Journal o i i c i e n t e u
THIET KE NEN VA MONO GIA CO COC TRE TAI HAI PHONG
Pham Thj Loan', Pham Thj H i e n " , Nguyen Van Lieu", Nguyen Quoc D u m t g "
Tom tdt
Gia c6 bdng cgc tre dd vd dang dUdc sii dung rdng rdi. Dac biet, nhUng ndi co mUc nUdc ngdm trung binh thdp ddp Ung dUdc yeu cdu sit dung cgc tre, dam bdo dUOc tuoi thg ciia cgc tre vd sU ldm viic 6n dinh cda cdng trinh.
Tuy nhien, hien nay viic sii dung cgc tre chu yiu dUa vdo kinh nghiim vd thi nghiem bdn nen kiem tra sau gia co, md chUa co dUdc he thong cd sd li thuyit hodn chinh. Vi vay, bdi bdo dUa tren cd sd dia chdt, cdng trinh vd thi nghiem bdn nen thUc nghiem tren dia bdn thdnh pho Hdi Phdng thUc hien phdn tich tinh todn nen vd mdng gia co cgc tre cho hai bdi todn mdng hdng vd mdng be di minh hoa cho phuongphdp thiit ki.
TU khod: nen ddt yeu, gia co nen, cgc tre, Hdi Phong, mongbdng, mdngbi.
1. Gidi thieu
Trong eae edng tac thiet ke nen vd mdng cde edng trinh ddn dung edng nghiep, bien phdp gia CO nln ddt ylu nhfl coc cat, dem cat, epe tre thfldng dflde lfla chpn pho biln hdn ed.
Gia ed nln bang epe tre Id gidi phdp mang tinh truyin thdng phu hdp vdi edng trinh cd tdi trpng nhd. Cpe tre cd chilu ddi tfl 3 - 5m dfldc ddng vdo trong vflng nen nham gia efldng nen dat vdi muc dich lam tang kha nang chiu tdi cua nln vd gidm dp lun cua cdng trinh.
Giai phdp gia cd nln bang cpe tre mang lai nhilu hieu qua vdi mpt sd flu viet sau:
- Tan dimg vat lieu dia phfldng, Id ngu6n nguyen vdt heu san cd.
- Dam bad khd nang chiu tdi eho edc eong trinh thap tang (dfldi 4 tang).
- Hieu qua kinh t l cao.
- Phfldng thfle thi edng ddn gidn.
Hdn nUa, cgc tre co niin han ben nin tdi 60 ~ 70 ndm vdi dieu kien ddt ludn dm. Nhiiu nhd biet thU xdy dUng tii thdi Phdp eUng dp dung ki thudt dong cgc tre de gia co nen ddt, trdi qua gdn thiki, khi ddo lin vdn thdy cgc tre dudi nen trong tinh trang rdt tdt. Tii do cho thdy, sd dung tre gia cd nen Id hodn todn hdp li vd ddng tin cdy. Ddc biet tai Hdi Phong ndi c6 do sau mUc nUdc ngdm trung binh ddp dng tot yeu cdu cua sii dung cgc tre, cdc cong trinh d&n dung thdp tdng hiin vdn cdn chgn cgc tre degia CO nin ddt yiu Id lUa chon tdi Uu nhdt.
Tuy la mot phfldng phdp gia eo nln truyen thdng va da dfldc eoi Id sfl lfla chpn kinh t l nhat, nhflng eho din nay ehfla cd tai lilu ndo dl eung cap phfldng phdp tinh toan nln va mdng gia co bang epe tre mot each hodn chinh va todn diln. Vi vay, edc tac gid da thu thdp thdng kl ngudn dfl lieu tren dia bin thdnh phd Hai Phdng. Tfl do, nghiin cflu, phan tich de dfla ra phfldng phdp tinh todn cpc tre nhfl mdt biln phap gia ed nen, giiip viec dp dung cpe tre trong cdng tdc thiet kl nen vd mdng cd cd sd li luan chat ehe hdn.
" TS., Khoa Xay ddng.
"SV., Khoa Xay dang
2. Y nghia
Gia ed nen mdng bang cpc tre la giai phap ddac flng dung rdng rai tai nhflng khu vifc cd nen dat yeu, dien hinh nhfl Hai Phdng ~ khu vfle cd ldp dat tdt kha sau (tfl 35 - 40m). Biln phap dflde sfl hieu qua cho cdc edng trinh thap tang vd nha d dan sinh. Dd la sfl lfla chpn hieu qua, phu hdp ldnh t l va ed tinh thuyet phue. Kit qua nghien cflu eung cap cd sd li luan mdt each toan dien cho quan diem tinh toan eoi epe tre la vat lieu gia co nen, cd y nghia quan trgng trong cac nghien cflu ciuig nhfl thfle hdnh thilt kl.
3. Gidi thieu dia chat va cong trinh
3.1. Gidi thieu dia chat Hdi Phong Tren cd sd thu thap phan tieh va xfl li hang tram hd sd khao sdt dia chat cioa Hai Phdng ed the ddnh gia chung ve cau true dia tang tai Hai Phdng nhfl sau:
1. Dat lap: 0,7 - 2m.
2. Bun set, set pha: trang thai deo chdy den nhao day khoang 10 - 17m.
3. Set, set pha, edt pha: trang thai deo din deo cflng ddy khoang 10 - 18m.
4. Tang dat tdt.
Cac edng trinh sfl dung giai phap nln mdng vdi epe tre md nhdm nghien eflu thu thap trong qua trinh thflc hiin nam rai rac tren dja ban cua thdnh pho. Vi vay, d l thuan tien cho bdi toan thiet kl, nhom dl tdi da phdn tieh vd Ilia chpn tru dia ehat dac trflng. Vdi cde ehi tiiu ca Ii hai ldp dat phia trln, vung nln gia ed cpc tre nhfl trong bang 1.
Bang 1: Ddc diem (Ba chdt eong trinh Seday
IB(ra) 0.5
6 Tenva trang thai
Battap
StinseJ, xmndu
Chi tieu coll
Dung trong tu Chi so did IIP) Bosetdl) Hesofongle]
LUcdlnhlC) Goc npi ma sat (e) Md dun bien dang
(E) Ap luc tinh toan
quy udc (Ro]
Chi so xuyen tieu chuan (SPll
Gia tr|TB
I.«7 M.5 1.05 U i 0.077 S.13 lUS
0.52
;
Don vi
j/t
% - -
ml la kG/c
ml K/c ml
W«l
3.2, M6 td cdng trinh
Cic cdng trinh sfl dung cpc tre gia cd nen hdu hit Id ede edng trinh ddn dung thap tang, VI vdy phfldng dn mdng dfldc lfla chpn chu ylu Id mdng bang va mdng be. Sau khi tham khdo mpt so Ifldng ldn cac hd sd thiet ke va thi cdng. Nhdm tac gia sfl dung hai cdng trinh ba tang eho hai loai mdng trln, chi tilt dfldc trinh bdy tai Bdng 2.
Bdng 2. Md td cong trinb
1 2 3 4 5 6
Sac diem So tang Dien tich mong( in ) Chieu sau chon m6ng(m) Soliidngcgctre/
m ' (COC) Chieu dai COC tre(m) Dung trong tmng bmh
Wm')
Mdng bang 3 177.02
1.5 30 3 2
Mdng be 3 13.4 5 1.5 30 2
••7-ra^*r^'«'?™"S^s^7^^
Hmh 1. Cong trinb mong bdngsddung cpc tre gia conen
Hinh 2, Cong trinh mong be sddung epe tre gia conen 4. Thiet ke nen va mong
4.1. Ap lUc cong trinh truyen xuong nen Trln cd sd ho sa ban ve edng trinh, ed the gia thilt tai trpng phdn bd diu la IT/m^ bao gom tinh va boat tdi. Tfl dd tinh todn dfldc ap lfle tieu chuan tai day mdng nhfl sau.
Fr. dien tich 1 tdng Smt dien tich mong
Ptc. Ap lUc cdng trinh truyin xuong nin dib: dung trgng trung binh cua be tong va ldp ddt tren mdng.
Hm: chiiu sdu chon mong.
Ap Iflc tieu chuan tai day mdng bang va mdng be cho ket qua nhfl trong bang 3.
Bing 3. Ap lUc tieu chudn tai day mong
n . F . l
+y -K
Trong dd:
n: s3 tdng
Cong trinh
Mdng bang Mdng be
n 3 3
F,
«
227 67S.
«
177 67
it IT/m>l
2 2
H.
w
1J5 1.5
K HM
f i 1 4.2. Sflc chiu tai cua n l n tai day mdng.
Theo cong thdc cda Terzaghi ta co:
0,5.a,.N^.b.Y + a2.Nq.q + a3.N^.i
Trong dd:
+ a: hi sd hiiu chinh theo hinh ddng mong.
Mdng ddn, mong bi:
Q,2.b 1 a^ = 1
0,2.b
= 1-
= 1 + - 1
Vdi mongbdng: a , = ttj ~ ^ 3 ~ ^ + N: hi sSphu thugegoc mgi ma sdt (tra bang) +q = d. H™
+ F^ =2:hes6an todn
Theo kien nghi eua cae tai lilu hien ed doi vdi giai phdp gia cd nen bang epe eflng nhil cpc edt, cpc trdm, eoe tre... Thfldng gia thilt sau khi gia cd sfle ehiu tai cua nen tdng len 2 - 5 lan so vdi trfldc khi gia cd. Trong pham vi nghiin eflu cua d l tai ehpn sfle chiu tai cua nln tang len 2 lan so vdi ehfla gia cd.
Bdng 4. Hi so trong e6ng tbUc Terzagbi
Cong trinh Mdnqbanq
Mdnqbe ai
1 0.925
a i 1 1
d) 1 1.075
Hi 1 1
Nq 1.62 1.62
Nc 6.6 6.6
c n/m')
071 0.71 Bang 5. SUe cbiu tdi cOa nen tbeo Terzagbi Cong
trinh Mdng bang Mdng bi
a ff/m')
1.67 1.67
b (ml 1.6
S
'*
(T/m)
9.67 12.96
Fs
2.5 2.5 n
2 2
IPI ( I M 7.736 10368
pn
m
6.5 6
Y J . . + T I . ( F - F „ )
<'b,=r'-h.,+Tg.-l',.
''g,=k„.(P.-y.hJ
Trong do, ko tra bdng thuoc do sdu vd hinh ng mdng.
Bdng 6. Kiem tra Idp ddt dUcfi mdi cpc tre
Dfla vdo ket qua bang 6 thdy, dbi< 10.
dgido dd edn tien hanh kiem tra cfldng dd dat nln tai mat ldp dat mui cpe tre.
4.4. Kiem tra svtc chiu tdi cda nen tai miii COC tre
Vdi n la hi so chi do tdng cUdng do cua nen ddt sau gia co.
Theo kit qud tinh todn trong Bang 6, cho thay thay Ptt< [P]. Nhfl vay nln ddt dfldi ddy mdng dfl sflc chiu tdi cho cdng trinh.
4.3. Dieu kien st^c chju tdi cua nen tai mui Cpc tre
Tai do sdu z:
- Vngsudt do trgng lUdng bdn than:
Hinb 3. Mat cdt mdng sCf dung cgc tre gia conen
Xae dinh kieh thfldc khdi mdng quy fldc:
(dung trgng sau
gia cS)
Ta eo: di= 0.725 T/m^ (dung trgng tre) - Ifng sudt gay ldn do tdi trgng ngodi gdy ra tai mdi coc tre:
- Xdc dinh dng sudt dUdi miii cgc tre:
Lay gdc md fl=10'' nghia la tang khoang 2 ldn so vdi gdc ndi ma sat cua nen trflde khi gja co.
0ng suat dfldi miii epe tre theo tflng loai mdng dfldc the hiin trong Bang 7.
Bing 7. tXng sudt dUcfi mdi cpe tre
Cdng trinh
Mdng bang Mdng be
a' (7/
1.67
1.67 h.
(m 1 1.3 5 1.5
a«
IT/m
')
0.80 75 0.80 75
lc(
(m
!)
1 1
3 d>, 17/
468 4.93
P»
a/
mj 6.5 4 e
K.
0.6 8 0.6 9
a*
m'l 2.03
1.84 Cong trinh
Mdng bang Mdng be
a' (W
1
1.67 1.67
hm Iml U 5 l i
d- (r/m-
1
1.67 1.67
L Im 1 3 3
o".
mm' 1 7.26 7i2
k.
0J6 7 0.6
P"
)
6.54 6
if ir/mi
1 US 1.77
TAP CHl KHOA HOC Vol 04. No. 16 - S/3016 I 5 0
Xdc dinh sfle chiu tai ddt nen tai mui cpe tre theo Terzaghi:
P' 0,5.a',.ii',.l>»„T'+'^'!-"Vl'"'"°''5 •"'=•*''
[ p i - f = .^
Bing 8. Hi so trong cong thdc sdc cbiu tai nen theo Terzagbi
:^+CT^',<[P']
Nhfl v|y, nln dat dfldi mui epe he dam bao dilu kiln sflc chiu tdi.
4.4 Dieu kien bien dang cda nen
Cdng trinh
Mdng bang Mdng be
a'l 1 0.91
a'l 1
1 a ' ]
1 1.09
K'l 1 1
N'<
1.62 1.62
N'.
6.6 6.6
<:
(i/m'l 0.71 0.71 Bing 9. Sut chiu tai cila nen tgi miii cpc tre
Cong trinh Mongbdng Mdng be
a' (i/m-j 1.67 1.67
b„., Im) 2.66 6.06
P'gh (i/m'l 18.7 21.9
F, 2 2
[P'l (i/m'l 9.34 10.9
d^i+d, (i/m'l
8.61 9.29
Kit qud bdng 9 cho thay tdng flng suat ban thdn vd flng sudt gdy lun nhd hdn sflc chiu tai efla nln tai miii cpe tre.
Trong do:
P = 0,8
Ung sudt gdy ldn tai do sdu z (5*, =k„.o^',
E-, mo dun biin dang cua ldp ddt i, md dun bien dang E sau khi gia edse tang gdp 2Un md dun cua ldp ddt tU nhien.
Chia nhd ede ldp dat dfldi day mdng troi^
pham vi d^ ddy nen liin thanh eae ldp phdn to c6 chieu day hi < b/4. Chi tilt thi hiin qua bang sau:
Ldp dat 1
2
3 Be day
Oi
6
4.7 hi l i Oi Oi Oi Oi Oi Oi Oi Oi Oi Oi Oi
2i l i 2 2i 3 3.5 4 4 i 5 5.5 6 6.5 7
d"
2 i 3.3 4.1 i 5.9 6.7 7.6 8.4 9.3 10 11 12
Bang 10. Bg lun mong bi z/b
0.4 0.5 0.6 07 0.8 0.9 1 1.1 1.2 1.3 1.4
l/b
2.7 27 2.7 27 27 27 27 27 2.7 2.7 2.7
K.
0.88 0.81 0.74 0.6S 0.62 0.56 0.51 0.47 0.43 0 39 0.36
i'.
2 95 2.95 2.95 2.95 295 2.95 2.95 2.95 2.95 2.95 2.72 2.72
d",
2.58 2.38 2.19 2 1.82 1.66 1.51 1.38 126 1.07 0.97
Ojift
2.58 2.48 2.29 2.1 1.91 1.74 1.59 1.45 1.32 1.17 1.02
E
435.6 435.6 435.6 435.6 435.6 435.6 217.8 217.8 217.8 650 650
5i
0002 0.002 0.002 0.002 0.0O2 0.002 0.003 0.0026 0.0024 700E-04 6.0OE-O4
S
Bang 11. Dp lun mdng bang
Ldpdlt 1 2
Be day 1 e
hi 1.4 0.4 0.4
Zl 1.4 1.8 2.2
6\
2.3 29 3.6
l/b
1.1 1.3
K.
Oi 0.4
d",i 3.69 3.69 3.69
d',
1.91 1.61
6".
1.91 1.76
E
436 436
SI
0.001 0.001
s
0.0083
Ldp dat Be day hi 0.4 04 0.4 0.4 0.4 0.4 0.4
Zl 26
3 3.4 3.8 4.2 4.6 5
d".
43 4.9 5.6 6.3 7 77 8.3
z/b 1.6 1.8 2.1 2.3 26 2.8 3.1
K.
0.4 0.4 0.3 0.3 0.2 02 0.2
d'a 3.69 3.69 3.69 3.69 3.69 3.69 3.69
d*.
1.39 1.34 1.1 1 0.92 0.82 0.74
d".
l i 1.37 1.22 1.05 0.96 0.87 0.78
E 436 436 436 436 218 218 218
Si 0.001 0.001 9E-04 8E-04 7E-04 0.001 0.001
s
Theo kit qua ciia bdng 10 va 11 do liin cua eae mdng deu nhd hdn 8cm, vay thoa man dieu kiln biln dang eua nln theo quy dinh eua tiiu ehuan.
Thiit bi thi nghiem bao gom:
5. Kiem chuTng bang thi nghiem ban nen hien trifdng
5.1. Gidi thieu thi nghiem
Hinb 4. Thi nghiim bin nen bien trUdng Thi nghiim ban nen hien trfldng cho phep quan sat sfl Idm viec tfldng tfl efla mdng edng trinh nhflng cd kich thfldc nhd hdn. Qua do cd the quan sat dfldc trang thdi ldm vile ciia ban nen xay dflng ed sd suy diln chd
mdng ndng cd kieh thfldc thfle. Dd ehinh la cd vd khdng be qua lam thi nghiim keo ddi.
He thdng neo xoan bang thep.
He thdng dam gdnh bang thep.
Ban nen vudng 50cm x 50cm 2.500cm^
Tang tdi trpng bang kich thuy lflc cd gan ddng hd do dp lflc.
Do bien dang eua tam nln bang ddng hd ed dp ehinh xde 0,01mm.
Ket eau cua thilt bi eho phep tdng tai trpng theo tflng cap dp lfle tfl 0,1 kG/cm^ den 1 kG/em^. Vile ehpn cap tdi trpng theo hfldng dan eua quy trinh nen sao cho phii hdp, khdng ldn qua lam giam tinh chinh xae cua thi nghiim vd khdng be qua lam thi nghiim keo ddi.
Vile ehpn cap tai trpng theo hfldng dan eua quy trinh nen sao eho phu hdp, khdng ldn qua lam gidm tinh chinh xae eua thi nghiim sd xuat hiin loai thi nghiem ban nen tdi trpng
tinh (Plate Bearing Tets) sfl dung eho Idem tra va thilt ke mdng ndng ciing nhfl eho thilt ke tan phu mat dfldng giao thdng.
Phfldng phap thi nghiim bdn nln tdi trpng tinh thdng thfldng dflde tiln hanh theo tieu chudn TCVN "9354; 2012 - Dat Xay dflng.
Phfldng phap xae dinh module bien dang tai hien trfldng bang tam nen phang"
Viic tien hdnh thi nghiem dUde thdc hiin theo quy trinh sau:
Sau khi xudng neo xoan ijt = 250nim vdo dat nln dl tiep nhan phan lfle khi gia tdi gd lap he thong dam gdnh: Can bang he thdng ddm bang cdc vit me, chuan hi vi tri hd nln: Tao mat bang vi tri nen, khi can thilt ed thi dim cat mdng, dat ban nen len vi tri dd ehuan bi sao eho ban nen tiep xue vdi nen. Dat kieh
TAP CH( KHOA HOC V o l . 04, No. 16 5/2016 I 3 1
thuy Iflc Iln bdn nen va ga he thdng ddng hd S.2. Kiem chCtng bang ket qud bdn nen do dp liin cua tam nen. hien trUdng
Cdng tae thi nghiem va theo ddi dp Ifln tai 5.2. / .Ket qua thi nghiem ban nen hien trddng hien trfldng tuan thu theo edc quy trmh, quy Thi nghiim ban nln hien trfldng Id thi pham eua Nha nfldc dd ban hanh. Dien hinh nghiem can thiet va quan trpng ddi vdi nen la TCVN 9354:2012 "Dat xay dflng gia cd bang epe tre, dde bilt Id khi ehfla co cO Phfldng phap xdc dinh module bien dang tai g^ ]{thuylt tinh toan hoan chinh. Do vay, bai hiin tnidng bang tam nen phang". bdo sfl dung ede kit qua thi nghiim ban nen dfldc eung eSp tfl cac cd quan qudn li xay dflng va eae ddn vi tfl van thiet kl. Kit qua mdt so thi nghiim the hien trong bang 12.
Bdng 12. Mptsokit qui tbi nghiim ban nen
Hdnen
HNI HN2 HN3 HM BUS H»6
Cap ap lire P(itG/cm')
f.
0,4 0,4 0,4 0,4 0,4 0.4
i f 0,6 0,6 0,6 0,6 0,6 0,6
He so an toan If
2 i
DdlunS(cm)
5.
0 0.1 0.1 0.1 0.1 0.1
5r 043 0.55 0.58 0.62 0.45 0.52
as
0.442 0.478 0.491 0.507 0.418 0.44
T.Tcuchan
Ptllie/ai'l
1,63 1,55 1,54 1,43 1,63 1,55
MddunBD
[(l£/m'l 48,85 45,74 43,92 4 2 i 4 48,85 45,74
Sllcchjutjl ciia nen
Pi/Ktji') 0,65 0,62 0,62 0,57 0,65 0,62
Theo kit qua trong bang 12 cho thay sflc ehiu tai cua nln ddt sau khi gia ed tren dia ban thdnh phd Hdi Phdng dat gid tri trung binh la 0,61 T/m^ vd md dun bien dang tnmg binh la 45,94 I^cm^. Trong thiet ke sd lieu, bai toan sfl dung gid tri trung binh, vdi [P]pac5 = 0,61 kG/cm^
eiia thi nghiim ban nen thi edc ket qud tinh todn thoa man. Vdi dia ehat nhfl Hai Phdng sfl dung phfldng phap gia cd nen ddt bang cpc tre vdi he so tang sflc chiu tdi eua nln sau gia cd bang 2 Id phu hdp vdi ket qud thflc nghiim.
5.22. Kiem chdng dieu kien stit chiu tai cOa ne/i Theo kit qua t^i bdng 5 cho thay ap liic tiiu ehuan tai ddy mdng (P"^) tai day mong bang Id 6,5 T/m^, mdng be la 6 T/ml So sanh vdi kit qud kit qud sfle ehiu tdi tnmg binh cia thi nghiem ban nln [P]ga c6 = 6,1 T/m^ cho thay nln dam bao sflc chiu tai.
5.2.3. Kiem chting dieu kien bien dang cOa nin Theo kit qua cua thi nghiim ban nen hien trfldng ta tinh dflde do Ifln eua mdng.
Bdng 13. Op lun mong be tinh tbeo tbi nghiim ban nen Ldp d a t
1
2 Be day
Oi
6 hi l i Oi Oi 0.5
Zl l i 2 2i 3
d"
2i 3.3 4.1 5
lib
0.4 Oi 0.6
l/b
2.7 2.7 2.7
K.
0.88 0.81 0.74
d«.
2.95 2.95 2.95 2.95
d",
2i8 2.38 2.19
OgM
2.58 2.48 2.29
E
459.4 459.4 459.4
SI
0.002 0.002 0.002
s
0.017
3 2 I T R I / O N G O A I HOC HAlPHdNG
Ldp dat
3 Bediy
4.7 hi Oi 03 OJ OJ OJ 0.5 Oi Oi
Zl 3 i 4 4J 5 Si 6 6.5 7
d"
5.9 67 7.6 8.4 9J 10 11 12
z/b 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4
l/b 2.7 2.7 2.7 27 27 2.7 27 2.7
K.
0.68 0.62 0.56 0.51 0.47 0.43 0.39 0.36
d«.
2.95 2.95 2.9S 2.9i 2.95 2.95 2.72 2.72
d».
2 1.82 1.66 l i l 1J8 1.26 1.07 0.97
di»
2.1 1.91 1.74 1.59 1.4S 1.32 1.17 1.02
E 459.4 459.4 459.4 459.4 459.4 459.4 459.4 459.4
SI 0.002 0.002 0.002 0.001 0001 0.001 0.001 9.00E-04
s
Bing 14. Dp lun mong bdng tbeo tbi nghiim bdn nen Ldpdat
1
2 Be day
1
6 hi 1.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4
Zl 1.4 18 2.2 2.6 3 3.4 3.8 4.2 4.6 5
d".
23 19 3.6 43 4.9 5.6 6J 7 77 8J
z/b
1.1 13 1.6 1.8 2.1 23 16 2.8 3.1
K.
Oi 04 0.4 0.4 03 03 01 01 01
d".
3.69 3.69 3.69 3.69 3.69 3.69 3.69 3.69 3.69 3.69
d'.
1.91 1.61 1.39 134 1.1 1 0.92 0.82 0.74
6*»
1.91 1.76 l i 137 112 1.05 0.96 0.87 0.78
E
459.4 459.4 459.4 459.4 459.4 459.4 459.4 459.4 459.4
SI
0.00133043 O.0O122595 0.00104484 0.00095429 0 0008498 0.00073139 0.00066S7 0.00060601 0.00054332
S
0.00795
Khi dng sudt ban than Idn hdn 10 lan flng suat gay liin do tai trpng ngoai gay ra, ta dflng tinh lun. Tfl ket qua Bang 13, 14 eho thdy dp liin mdng bang tinh theo thi nghiim bdn nen la 0,017m, mdng be Id 0,00795m, nho hdn 0,08m vd nhd hdn ca dp lun theo tinh toan (mdng bang 0,02m vd mdng be 0,0083m).
Vay, tinh toan li thuyet gia cd nln bang epe tre thoa man dilu kien biln dang cua nln.
6. Ket luan
Tren cd sd cac kit qua cua nghien cflu dfldc gidi thilu trong bdi bao, eae kit luan dflde nit ra nhfl sau:
- Vile sfl dung epe tre eho giai phdp nln mdng cae cdng trinh xay dflng dfldi 4 tang trong dilu kiln dia chdt Hai Phdng Id hieu qua.
- Phfldng phap thiet ke nen va mdng gia cd cpe tre dflde dl xudt kiem chflng bang thi nghiim ban nln cho dp tin eay eao.
-Sau gia ed bang cpe tre, khd nang lam vile eua nln tang khoang 2-3 lan.
-Ket qua nghien eflu eung cap cd sd li luan day du cho bdi todn xfl li nen dat ylu bang epe tre, ed y nghia quan trpng trong nghiin cflu vd thflc hanh thiet ke.
T A I L I £ U THAM KHAO [1] Ll Dfle Thang, Bui Anh Dinh, Phan
Trfldng Kiet, Nen vd Mdng, NXB giao due Ha Ndi, 1998.
[2] Nguyen Vdn Qudng, Nguyen Hflu Khdng, Udng Dinh Chat, Nen vd Mong Cdc cdng
TAP CH( KHOA HQC Vol. 04, No. 16 - S/2016 | 3 3
trinh ddn dung vd cdng nghiip, NXB Xay Dflng Ha Ndi, 1996
[3] Le Dfle Thang. Tinh todn mong cgc, NXB Giao thdng van tdi HdNdi, 1998.
[4] Vu CongN^, Thiitkivd tinh todn mdng nong. Trfldng dai hpe Xdy Dflng.
[5] Nguyen Van Quang, Nguyen Hflu Khdng.
Hudng ddn do dn nen vd mdng, NXB xdy dflng HdNdi, 1996 [6] NguyaiVanQudn^NCTTmdngn/Ki
coo (^NXBKhoahpcvaKAudtHaNpi, 2008 [7] Nguyen Uyea Xii" ft'MEM ddtyiu
/TOtt^xdy rfyng NXB Xay Dflng HdNdi, 2005 [8] I'cmWmY'^Cdmnangdimg
dm IdsU^ fd^udt NXB 3QyDflr^HaNdi, 2004 [9] TCVN 9354-2012: Ddt xdy dUng- phUdng phdp xdc dinh module bien dang tai hien trUdng bdng tdm nen ph^ng.
SOIL AND FOUNDATION DESIGN WITH SOIL IMPROVEMENT BY
BAMBOOS EST HAIPHONG Abstract: The method of soil improvement by using bamboos for construction foundations has been widely used. This solution is especially suitable in case of the field with low level groundwater because the bamboos are covered by water and the struture works well thanks to the increase of bearing capacity of shallow foundations. However, there has no comprehensive theory of soil and foundation design with soil improvement by bamboos, applying bamboos relies on the experience and tests in-situ after improving the foundation.
Therefore, this paper analyses the soil infrastructure, the construction and compressing testing in Haiphong city so as to calculate the ground and the foundations which need strengthening with bamboos for both strip and spead ones.
Key words: difficult soil, soil improvement, bamboos, Haiphong, strip foundation, spread foundation.
3 4 I TRfldNG DAI HOC HAlPHdNG