tend throught o or more o, the soil layers:
Consider the case when the stronger soil is underlainby a wea er soil : P, 1 > the thi$kness o, the layer o, soil elo
the ,ooting> is relati#ely large then the ,ailure sur,a$e ill e$ompletely lo$ated in the top soil layer> hi$h is the upperlimit ,or the ultimate earing $apa$ity:
P, the thi$kness 1 is small $ompared to the ,oundation idth
B> a punching shear failure will occur at the top soilstratum> ,ollo ed y a general shear ,ailure in the ottom soillayer:
P, 1 is relati#ely deep > then the shear ,ailure ill o$$ur only
on the top soil layer:
65
g p y ySoils
The Bearing Capacity of -ayered
-
7/23/2019 Desain fondasai dangkal
66/87
7eyerho, and ?anna +1'!&/ and 7eyerho,+1'!4/
66
The Bearing Capacity of ayeredSoils
-
7/23/2019 Desain fondasai dangkal
67/87
6!
-
7/23/2019 Desain fondasai dangkal
68/87
6&
-
7/23/2019 Desain fondasai dangkal
69/87
6'
-
7/23/2019 Desain fondasai dangkal
70/87
!(
-
7/23/2019 Desain fondasai dangkal
71/87
!1
-
7/23/2019 Desain fondasai dangkal
72/87
7eyerho, and
?annas pun$hingshear $oeB$ient K s
!2
The "earing #apa$ity o )ayered
-
7/23/2019 Desain fondasai dangkal
73/87
The earing #apa$ity o, )ayered=oils
ariation o,
c a c 1 ith
q 2 q 1ased on thetheory o,
7eyerho, and?anna +1'!&/ !3
"Aample on layered soils
-
7/23/2019 Desain fondasai dangkal
74/87
!4
-
7/23/2019 Desain fondasai dangkal
75/87
@ample on layered soils
!5
-
7/23/2019 Desain fondasai dangkal
76/87
@ample on layered soils
!6
! d t
-
7/23/2019 Desain fondasai dangkal
77/87
!round actors
!!
B t
-
7/23/2019 Desain fondasai dangkal
78/87
Base actor
%or ,ootings ith angled ,oundation ases Jhen ,ooting is le*el> 1
!&
5igidi
-
7/23/2019 Desain fondasai dangkal
79/87
!'
gty
actors
-
7/23/2019 Desain fondasai dangkal
80/87
Bearing Capacity from ield Tests
&(
Bearing Capacity from
-
7/23/2019 Desain fondasai dangkal
81/87
Bearing Capacity fromS/T
&1
Bearing Capacity from
-
7/23/2019 Desain fondasai dangkal
82/87
&2
Bearing Capacity fromS/T
Bearing Capacity from
-
7/23/2019 Desain fondasai dangkal
83/87
&3
Bearing Capacity fromS/T
Bearing Capacity
-
7/23/2019 Desain fondasai dangkal
84/87
Bearing Capacityusing C/T
&4
Bearing Capacity for ield
-
7/23/2019 Desain fondasai dangkal
85/87
Bearing Capacity for ield-oad Tests /-T
&5
Bearing Capacity for ield -oad
-
7/23/2019 Desain fondasai dangkal
86/87
g p yTests /-T
%or
-
7/23/2019 Desain fondasai dangkal
87/87
penetration number Pt has een suggested that the = T e standardi9ed to
some energy ratio Er hi$h should e $omputed as
Lote that larger *alues o, Er decrease the lo $ount Nnearly linearly> that is> Er45 gi*es N = 20 and Er90 gi*es L 1(;
@ample o, N ,or Er45 = 2( e o tain ,or the ar itrarily$hosen Er = !(> + Er70 /C
&!