Phan tich mot so yeu to anh hirang den s y phan phoi tai trong giCpa coc va be cua giai phap mong be coc Analysing some factors affecting on the ratio load distribution between piles and total building load of piled raft foundations
Ngay nhan bai: 22/9/2014 Ngay su^ bai: 5/6/2015 Ngay chap nhan dang: 10/12/2015
T 6 M TAT
Nguyen tac thiet ke mdng hh cpc 1^ co xem xet d^n sii phSn phoi mpt phan cua t i i trong cua dng trinh cho nen dat nam tnic tiep difdi ban mong be. Mile dp phan phoi tai trpng dcTng cho cpc va cho dat dddii ban mdng cd th€ phy thupc v i o nhilu yeu t6 khdc nhau. Tac gia chu yeu sii dyng phan mem Plaxis 3D di xem xet mot s6 yeu td anh hudng d i n t^ 1^ phan phdi tai trpng cua cdng tiinh vao trong cac cpc ben diidi be so v6i tong tai trpng ciia cong trinh. PhUPng ph4p phSn tich dupe dung trong bai nay 1^ thay doi mpt s6 thong sd d i u vao trong phan mem Plaxis 3D dS md phdng mong be CQC nhU: cil6ng dp tai trpng ngoai tac dyng trgn mong, dd CLfng cua b i n mdng be vd each bd tri cpc ddcti b i n mdng be d l thu diJpc dd chuyen vi ciia be mdng v i t i i trpng truyen vao cpc tddng itng v6i mot trddng hpp thay doi. Kit q u i trong bai bao nay se giiip cho ngUdi ky sU thilt k l n i n mdng hilu them v l t^ 1^ phan phdi t i i trpng vao cpc v i tdng t i i trong cdng trinh dong thcti c6 thIm cO sd ty luan trong viec l^a chpn giai phap thilt k l mdng be cpc cho cac cdng trinh cao tang hiln nay.
Tit khda: Mong b^ cpc, he so phan phoi t i i trpng diing vio cpc, chuyin vi b l .
ABSTRACT
The princile of designing piled raft foundations is to examine the distribution of part of building load applying directly on the ground under the foundations. The ratio of vertical load distribution on piles and soil under raft depends on a lot of factors. The author mainly used Plaxis 3D software to consider some ftictors affecting on the ratio between the pile loads and total building load. The analysis method used in this article is changing the input data in Plaxis 3D to simulate piled raft foimdations such as: load strength on foundations, the stif&iess of raft foundations and pile arrangements to achieve raft displacement and load on piles corresponding to each case. The obtained results in this paper shows the ratio of building load distribution on pile raft foundations and the additional basis to choose the option of designing recent high-rise building piled raft foundations.
Keywords: piled raft foundations, The ratio of vertical load distribution on piles, raft displacement.
Tniofng Quang T h i n h
GV Khoa XD - DH Kiln triic TP. HCM
Tru'dng Quang Thanh
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Mdng be coc Id mdt he thdng mdng kit hdp, bao gom ede phan tQ cung tham gia ehiu luc nhu: ban mdng, cdc cpc va dSX nin bin dudi. Mdng b l cpc ed eSu tao gdm hai phan nhu sau:
Bin mdng ed nhi^m vu liln kit cdc dau CDC lai vdi nhau thanh khdi vd phdn ph6l tii trong tir ehan kit cau eho cae eoe trong be, ddng thdi truyen mdt phSn tdi trpng xudng dat nin tai vj tri tiep xue giQa ddy b^
va dSt nen
Cdc cpc Idm nhilm vu truyln tdi trpng xudng nen dat dudi ehdn cpc thdng qua siJTc khdng mui va vao nin d^t xung quanh coc thdng qua sQc khdng ben.
Tinh todn mdng be eoe da duoe nhilu tde gia trln t h i gii^ nghiln cQu. Poulos vd Davis [4], Burland [5] vd Randolph [6] dd d l xuSt cdc phuong phdp tinh todn dOn gidn ed ll^n quan den mdt sd don gidn hda trong mdi quan h$
vdi cdc sd lilu dja chat vd tdi trpng tde dung trln bdn mdng b l . Cdc phuung phdp don gidn thudng eho ra kit qud tlnh todn kim chinh xac. Mdt nhdm phQong phdp thijr hai \i phuong phdp gSn dung bdi Poulos [1] vi Clancy vd Randolph d l xu^t [2]. Nhdm phuong phdp nay xem mdng b l coc nhu m^t
"ddi trln cdc Id xo" hay "tam trln cdc Id xo".
trong dd bdn mdng b l dupe dai diln bdi m^t dai hoac dang t^m vd ede eoe nhu cdc Id xo.
Cac phUdng phdp khac bao gdm eac phuong phdp dQa trln may vi tlnh, kit hap cdc ylutfi dieu kiln biln cho phan tQ cpc va phdn tidi phan tQ hOu han cho bdn mdng b l [3],[7],[8]
Mdt sd chuong trlnh thQdng mai nhU FLAC Plaxis Foundation 3D da cung cap ede li^
chpn tdt cho mdt phan tfch sd.
Dae diem ci!ia mdng b l eoe khdc vdt mdng cpc thdng thudng dd Id phdt huy tdi da khd ndng ehiu tdi eua bdn mdng bl, trong tinh toan thilt k l cd x^t din su phdn phdi tdi trong cdng trinh xudng nen dSt dudi bdn mdng b l vd truyln vdo cpc. Hooper (1973) da nghien cijfu Qng xQ eCia mdng b l cpc eda m$t edng trinh Id khdi thap d trung tam London.
Cac do dac tai hign trudng da thUc hiln trong
5 6 E m O H X 12.2015
Bang 2.1:Thdnq sd ddu vao t r o n q m d hinh phdn tfch
T h d n g sd
Mau vat l i l u Loai v | t lieu Trong lupng r i l n g t r l n mUe
nude ngam Trpng lUpng n l n g dUdi muc
nude ngam H6 sd t h a m M d d u n d a n hdi
H I sd poisson Lue dinh Gdc ndi ma sdt
Ky h i l u Model
v^.
k E V C.rt
<P
DOnvl Ldp dat cat (sand)
M-C Drained
17
20 8.10' 2.8.1 C
0.3 0 1 34
Bdn mdng be Linear-elastic Non-porous
25
3.0.10' 0.2
Cpc Linear-elastic
Non-porous 25
3 0,10' 0.2
O a n v j
m/m'
k N / m ' m/day k N / m '
W ^ m ' d d
n h i l u ndm dUdc trinh bdy, cung vdi k i t qud chi t i l t phan tfch b^ng phQdng phap phan tQ hOu han. Cac phan tich dupe thue h i l n vdi gid d m h tdi t r p n g tde d y n g t r ^ n bdn m d n g b l Id phdn bd deu. K i t qud n g h i l n cQu thjiy r i n g mQc d d phan phdj tdi trong vdo trong coc vd d i t n i n true t i l p b i n dudl bdn mdng b l sau khi xdy d y n g xong tQong Qng Id 60 % vd 40 %.
K i t qud eua Hooper cung cho thay rdng q u i trinh cd k i t theo thW gian cCia d i t n i n lam gia tSng tdi t r p n g len cpc vd gidm dp lye t i l p xOc d3t dudi ddy b l . Nghien eOu [9] t h i y r i n g tuy thudc vdo dac d i l m dia ehSt tai noi dat m d n g b l coc md p h i n bdn mdng b l trong gidi phdp m d n g b l cpc cd t h i ganh d d t i f 30% d i n 60% toan b d tdi trpng cdng trinh.
Theo Poulos [10] khi phan tich m d n g b l cpc phdi x l t t u o n g tde giOa b l - eoe va n i n d i t . d d lun t d n g t h i eda m d n g , d d l i i n l i c h , cdc dnh hudng giCia be m d n g v d i cpc, glQa ede eoe vdi nhau.
Trong gidi phap m d n g b l eoe, t i i y theo d f c d i l m eda cdng trinh ma cd nhieu phQdng dn b d t r i cpc trong mdt bSng b i n mdng be n h i m ddm bdo t d i Uu v l d i l u k i l n kinh te va dieu ki^n ky thudt. Bd tri cpc trong mdt b i n g b l mdng phy thudc vdo muc dich eda ngQdi thiet k l , n h i m d i l u ehinh lun khdng d i u , gidm dp iQc l i n n i n d ddy b l hay gidm ndi lUc trong bdn mdng b l . Cdch bd trf cpc t r o n g b d n m d n g b l t h u d n g t h e o n g u y i n t i e trong t a m nhdm cpc triing hode g i n vdi trpng tdm tdi t r ^ g cdng t r l n h . Theo n g h i l n cQu eda Reza Zlaie - M o a y e d (2007) [11] v l Qng xii ciia mdng b l coc vdi dQdng kinh coc khdc nhau vd 6iiifc ddnh gid theo gid tri tdi trpng t h i n g diftig khdc nhau t i e d y n g t r l n bdn m d n g be.
Cdc k i t qud t h u dupe cho t h i y rSng t d n g sd d $ Idn v i d p lun l^ch cua m d n g b l epe ed the gidm d i bSng edeh sQ d y n g ede eoe vdi dQdng kinh k h i c nhau dudi b l m d n g .
2. DAT V A N Ot VA N d i DUNG P H A N TlCH
2 1 H I so phan phdi tai trpng Op.
Theo quan d i l m t f n h t o i n eda m d n g be epe t h i tdi t r p n g c d n g t r l n h vQa phan phdi len b * vifa p h a n p h d i len cpc. M d t t r o n g nhQng y l u e l u ehinh khi t f n h todn t h i l t k l gidi phap m d n g b l eoe Id phdi d a n h g i l dupe mQc d p phan p h d i tdi t r p n g c d n g t r i n h tde d y n g v i o cpc vd vdo b l m d n g . Gid sQ x l t m p t m d n g b l cpc cd t d n g tdi t r p n g t h i n g diimg cCia c d n g t r i n h ky h i l u la Rio^i, khi t r u y l n vdo d i t se t h d n g qua ap lUe t i l p xue d u d i day be ky hieu la R.^ va t h d n g qua ma sat t i l p xue giQa d i t v d i m^t b i n eoe vd giQa d i t vdi mui epe ed ky h i l u la ^^pile,i
H I sd phan phdi tdi trong cho cpc trong gidi phdp m d n g be cpc dUde m d td t h d n g qua he sd cd k;^ h i f u la Op, va dUde dinh nghia Id t l sd giQa t d n g tdi trpng t r u y l n vao cdc cpc vd t o n g tdi trpng ma ed h& t h d n g b l vh cac eoe ganh d d . N h u vay gid tri Op, theo b i l u thiJtc sau:
ndy tinh toan n h u mdng eoe t h u I n tu;^, xem n h u khdng cd su t i l p xue eda d i t ben dUdi bdn mdng be.
Mongbe MongbecQC Mongcpc 0.5 1.rf
25JWP^^-I—I 1 — I — I
DgluaS
Hinh2.1 Quanli^ap,-S ket qujnghien cuuKatzenbach (2000)
Z^P"-.'
p R r a f t + ^ R p i i e j
TQc la Qng vdi trudng hpp m d n g b l khdng cd cpc va lue nay t i n h todn n h u mdng be dat true t i l p trgn n i n dat.
H I sd QB, = 1.0 khi ^ R p [ l e . i = l^totai tlJrc
la Ong vdt trUdng h c ^ mdng eoe ddi be v i lue
«-«lKnrteHa«t
Hinh 2.2: So da mo ph6ng tUong tac mong be coc Gid sQ cd mdt m d n g b l eoe ma tai trpng tde d u n g t r l n bdn m d n g be coc phdn b d vdi CQdng d d la qt, epe dUdi be cd dUdng kinh la
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Dp vd ehiu tdi trong t i e d u n g dau epe Qp va phdn iQc d i t nen dQdi day be q,. Md phdng sU t u o n g tde mdng b l eoe theo Katzenbach et al (2000) ed b d n loai tUong t i e trong Qng xQ eda m d n g b l coc dUpc t h i h i l n nhQ t r l n hinh 2.2.
M d n g be coc la m d t gidi phap n i n mdng ed the dupe sQ d u n g de gidm t h i l u dp lun cung n h u lun lech cQa m d n g , tan d u n g dUpc khd nang chju t i i eda dat nen ben dudi bdn mdng b l va d d n g t h d i lam giam t h i l u dupc m d men udn trong b i n mdng b l . Tinh chat ndi bat nhat eua mdng be epe d d la ed xet anh hudng t u o n g ho giQa dat va k i t cau m d n g , khi d d ed m d t p h i n tdi trpng truyen xudng d i t nen t h d n g qua bdn mdng b l va phan eon lai se dQde truyen t h d n g qua cac cpc.
2.2. PhQdng phdp p h i n tfch he sd Op, Muc t i l u eda bai bao ndy la phan tfch ede y l u t d i n h hUdng den gia tr; h i sd phan phdi Qpr. Qud trinh phan tich 6 day dUa t r l n co sd sQ d u n g p h i n m I m Plaxis 3D m d phdng bdi toan mdng be eoe. Bdng each thay ddi m d t sd y l u t d dau vao ddt ra dQ k i l n se ed dnh hudng d i n sU l i m v i l e eua be coc, sil d u n g m d hinh Plaxis 3D chay bai toan d l t i m dupe cac ket qua tUdng Qng va rut ra ede nhdn xet. Phuong phap nay giOp lam rd dupe dnh hudng eda tQng t h d n g sd phdn tich den Qng xQ lun cung n h u ty 11 phan phdi tdi trpng eho epe so vdi tdng t i i trpng eda edng trinh.
2.3 Cae trUdng hdp phan tich h i sd Opr Gid sQcd mdt mdng be eoe, eac coc dUdi ban mdng b l Id lo^i cpc khoan nhdl be tdng cdt t h i p , dudng kinh cpc d= 1000 m m . Mat bSng bdn mdng be ed d^ng hinh chQ nhat kfeh thudc bxl.
Tdng sd iQOng eoe Id n, c h i l u dai epe la L, chieu ddy bdn mdng be la ky hi^u Id hb t r l n d d ed tai trpng tde dung g i i sQ la phan bd d i u vdi eUdng dd la q. Xdc djnh gia tri h i sd Op, trong ba trudng hpp bai todn dQpc dat ra de phan Heh nhQsau:
• Bdi todn 1: Thay ddi y l u t d e h i l u ddy bdn mdng (dQdc xem x l t nhQ i n h hQdng eua d i l u k i l n d d cQng bdn mdng b l )
• Bdi t o i n 2: Thay ddi gid trj cUdng dp t i i trong tde d u n g t r l n b e ( d U 0 c x e m x e t nhUdnh hQdng eua d i l u k i l n t i l trpng ngoai)
• Bai todn 3: Thay ddi eac yeu t d ve eoe (dQpc xem xet nhQ dnh hudng d i l u k i l n c h i l u dai vd cdch bd t r i coc)
B i n g 2.1: Thdng sd d i u vao trong m d hinh phdn tich
3 . K £ T Q U A P H A N TfCH CAC T R U ' O N G HOP BAt T O A N V A N H A N Xir
3.1. A n h h u d n g cCia d i l u k i l n b l day b i n m d n g b l d e n h i sd phdn phdi Up,
Bai todn 1: B i n mdng b l b l tdng cdt thep cd mdt b i n g dang hinh chQ n h i t vdi canh ngSn b = 10.0 m vd canh ddi I = 14.0 m. Sd lupng cpc dudi bdn mdng Id 12 cpc. Chieu dai cpc L = 20.0 m. C h i l u ddy b i n mdng be ky h i l u Id hh- Tdi t r p n g tae d u n g t r l n be xem nhQ
p h i n b d deu q = 200 kPa B l e u k i l n iSa chat la Idp dat cdt kha day {xem bdng 2.1).
a. C i c trQdng hpp phan tich he sd Opr.
- TrQdng hdp 1: Chieu day bdn m d n g b l hb= 1,0 m
- TrUdng hdp 2. C h i l u day bdn mdng be h b = 2 , 0 m
- TrQdng hpp 3: C h i l u day bdn mdng be h b - 3 , 0 m
Hinh 31. So do bai to^n 1 va danh so vi trf (octtong
. Ket qua danh gid h i sd Op,:
Vchuyen vj eda b i n mdng b l trong I b a t r u d n g h c p
Hinh 3.5' T] le phan phoi coc-be (bai toin 1) - Lap bang t d n g hpp k i t qud h i sd Op. v | chuyen vi be Idn n h i t eua 3 trQdng hpp
58
Thdng sd
H I sd Opr C h u y i n vi be Idn nhat (mm)
Trudng h p p i hh=1.0
0.874
20.02 TrQdng
hpp 2 hb=2.0 m 0.871
24.61 TrQdng
hpp 3 hh= 3.0
0 870 •
27.89
B i n g 3.1; Tdng hpp 3 t r u ^ g hpp phan B l i toan 1
- N h i n x l t : Trong cCing dieu k i l n iSa chit nghien cdu va cudng d d phSn bd tai trpng tac d u n g tren be nhU nhau ta nhan t h i y r i n g :
• B l day eCia bdn m d n g b l it i n h hiidng den gid trj h i sd phan phdi tdi trpng vao eoe va vao be dp,
• B l day eua bdn mdng be cang Idn thi gici tri Idn nhat eda chuyen vj be cang Idn. ^
• Trong ba bdi todn dat ra de phan tich thi t h i y r i n g h i sd Op, tang len trong khoang t£r 87.0 % d i n 87.4 % khi chieu day bdn mdng b^
g i i m dl tQ 3.0 m xudng 1.0 m ' j
• Trong trUdng hdp 1 (be day b i n moi^g, be hb= 1.0 m) k i t qud t i m dQpc cho thay rinft mdc d p chenh lech cua iQc dOtng dau c^c t r o n g mdng be epe so vdi g i i trj trung binh ede lUe nen dau eoe n h d h d n so vdi chieu day b&
hb= 2,0 m [ t r u d n g hpp 2) va hb = 3,0 m (trQdng, hpp 3). D i l u d o cd nghta Id khi e h i l u ddy bdn m d n g be n h d h d n thi lUe dOng d i u epe phin phdi d i u h o n .
3.2. A n h h u d n g ciia c u d n g d o t i i trpng n g o a i d e n he sd p h a n p h d i Op,
Bai toan 2: Bdn m d n g b l b l tdng cdt t h i p cd m a t bang dang hinh chQ nhdt vdi canh ngan b = 10.0 m v l canh d i i l,= 14.0 m. S6 iQpng cpc dudl bdn m d n g la 12 cpc. C h i l u dai epe L = 20.0 m. C h i l u day b i n m d n g be la hb = 1,5 m. Tdi trpng tde d u n g t r l n be xem nhU phdn b d d e u vdi cQdng d p ky h i l u la q. Dilu k i l n dja c h i t l i Idp d i t cdt kha d i y (xem bdng 2.1).
1 I 1 [ 11 I n
Hinh 3.6. Sod6 bai toan 2 vi d M so VI tricfc tfang b^n mdng be a. Cdc trQdng hpp phdn tieh Op,
- TrQdng hdp 1: T i i trpng phan bd deu t r l n b l q = 1 5 0 k P a
- TrUdng hpp 2. Tdi trpng p h i n bd d i u tr&n b l q = 300 kPa
- Trudng hdp 3: Tdi trpng phdn bd deu t r l n b l q = 450 kPa
b. K i t q u i d i n h g i l he sd cipi:
- B i l u d d c h u y i n vj cQa b i n m d n g be trong ba trudng hop
nraicBcvi miCNflpi nuttUB^) Hinh 310: Tl le phan phSi coc-U (bai tojn 1)
L i p bdng t d n g h p p k i t qud he sd Op, vd c h u y i n v j b l l d n n h i t eda 3 trudng hpp
Thdng so H I sd Opr Chuyin
v l l d n n h i t trong b l
(mm) TrQdng
h o p i q = 150
kPa 0.871
20.17 TrUcmg
h o p 2 q - 3 0 0 kPa 0.869
37.51 Trudng
h d p 3 q - 4 5 0 kPa 0.867
60.77
3.3. Anh hudng cua c h i l u d l l cpc va c i c h bd t r i coc den he sd phan phdi Op.
Bdi todn 3: Bdn mdng be b l t d n g cdt t h i p cd mdt b i n g dang hinh chQ nhdt vdi canh ngan b = 10.0 m v i canh dai I = 14.0 m. Sd lupng eoe dudi bdn m d t i g la 12 c p c Chieu ddy ban mdng be la hb = 1,5 m. T i i trong tac d y n g t r l n b l xem nhQ phan bd deu vdi cudng d d kj hieu 11 be q = 150 kPa. D i l u Iden dia chat l i Idp dat cdt khd ddy (xem b i n g 2.1). Thdng sd v l cpc dudl b l ed 3 loai c h i l u ddi:
Coc loai 1 ddi Li = 15.0 m. Cpc lo^i 2 d l l b
= 25.0 m . Coc loai 3 ddi U = 19.0 m
' • 4 , 0 c a - | \ 0 n . ' l ' 4 O . - l Hinh 3.11: Sad6 a^nh SO Vi trfcpcfrong bin nt6ng U (bai toan 3}
a. Cac trudng hdp phdn tieh Upr TrQdng hdp 1: PhQdng dn bd tri t i t cd cdc eoe Id loai 1 ehilu d i i cpc 15 m
TrUdng hpp 2: PhUcmg an bd tri t i t c i eac cpc Id loai 2 ehilu dai cpc 25 m
q=150kPa
11 M 11 i n
Hinh 3,8- Chuy&i vi bt miing - rnfling hop2
B i n g 3.2: Tdng hpp 3 trudng h ^ p h i n tich - Bai todn 2
- N h i n xet: Trong cung dieu ki^n dia e h i t n g h i l n cQu va c h i l u day bdn mdng be nhQ nhau (hb = 1,5 m), thay ddi ede d i l u k i l n cQdng dp tdi trong tren b i n mdng b l ta nhan t h i y rang:
• CQdng dp tdi trong phan bd d i u t r l n b l cang tdng thi chuyen vi Idn nhat trong bdn mdng b l cung tang theo, ddng thcri g i i t i i eda he sd Op. cd xu hudng gidm nhQng cung khdng ddng ke.
• MQc d d phdn phdi tdi trpng vao cpc so vdi tdi trpng toan bd eua edng trinh khdng dnh hudng nhieu vao cudng dp t i c dung eua tdi trong n g o i i l i n b i n mdng be.
• Tdi trpng p h i n bd deu t r l n b i n mdng b l CO g i l tri cang Idn thi thay r i n g gia trj li/e nen l i n cdc dau cpc trong b l ed xu hudng ddng d i u hdn so vdi trUdng hpp b i n m d n g b l chju tde dgng eua tdi trong vdi cudng d d nhd hdn.
H'inhJ.12:Sadfi(a}-tnfiinghopiva(b)-trucingh(qi2 (Bdi toan 3)
TrUdng hpp 3: Phuong i n bd t r i coc loai 1 d l l 15 m d b i l n canh n g i n va cpc loai 2 d i i 25 m d giQa nhu hinh ve
Trudng hdp 4: PhQong dn bd t r i eoe loai 2 dai 25 m d b i l n canh n g i n va eoe loai 1 dai 15 m d glQa nhQ hinh ve
1 1 1 1 11 i n
3.16: Chuyen vi be m d n g - TrQdng hpp 3
4.2. Trong dieu kien nen dat ddng nhat la Idp dat cat, d p c h u y i n vi Idn nhat trong ban mdng be cang Idn t h i he sd Op, cang nhd.
4.3 Chieu day ban mdng be khdng ddi, cu'dng do tai trpng t i e dung tren bdn mong it CO anh hudng d i n gia tri ciia he sd OD. .
d.4. Ciing m p t d i l u kien dia chat thi t i i trong tac d u n g phan bd deu tren b i n mong be cang Idn thi dp chuyen vi Idn nhat cua be CO gia t r i c a n g Idn
4.5. Dd chuyen vi Idn nhat eua be mdng t h u d n g xuat hien d vi tri tam ciia b i n mdng be va cang ra xa tam thi dp chuyen vi cang nho va tai trong tae dung tren dau coc cang Idn
W 1 1 1 1 11 1 •
Hinh 3.13'Sod6 (a) - tnldng hop 3 va (b) - trUirng hop4 (Bai toin 3)
b. K i t q u i d i n h g l l h i sd Op,:
- B i l u d d c h u y i n vj cOa b i n m d n g b l trong bon truong h p p "
m
; Thdng sd H I sd Op, C h u y i n vj be Idn
n h l t ( m m )
• ^ 1 TrQdng hdp
1 0.831
24.54
• n u r o n g hop
m 2
B M ^•^'^^
^ H 1501
l^^n^^^^^^^^^H^B '^''^
Trudng hdp 3 0.876 17 06
15.92
TrQdng hpp 4
0.886
17.70
13.87
Hinh 3,15 Chuyen vi be mdng-Iruonghop2
L i p b i n g tdng hpp k i t qud hg sd Oprl c h u y i n vl be Idn nhat eua 4 trUdng hpp Bdng 3.3: Tdng hpp 4 trQdng hpp phdn tfch - B i l todn 3
- Nhdn xet' Trong cdng d i l u ki^n dja c h i t n g h i l n cQu, c h i l u day ban mdng b6 n h u nhau (ho = 1,5 m) vd cung d i l u k i l n tdi trpng *df dung tren bdn mdng be q = 150 kPa, qua M t qud p h i n tieh ta nhan thay r i n g : ^ B
• Chieu d l l epe cang dai thi gid tri idn ^ H t ciia c h u y i n vj trong bdn mdng b l edng n h d # mdc dd phan phdi tdi trong cdng trinh \ ^ ^ ^
edng Idn. jaiS^K&
• Thay ddi e h i l u dai cpc k h i c nhau trong ddi ed i n h hudng den d d c h u y i n vi cua bdn mdnc;
vd he sd p h i n phdi tai trpng Op,.
• TrUdng hpp t l i trpng t r l n b l p h i n bd deu, n l u bd tri eoe trong pham vi giCia m d n g b l S e h i l u dai dai hon so vdi c l c epe b i l n t h i y rhm he sd phan phdi t i i trpng a„ cdng n h d va ig t n Idn nh3t eda chuyen vj be cdng Idn. ""
• Khi bd tri c l c h i n g cpc d giQa b l s i u h d n J vdi c l c hdng coc bidn (trUdng hpp 4) t h l ^ _ dp c h l n h lech gia tri chuyen vj Idn n h i t v d o n h i t eua b i n m d n g be Idn hdn so v t r u d n g hop khde da p h i n tieh.
4 . K ^ L U A N
Qua k i t q u i p h i n tich tren m d n g bem.
t r l n phan m I m Plaxis 3D vdi m d h i n h i ^ Mohr - Coulonb, vdi cae sd l i l u dSu vdo tronrj p h ^ m VI n g h i l n cQu, bdi bdo rut ra eac k i t Iudn n h u sau:
4.1 Tdi trong eua edng trlnh t ^ § ^ ^ ^ ^ ^ mdng b l eoe, m d t phan Idn t i i t r p n g 5 ^ K j ^ &
vao ede epe trong be va m d t phan k h i c ^ t r u y l n vdo bdn mdng b l khi t i l p xue vdi dat
TAI LIIU THAM KHAO
n i HG Poulos - An approximate numentfli analysis oi pile raft irtefaction - Int J Numei Anal Method Geomech, IB (1994), pp 73-92
[2] P Clancy, M.F, Randolph - An appioximate analysis procedure for piled raft foundations - Int J Numer Anal Meth Geomech,17(1993),pp 849-869.
[31 S.J, Ham, IK Lee - The analysis of flexible piie-rafl systems - Geotecimique, 28 (1) (1978), pp 65-83
[41 H G Poulos, E H. Davis - Pile foundation analysis and design-Wiley, New York (1980)
[51 Burland JB, Piles as settlement reducers. Keynote addiess 18lh Italian congress on soil mechanics. Italy Pavia, 1995,
[6| Randolph MF. Design methods for pile gmups and piled rafts SO.A report, B IGMFE, New Delhi, vol. 5,1994 p.
6 1 - 8 2
(71 H.S.W. CiiQw, J C Small - Behaviour of piled rafts willi piles of different lengths and diameters under vertical loading flSCE [3005)
[8) J.C, Small, H 6 Poulos - Nor-linear analysis of ptleit raft foundations-ASCE (2007)
[9] Phung Due Long, Piled Raft - A cost - Effectree Foundation Method for High - Rises Geotechnical Engmeenng Journal of the SEAGS & AGSSEA Vol 41 tJo 3 September 2010 ISSN 0046-5828
[10] H.G Poulos (3001), Methods of analysis of piled raft foundations, Coffey Geosciences Pty Ltd, & the University of ',dne> Australia, pp 3-9
111] Re;a aAI£_MOAYED, Meysam SAFAVIAN 12007),Pile Raft foundation behavior w i t h dilYercnl pile diameters, 4l{i International Conference on - Earthquake Geotechnical Engineering PaperNo 1114.
