Phan tfch mot so yeu to anh hUcrng den ci^dng do ap life ngang cua dat co lien quan den do on djnh cua cdng trinh tudng chan cuTng dang cdng - xdn
Analysis of some factors affecting the intensity laterial earth pressure related to stability of rigid cantilever retaining wall
Ngay nhan bai: 13/02/2017 Ngay SLi:a bai: 8/3/2017 Ngay chap nhan dang: 5/4/2017
T ( 5 M
TAT:
Khi tinh toan thiet ke eong trinh til6ng ch4n ciJng deu phai kiem tra do on dinh v^ chuyen dich cua tUdng cung nhii kha nang chiu tai cua n^n tai day mong ciia tiling ch5n. Do 6n dinh cila c6ng trinh tu6ng chan phu thupc nhieu v^o cil6ng do ap ldc ngang tac dung len no. Bai hao nay se phan tich mot so yeu to co anh hudng den gia tri ap lUc ngang cua d3t tac dung len tiidng va co lien quan den do on dinh cua eong trinh tu6ng chan ciing dang cdng xon chan gifl kh6i dat r6i, kh6 v i dong nhat. K^t qua phan tich nay dUa tren ly thuyet ap luc dat ciia Coulomb.
Tif khda: Dp on dinh cua tifcfng chan ciing, ly thuyet ap Itfc dat Coulomb
ABSTRACT:
When design a rigid retaining wall, we have to check the stability of translation^ wall and load bearing capacity of soil at the bottom of foundation. The stability of a retaining wall depends on the intensity ofthe lateral earth pressure. The purpose of this article will analyze some factors that affect the value ofthe lateral earth pressure exerted on the wall and it relates to the stability of the rigid cantilever retaining wall that supporting a dry, homogeneous soil. This analysis based on earth pressure theory of Coulomb.
Keywords: Stability of rigid retaining walls, earth pressure theory of Coulomb
TS. T n i o n g Quang Thanh GV khoa XD - Dai hoc Kien triic TP.HCM KS. Nguyin iWanh Tri
Hoc vien Cao hoc XD22-Dai hoc Kien triic TP.HCM
Tru'dng Quang Thanh, Nguyin Manh Tri
1. TONG QUAN
Cdng trinh ti/dng chan dat duac thiet ke dung din phai thoa man hai y^u cau doc lap nhau [1]. Thd nhat, phai dam bdo cdng trinh an toan chdng pha hoai lat va iiin qua miJc, ap luc day mong phSi khong vifot ap iUe cho phep ciia 3it; hdn nfla tdng the c6ng trinh phSi co hi sd an toSn 3ii chdng tryot dfliSi day mong ThiJ hai, toan bd c6ng trinh vi tflng bo phan cua no phii du do ben tren co sd kiem tra do ben ket cau tai cac mat c3t tdi han khac nhau cua tUdng.
Thiet ke eong trinh tudng ch3n kieu eong xon thudng phiJc tap hon kilu trong lu'c nhflng noi chung cung bao gom q u i trinh tinh t h i i vi hieu chinh cho den kht thda man cac dieu kien ve do ben, do on dmh va hieu qu3 kmh te. Tai trong chinh va ch6 yeu tac dong len eong trinh tfldng chan do la tai trong theo phflong ngang va do chinh Id ap Iflc dat.
1.1 Ly thuyet Coulomb ve ap lUc ngang
Poneelet (1840) da sfl dung phflOng phap cSn bang gidi han cua Coulomb [ 2 ] , thu dflOc bieu thflc h f sd ap Iflc dat chu dong va bi dong Kit va Kpc ddi vdi trfldng hgp tUdng ma sat (6), mat tudng nghieng mot goc n so vdi phflong thang dflng, va dat d i p rdi, mat dat dap nghieng mot goc |B so vdi phflOng ngang (hinh 1) Gia tr; he soK^vaKpc dfloc tinh theo eong thiJfc (1) va (2).
cos'(l)^'-r|]
K , , = -
.',cos(,.5 i.H.*'-^'-""^'-pr
[ |cos(n+5)eos(Ti-6j cos'(i|>'+ri)
(1)
cos^riC0S(n-5) 1 Jsm(^'+8)sin(<^'+|3|
|cos(ri-6)cos(ri-6j
Cac he so ap luc ngang cua 3it dfloc ap dung cho cae trfldng hop flng suat hieu qud va khong phai iJTng suat tong.
1.2 Ly thuyet Rankine ve ap \\lc ngang
Rankine [2] da xay dflng each tinh ap Iflc ngang cfla dat cho trfldng hop Iflng tudng nhSn, thiing dflng va chan gifl m^t khdi dat khd, ddng nhat vdi be mat 3it dap nam ngang. Chu (1991) da m d r o r g ly thuyet Rankine va bat nguon til bieu thOre K* va Kp cho mot khoi dat vdi be mat dat dSp va vdi lung tfldng nghieng doc.Vdi cac ky hieu tren hinh 2, cdc he sd dp Iflc ngang cfla dat theo phan tich cua Rankine la:
0 4 . 2 0 1 7 B a ! l i l l E [ I S I X 1 ^ 7
//,.
t
3
1
P^'^a. B^ TiSt ma sat / W - ^ , /
^^^/jJ-^-A / / Mai phIng t
^'^^'•S'^"^'^ / ff-J = ! ^ <^.^-.°\/ Y "
Trong dd T Id sflc khang trflot tai day tfldng va ?„. la cac Iflc ngang day vao tUdng. Sflc khdng trfldt tinh theo cdng thflc T=R,tanij)„'e|
phan tich flng suat cd hieu va tinh theo cdng thflc T = s„B khi phan tich flng suat tdng. Thanh phSn Iflc t h i n g dutig ky hi&u Rj, va ^t, 1^ gdc ma sat tiep xfle gifla day tfldng va dat nen.
H'inh 1: Ap lUc flat chii Sbnq iheo Coulomb v6i lUtingchan ciJng doc, tutmg m dat dip nghieng
li.
l \
+|i /
" / 1;. /
/i.-' / - Phap tuyen mat
\^'f pfianglru'ot
/ "
Hmh 2 Tuang ciing, nhin co lung li/ong va
h :
at dat dap nghieng tiieo phLiang phap cos(p-cos cos(p
ri).7l + S ' " ' * ' ' ri(cosP + Vsin r i ) ^ l + s i n ' * ' 4
2sini)i'cos(o^
*'
2s -sin n * ' P) oscflj
(4)
P. —K,„y'H/
(5)
Pp=-Kp.y'H„ (6)
Trong trudng hop Iflng tfldng t h i n g dung, n = 0 phflong trinh (3) va (4) thu gon:
K,p = [ e o s p - V c o s ' p - c o s ' f I + y c o s ' p - c o s ' i j ) '
Cdc luc ngang chfl ddng va bi ddng theo hudng song song vdi mdt ddt dap tfle la cd nghieng mdt gdc p so vdi phuong nam ngang. Do do
P^. =P,cosp va Pp, =PpSinp
2. KIEM TRA DO 6 N DINH C Q A C 6 N G T R I N H T I / O N G C H A N CC^NG 2.1 D d on dinh ttuat phang
Tudng chSn ndi chung phai cd du sflc khang de chong lai sUtrUot.
Sflc khang trflert tai day tUOng phai Idn hon cac Iflc ngang day vdo tfldng He sd an toan chdng trfldt, (FS)Tla-
{FS)T =
Hinh 3. Cac Itfc tac dung len tuong chan cUng trong luc va tUimg dang eong - xan Phan tich tdi trong tac dung len tfldng trong lUc va tfldng cdng - xon ed be rong day tfldng la 6 nhfl tren hinh 3. Sfl dung phfldng phap cari bSng tinh hoe, chung ta cd dUdc:
[(W„ + W , + P „ ) c o s e b - P „ s i n 0 b ] t a n e t
~ P,.cose^+(W„ + W,+P„)sineB
Trong do W „ Id trong Iflong cua tudng, Wi Id trong Iflong cua dat dap tdc dung len tfldng, Pai vd Pj, la thanh phan lye chfl dong dflng va ngang, va ^^ la do nghieng cfla chan tfldng vdi phUdng nSm ngang.
(FS),. ' - ° ' ° " ' - P„eose^ + (W^+W, + P^)sine^
Trong do, Sv, la sflc chdng cat cua dat tai day tudng. Neu 0^ = 0 thi:
' * cos'n(cosp-Vsin^ij)'-sin'p)
Cac quy Ude ky hieu cho n va P dfloc the hien trong hinh 2; dau (+) khi gdc cd chieu xoay ngfloc chieu kim dong ho. Cac ap luc ngang chu ddng va hi dong d trang thdi ung suat gidl han Id'
Phdn ban ddy tUdng chan cdng xdn dfloc chon khdng sau vao dat nen va Iflc ngang bi ddng bd qua. Neu kha ndng khang trfldt khdng dd can tang them ehieu rong B cua day tfldng.
2.2 6 n djnh xoay
Tfldng chan cflng phdi cd du sdc khang de chong xoay. 6n dinh xoay cfla tfldng thda man neu tong hgp luc doc dfla ve ddy tUdng co diem ddt trong pham vi td mot phan ba den hai phan ba bi rdng day tudng. Oilm flat luc doc tai chan tUdng trong trfldng hop 8^ = 0 nhfl sau:
(7)
W„x +W,x, - P ^ z , W ^ + W , + P „
Trong dd T, la vi tri cfla lUe ngang ehd ddng cfla dit tinh t f l ciidti tudng.Tudng du an toan chong xoay neu — < x £ - ^ , hay d d lech tam, .
3 cfla iflc t h i n g diing tai ddy tudng e =
2.3 Kiem tra kh<i nang chju t^i
Ddy tfldng chan dat tr^n dat nen, do vay can phai kiem tra sdc chiu tai cua nen dat tai day tudng phdi cd dfl do an toan ve kha ndng chiu tai cua dat. Ap Iflc tdi da tac dong vao dat tai chan tfldng khdng dUoc vfldt qua sflc chju t^icho phep cfla dat, tfle id.
T r o n g d 6 : ( o J „ „ - a p l f l c t h 3 n g d u n g l d n n h a t t a i d d y t f l d n g , q^ -sflc chiu tdi cho phep cua dat.
2.4 6n d j n h trUOt sau
TUdng c h i n cd the bi pha hdng neu khdng dam bao dieu kiSn dn
^ n h trfldt sdu. Khoi dat ben dUdi day mdng tudng bi tfUOt theo cdc mat trUot. He sd dn dinh cung trfldt phdi cd gia tri dii Idn theo tieu chuan qui dinh ve thi^t ke tfldng chan.
2.5 6 n d j n h t h a m va xdi ngam
Mot tudng c h i n cuTig phdi d i m bSo on dmh tham vd xdi n g i m
(FS), . T r o n g d d (FS), ldh§sdai n cho sfl tham. Oe tranh sfl pha
Hinh 4: So do tucmg chin Irong bai toan phan tich
TUdng chdn: Bi rong day tfldng B = Bl + 82; Ba - Be rdng dinh tfldng;Vr Dung trong vat lieu lam tfldng; n - Gdc nghi&ng Iflng tfldng; U - Chi^u cao bSn mdng tudng, U - Chieu cao thdn tfldng; Ua - Chi^u cao d i t d i p phia tr&n dinh tfldng.
Bdtddp:^- Gdc nghieng mat dat d i p ; 6 - Gdc ma sat ngodi; [p'«- Gdc ma sdt trong dat dap; V>JI - Dung trong dat dap; q r Hoat tdi tren mat dat d i p .
Bdt nim v»f - Dung trong dat nen;<p'p - Gdc ma sat trong dat nen; ^^
- Gdc ma sat tiep xuc gius day tfldng vi dSt nen.
Ki^m tra do on dinh cua eong trinh tfldng chan dat theo cdc budc dfldc tdm t i t nhflsau'
BUdc 1 Xde dinh gia tri dp iflc dat chu ddng va vi tri d i l m ddt
- He sd dp Iflc dat chfl ddng ICc theo cdng thflc (1) - Xde dinh chieu cao Ho= Lm+Lt+L*i - Lflc ngang chfl ddng t f l khdi dat P,^ = —K^y,„Ho
Tach [fle P.itthanh hai thanh p h i n ngang vddiJngky hieu la Ps,vaPsi -P.. = F „ + F . ^K^^O^HQCOSS
-P..=P« + P,=K>cqsHi,5inS
Bu'dc 2: Xac dmh tdng gia tfl Iflc t h i n g dflng tai day tudng tudng vd VI tri diem dat (tinh eho mot don vi chi^u dai tfldng c h i n )
- Lflc t h i n g dflng tai ddy tfldng (R,) la tong cdng cua trong lUdng bdn thdn tfldng, dat d i p , phu tai tren mat dat d i p va thanh phan Pa,
- Diem dat cfla thanh phan lflc theo phuong ngang Ps. each ddy tfldng.
F.'i + F.i
: _ " 3 ' 2 hoai hen quan din hiin tfldng tham, trong dat dap can ph^i thiet ki v l n
de thodt nfldc de tieu tan nhanh chdng ap luc nfldc 16 rong d f l thilia M 6 t sd n h a n xet:Trong tinh toein thiet ke tUdng c h i n cflng, c h i n giO khdi dat d i p c i n phdi kiem tra do on dinh cfla cdng trinh tUdng c h i n . Ndm tieu chi kiem tra do dn dinh cho cdng trinh tfldng c h i n ndi tr#n can phai dUOc thda man de dam bao cdng trinh tfldng chan lam viee an todn.
3. P H A N TfCH MOT 5 0 Y^U T 6 A N H HlTdNG D^N C I / O N G D d AP Ll/C NGANG C O A DAT CCt ANH WSiSHG D^N DO ON DjNH CCiA C 6 N G TRlNH T I / O N G C H A N CUTNG DANG C O N G X O N TRONG M O T T R I / O N G H O P C U T H i
Gia sd mdt tfldng c h i n cflng dang cdng xdn vdi ky h i f u cdc thdng so tren hinh 4, gdm ed:
- Diem dat cua hop Iflc t h i n g dflng cdch mep trudc chan tUdng:
x = ^ ^ R,
BUdc 3: Xac dmh do lech tam ciia hop lUc thang dung tai ddy tfldng k>Jhi§ulde: e = — x
lU JI
Budc 4: Xac dinh dd on dinh cfla tfldng
- So sdnh do l§eh tdm e va B/6 de ket luan dd dn dmh xoay cua tfldng.
d n ^ n h trUpt p h I n g cua tudng: (FS), = — . Trong dd: T = R^ taniji^
- Kha nang chju tai cfla dat nen tai ddy mdng tudng:
+ Ap Iflc Idn nhat tai ddy mdng tfldng: ( o , ) „ , = ^ ( l - i ) Bxl B B ' - B - 2 e , H - P , . , V „ - R ,
a>-tan-' —
= {2 + f ; ) / ( l + f - ) = 2 N,=01054exp(9.6(t)p)
-0.5yB'N,i, tFS)„ ^ qu 3.1 D|it cdc bai toan phan tich
Gid sfl cd cdng trinh tfldng chan dang c6ng - xdn thi hi§n tr^n hinh 4 v d i c a c g i d t r i n h u s a u '
Tudng c h i n : Be rdng Say tfldng B: B1= 1 8 m; B2= 3 m; Ba= 0.4 m;
l ^ = 0.9 m; L,= 6 1 m Dat d a p : p = 8"; 6 = 15°, t p ' „ - 25", Y«t= 18.5 kN/m';
q.= 2T/m^Oatnen:v»l=19kN/m';<p'c=3S"; <p^ -28" Myc n Ude ngam d do sau 8 m dfldi day mdng tfldng c h i n .
Ndi dung phan tich trong pham vi nghien cflu gom cd: danh gid mflc do thay ddi gia tn edc he sd dn dmh trfldt va dn dmh ve sflc chiu t l i ciia n^n tai day tfldng cung nhflgia tri va diem ddt cfla thanh phan lflc ngang tai mat tudng qui Ude.
Cdbdntrfldng hop baitoan phan tich nhfl sau:
Bai toan 1: A n h h u d n g cOa goc ma sdt ngoai giCa dat dap va lUng t u d n g
Gia nguyen cac dai Ifldng trong m d hinh bdi toan phan tich, chi thay ddi gia tn gdc ma sat ngoai 5 (gdc ma sat gifla dat dap va lUng tUdng).
Phdn tieh cac ket q u i tinh toan khi 6 thay doi.
Bai t o l n 2: Anh hUdng ciia gdc nghieng m a t dat d a p
0 4 . 2 0 1 7 B f K i n t T l H V ! 1 ? Q
G i f l n g u y e n c d c d a i l f l o n g t r o n g m d h i n h b a i toan phdn tich, chi lhay ddi gia tn goc nghieng P eua be mat dat d i p so vdi phflong ngang. Phan tich c l e ket qua tinh todn khi p thay doi.
Bai toAn 3: Anh hUdng ciia cUdng do hoat tai tren mat dat dap Gifl nguyen cae dai IflOng trong md hinh bai toan phan tich, chl thay doi gid tri hoat tai q, tren be mat dat d i p Phan tieh cac ket qua tinh todn khi qi thay ddi
Bai toan 4: Anh hudng cua be rpng day tUdng B2 GiQ nguyen cac dai Iflong trong md hinh bai todn phdn tich, chi thay ddi gid tri kich thfldc be rdng day tfldng B2 Phan tich cdc ket qud tinh toan khi thay ddi B2.
3.2 Phan tich ket q u i thu dUdc tir cac bai toan dat ra 3.2.1 Bdi toan 1
Ket qua tinh toan thu duae nhfl trong bang l a va bang I b v d d d t h i quan he nhu the hien tr§n hinh 5a vd hinh Sb.
Bieu do qusD he giira S, P„, t
Bang1a:Hesd(FS)T, [FS)B khi thay ddi 6 Gia tri he so on A n h 6"
15°
17°
19°
21°
(FSh 1,20 1.23 1.27 1.30
{FS)B 1 63 1.82 2.02 2-24
B i n g l b Gia tri Pa,, z , e khi thay dot gde5 5"
15°
17°
19'
P»(kN) 254.01 250,10 246.28 21° 1 242,55
z(m) 2.76 2.76 2.76 2.76
e(m) 038 0.32 0 27 0 23
ID do quan lie giua 6 va (FS)j, (FS)B
15° n°
- * - ( F S ) T - . -(FS)S Hinh 5a; Bieu do quan he giOa fi va (FS)T, (FSls
276
* 254 01 2 76
I 250 10 2 76
•. 24628 2 76
1 242«
15° 19° 21°
- • - PaxOcN) -<i—zftn) Hinh 5b' Bieu do quan he giUa Pu, i theo 5 Nhan xet bai toan 1
- Gia t n gdc ma sat giQa Iflng tfldng vd dat dap (6) cd dnh hudng dSn he sd dn dinh (FS)T va hi sd (FS)B. Gid t n 5 cdng tang thi cac he sd 6n dlnti nay cdng tdng Tdc do tang ciia he sd (FS)B Idn hem nhieu so vdi toe do tang cua he sd (FS)T CU the trong pham vi phan tieh t h i y r i n g khi 6 tang t f l 15° den 21° thi (FS)B tdng 37,42% cdn (FShtdng 8,33%
- Thdnh phan lflc ngang P „ cd gia tri giam tuyen tinh theo sy tang cfla 6 vd diem dat gan nhu each day tfldng mdt gia tn khong ddi.
3.2.2 Bdi todn 2
Ket qua tinh toan thu dfldc nhfl trong b i n g 2a va bdng 2b; ddlt^
quan he the hien nhfltr§n hinh 6a va hinh 6b. ^ B i n g 2a: Hfe sd (F5)T, (FS)^ khi thay ddi
GidtrihSsodntfinh
P"
6°
8°
10°
12°
(FS)T 1.26 1.20 1.14 1.08
{FS)B 1.92 1.63 1.36 1.10
BSng 2b: Gia tri P^,, z va e khi thay ddi p
P"
6°
8°
10°
12°
P« (kN) 239 75 254.01 269,84 287.64
2{m) 2.72 2.76 2.80 2.83
e(m) : 0.33 ; 0.38 0,43 0.49 • Biea do quan ta^ ^ira p vk (FS)x, <FS}B
192
126 L63
1.20 114
1 10
I OS
,
- » - ( F S ) T - - * (FS)B Hinh 6a. Bieu (15 quan hegiBa p va [FS)i, (FS)B
310.00 300.00 2 9 0 0 0 280 00 270.00 260.00 2S0 00 240.00 230 00
f
11
± 239
Bilo do quan lie gllta ^ , P „ , z
2 8 0 ^ , . , ^ - '
2 J S , . - - ' ' ' ' ' ^
^ ^ - " " ' ^ 1 2 6 9 84
^ 254 0 ! 5
2 S3
i 287 64
to quan hf giira q, ^ „ , z
Hinh 6b: Bieu do quan he giiia PK, X theo p Nhan xet bai todn 2
- Od nghieng ciia mat dat d i p sau Iflng tfldng ed dnh hudng den gia tri h§ sd (FS)T va he sd {FS)a. Gia tn gdc p cang tang thi cac he sd dn dinh ndy cang gidm. Tdc dd giam cfla he sd (FS)B Idn hOn nhieu so vdi tdc dd g i l m cfla he so (FS)T. CU t h ^ trong pham vi phan tich thay r i n g khi p tdng t f l 6 ' ' d e n l 2 ° t h i ( F 5 ) e g i d m 42,7 % cdn (FSlrgiam 14,3%
- Thanh phan lflc ngang ?„, cd gia tn tang g i n tuyen tinh theo p va VI tri di^m d | t Pa each day tfldng khoang z cung tang theo p.
3.2.3 B l i toan 3
Ket qua tfnh todn thu dfloc the hien trong bang 3a va b i n g 3b; do thj quan hS t h ^ hien nhfl tren hinh 7a va 7b.
Bang 3a: He sd (FS)T. (FS)fl khi thay ddi q.
GiatrihSso^ndinh q>(T/m^)
2 2.2 2.4 2.6 2.8
(FS), 1.20 1.19 1.17 1.16 1.15
(FS)B 1.63 1 55 1.47 1.39 1.33 Bdng 3b: Gia tn P«, z va e khi thay ddi q^
q . ( T / m ' ) 2 2 2 2.4 2.6 2.8
P„(kN) 254.01 259.87 265.72 271.57 277 43
z(m) 2 76 2 78 2.80 2.82 2.84
e(m) 0 38 0,39 0.41 042 0.43
Bien dd quan be gii^a q, va (FS)7, (FS)B -.. 1-63
120 155
119 147
117 139
i-16 133
1.15
- • - ( F S ) T - * -(FS)B Hinh 7a Bieu do quan h§ giBa q,va (FS)r, (FS)s
2TS00 - 270 00 260 00
asooo 24000 23! 00 230 OD
r — - ^ n - 2 » « ) - - — ^ .31 Ui
""1 /
l^C
/
1• - , , \ .
fill
^^
• 2 94"'^
1 q.(T/==) -•-PnOtN) -a-iim)
Hirh 7b' 8ieu do quan h§ giiZa Pi^ z theo q^
Nhan xet bai todn 3
- Cfldng dd hoat tdi tren mat d i t d i p sau Iflng tfldng (q,) cd I n h hfldng d^n gia tri he sd dn dmh (FS)r va h^ sd (FS)B. Gid tri hoat tai q, cang tdng thi cac hi sd dn djnh nay cdng giam. Tdc dd g i l m ciia h6 sd (FS)B Idn hdn nhieu so vdi tdc dd giam cfla he sd (FS)r. Cu t h ^ trong pham vi phdn tich thay r i n g khi q , tang t f l 2,0 T / m ' d I n 2,8 T / m ' thi (FS)Bgilm 18,4 % cdn (FS)T gidm 4,2 %. IVlflc dd gidm cua (FS)T khdng ddng k^ theo sif tang gid tri q>.
- Gia tri vd diem dat thanh phan lUc ngang Pj, tang theo Sfl tdng cfla hoat tai qi.
3.2.4 Bdi toan 4
Ket qud tinh toan ghi trong bdng 4a va bang 4b, dd thi quan he nhfl tren hinh 8a va hinh 8b.
Bang 4a: H& sd (FS}T, (F5)8 khi thay ddi B2 Gia tri he soon dinh B,(m)
2.6 2.8 3 3.2 3 4
(F5)r 1 10 1 15 1.20 1.25 1.3
(FS)B 1.04 1.32 1.63 197 2.33 Bdng 4b: Gia tri P,,, z va e khi thay ddi B2
Bj(m) 2.6 2.8 3 3.2 3.4
Pax(kN) 250.62 252.31 25401 255.72 257.43
z(m) 2.74 2.75 2 76 2.77 2.78
e(m) 0.48 0.42 0.38 0.33 0.29
: BieaaaqaaBhepvaber9ngliidiigB2va(FS)7,(FS)B
•
1 J 2
lio . — M ^ — .
1-63 .
1 2 0 1,97 ^
125 13
26 27 28 29 3 3.1 32 33 34
Hmh 8a Bieu do quan he giBa B2 va (FS)T, (FS]«
i Bien do qnan he giira q, J „ , z 2'0
250 00 • 251
,
62 -
1 =^r-^ -
yf 1 1
-y^ 1
' ^ 1 i "" 1 1 '
2 4 2-6 2 8 3 i2 3 4 3 6 Brfm)
— P B * N ) - ^ I ( I I I ) Kmh 8b: Bieu dd quan he gii^ Pu, i theo B2 N h a n x e t bdi t o d n 4
- Kich thudc mdng tfldng B2 cd anh hfldng den gid tri he sd dn dinh (F5)r va h^ sd (FS)B Gia tn B2 cang tang thi cac he sd dn dmh nay cdng tdng.Tdcdgtangcua hesd(FS)B Idn honnhieusovdi tdc dd tang ciia he sd (FS)T, CU the trong pham vi phan tfch thay r i n g khi 62 tang tfl 2,6 m den 3,4 m thi {FS)Btang 124,0 % cdn (F5)[tang18,l %, Mdc do tang cfla (FS)fl la dang ke theo sfltang kich thfldc B2.
- Gid tn va diem dat cfla thdnh p h i n lUc ngang P„ eo tdng theo gia t n B2, tuy nhien gia tn Pa« tdng khdng ddng ke theo sutang cfla B2.
4 . K i T L U A N
Cdc he sd on dinh ddi vdi cdng trinh tfldng c h i n dang cdng - xdn phu thudc vao nhi^u yeu td khac nhau nhfl kich thfldc chdn tfldng, ma sat giiJ^ dat d i p va Iflng tudng, do nghieng ciia m a t d a t d a p v a c f l d n g d d hoat tai tren mat dat dap... Khi thay ddi cac yeu td tren nhdn thay r i n g tdc dd tang hoac giam ciia he sd (FS)B thucffig Idn hon nhieu so vdi tdc dd tdng hoac giam cfla he sd (FS)i. Oe tang them h& sd on dinh cho cdng trinh tUdng c h i n thi tang be rong day mdng tUdng se dat hieu qua cao hdn so vdi tang gidm ede yeu td khde. Gid tn vd diem dat cfla thanh phan lUc ngang Pu khdng phu thudc nhieu vdo sfl tang kich thfldc B2 cfla mdng tUdng chan dang cdng xdn
TAiUEUTHAMKHAO
[1] Ralphs Peck-WalterE Hanson-Thomas H.Thomburn Foundation Engineering 2'^ed.
NewYoik:Wiley,tl974
[21lvluni Budhu Soil Mechanics and Fondations 3'^ Edition, John Wiley & Son, 2011.
[3| Braja M. Das. Pnnciples of Foundation Engineenng Eighth Edition, Timothy L Anderson 2014
l42|BWifrii;(IB» 04.2017
