AlW miDNG COA M O T so Kfr CAU GIA T M G BO c u m BBV KHA NANG K H i ^ TWO PHUDNG NGANG CUA BAP B£ T D N G TRU CHONG
Nguyen Ngoe Thang'
Tdm tat: Ddp hogc tu&ng chan cd tru chdng Id dgng kit cdu dugc su dung rpng rdi trong cdc cdng trinh thuy lgi, thuy dien. Ket cdu dgng ndy co dp mdnh l&n theo phuong ngang nen khd ndng cua chung chiu tdi trgng, ddc biet la tdi trgng dgng (heo phuang ndy kem hon so v&i khi chiu (di trgng theo cdc phuong khdc. Npi dung cua bdi bdo ndy di sdu vdo phdn tich dnh hu&ng cua mgt sd ket cdu gia tdng dp cung din khd ndng khdng chdn theo phuong ngang cua dap be tdng tru chdng.
Tu* khda: Dgp tru chong, dp cirng, dpng ddt, khdng chdn, irng sudt, phuong ngang 1. Cac ket cau gia tang do cirng theo
phirong ngang cua dap tru chong [1, 3|
Tai cac khu vuc cd nguy ca ddng dil, dd tang kha nang chiu tai trpng theo phuang ngang (phuang tuyen dap) ctia dap try chong, ngudi ta bd tri cac ket cau gia tang dp cung theo phuong nay dudi dang tudng, try chdng kep, thanh giing (khi khau do khdng qua Idn va try chdng mdng) hoac cac vach cung trong trudng hgp h-y chdng rdng. Sy can thiet ciia vide bd tri cac ket cau gia tang dp cdng phy thudc vao cac dieu ki?n thyc te cua cdng trinh (chieu cao cua dap, chieu day ciia try chdng, boat ddng dja chan cua viing xay dyng cdng trinh....). Cac sudn va vach cimg thudng bd tri theo phuang thang dimg ho^c song song vdi mai ha ciia try chdng.
Cac thanh giang thang (dam giang) Ihudng bd tri thanh cac hang song song vdi mai ba cua try chdng. Lien ket giua thanh giing va try chdng thudng la lien ket ngam hoSc Hen ket khdp. Neu mai thugng Iuu dugc chia thanh limg khoang, nen bd tri lien kel khdp gitra thanh giang va try chdng. Cac thanh giang cd the thang (dam giing) hoac cong (vdm giing). Trong mdt khoang, ngudi la bd tri hoac loan bd dam giang hoac toan bd vdm giang.
Npi dung bai bao trinh bay ket qua nghien cdu va so sanh anh hudng ciia kdt cau gia lang dp cung theo phuang ngang dudi dang dam giing, vdm giing den kha nang khang chan (trang thai ung suat - bien dang) cua dap be
Dgi hgc Thuy lgi
tdng try chdng. Cac ket cdu dugc tinh toan bang phan mem tinh ket cau SAP2000 v. 14 theo md hinh khdng gian.
2.Sa do va cac tru-dng hpp tinh toan Xet md hinh dap try chdng lam viec ddng Ihdi vdi ndn cd cac thdng sd hinh hpc nhu sau:
dap cao 32 m; he sd mai thugng va ha luu mi = m2 = 0,5; try chdng cd dang tam giac va dap gdm 6 try; ban mat chan nudc day 3m; try chdng day 2 m; khoang each giiJa tim 2 try bing lOm; chieu dai ndn trudc va sau dap theo phuang ddng chay lay bing 70m; chieu sau nen tinh toan bang 70m; myc nudc thugng luu 32 m, ha Iuu khdng cd nudc.
Ngoai ra, viec nghidn ciru trang thai ung suat - bien dang cung dugc lien hanh vdi hai md hinh dap Iru chdng cd cting kich thudc nhu tren nhung cd bd sung Ihem cac ket cau gia tang dp cung theo phuang ngang la vdm giang va dam giang lam ttr cimg mdt loai vat Heu vdi than dap.
Kich thudc mat cat ngang ciia dam giang va vdm giang bang 30 cm x 30 cm.
De don gian Irong linh toan, ta coi vai lieu lam dap va nen lam viec trong mien dan hdi. Be long lam dap cd mac Ml 50, trpng Iugng rieng ciia be tdng f^^24kN/m , md dun dan hdi Eb=2,5.I0' kWW, he sd poisson Ub=0,2. Nen da cd md dun dan hdi En=5.I0'' kN/m^, trpng lugng rieng y^ =26,8 kN/m^, Un =0,2; he sd ma sat (p=0,75; lyc dinh c = 150 kN/ml
Ket cau cdng Irinh cd ke den tai trpng dpng dit dugc tinh toan vdi vdi hai td hgp tai trgng sau:
KHOA HQC KV T H U A T THUY LQI VA M O I TRl^WG • S6 43 (12/2013)
a. Truong hgp 1 - Td hgp tdi trgng co bdn:
+ Trgng lugng ban than dap;
+ Thugng luu cd nudc, Hn = 32 m;
+ Ha luu khdng cd nudc;
+ Ap lyc tham.
b. Tru&ng hgp 2 - T6 hgp tdi trgng dgc biet:
+ Trpng lupng ban than dap + Thugng luu cd nudc, Hti = 32 m;
+ Ha luu khdng cd nudc;
+ Ap lyc tham;
1- Dpng dit cap 8; su dung phd dgng dit ciia Trung Qudc Chinese 2002.
Md hinh dap try chdng dugc tinh toan chiu anh hudng ddng dat theo hai phuang chinh: dpc theo tuydn dap va Iheo phuang ddng chay. Gia ldc Iheo phucmg diing dugc lay bang mdt phan ba gia tdc theo phuang nam ngang.
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Hinh 1. So do tinh ddp iru chdng co ke't cdu gia tdng dp cdng theo phuc/ng ngang So dd bd tri cac diem linh toan kiem tra cho tren hinh 2, md hinh phan dap dugc the hien ro Iren hinh 3. Kdt qua linh loan ung suat va chuyen vi Irong than dap dugc the hien qua cac bang I va 2.
.Hinh 2. Sa do cdc diem kiem tra irons thdn dap IT un x^-1^ i-n.- i- J - .-. uA«n
^ • '^ Hinh 3. Mo hmh khong gian phan dgp tru chong
KHOA HQC K? T H U A T THtJY LQI VA H 6 I TRUdWC - S6 43 (12/2013)
Bdng 1. Kel qud linh dng sudt igi cdc diem kiem tra
«^
1 L'og (kN m:)
V, 0, 0 , o.
c.
c.
o .
"!
a.
o.
Ov a.
0 . -" c.
O l Oi l y 0 ,
Khon; CO g i i s ;
Tmh
-829.16 -210 93 -15-1B.05 90 36
• 5 2 J 0 -205 77 -27-05 20 98 -35 98 -10 27 -2 85 - 3 ! 18 -fill 26 25 97 -599.02 -193.72 -90 10 -1151 84
Dpng dai theo phucmg
dong chay -480.08 -129.05 -936.60 231.43 56 69 163.24 -12-12 37 78 -27.53 -7.75 -2-17 -22.98 -543.87 35 iS -556 93 -163-83 -73 48 -1046.34
D^ag dat theo phuoag
n j \ e n d j p -734 46 -1S3 63 -1037,94 110 96 -37-30 -143 77 -12 07 S8S3 -16,55 78 96 3.44 61.67 -483 16 40 16 -536 72 -188.00 -77.83 -1067 12
Co dim giing
Tmh
-S29-SS -211.24 -1550.28 91.80 -52 70 -205 30 -27 37 2 1 3 4 -35 19 -1041 -2.96 -31 72 -591 00 26 36 -590 84 -177=2 -96.26 -1169 72
D ^ g d3I theo phuotig
dong chi%
-480,25 -129.16 -937.01 281 66
56 58 163.52 -12.34 38-79 -27 60 -7.94 -2-25 -23 33 -540 03 38-28
•556.79 -134 69
•34-01 -1075 13
Dgng dat ihco phuong
-73S.17 - ! « . 7 9 -1037 82 11146
•37.38 -142 20 -12 60 89 70 -16.92 7S01 3 31 60 00 -473 97 42-19 -535 SS -163 SO 89 62 -1107 03
Co vom p i n g
Tmh
-829.79 -211.19 -1549.85 91 39 -52.88 -205 34 -27 17 19 65 -35 94 -15 27 -2.42 -35 61 -633 46 26 42 -606 98 -200 59 -S9S0 -1148 75
Dong dat theo phuang
-W0 3«
-129 19 -937 51 2S1 -IS 56 66
!63 32 -12 38 37 28 -27.60 -"92 -2 23 -23 54 -541 25 35 47 -556 28 -134 4S -S4 25 -1076 SO
D9Qg dat theo phuong
tuyen dap - 7 J S J 0 -164 00
•1041-24 110 90 - 3 " 3 : -142.94 -12J10 88 70 -17.05 7VS0 5 33 59 96 -495 25 39 04 -525.58 -1:3 "fS
•SS07 -1113 04
Bang 2. Gid tri ung sudt vd chuyen vi l&n nhdl trong than dgp
Dang ket c i u
Khdng giing
C o d k i giing
Co vdm
Ttuong htrp tinh
K h 6 n g c 6 t f $ n B < l i l Dpng dat theo phumig dong cha\
D ^ n g dai theo phutmg tuyen d i p K h S n g c o t l d n g d i t D^ng dai tbeo phiicmgdong chav
D^ng dat theo phticftig tuviti d j p Khdng CO dOng 6il
Dpng d l t theo phuong dong chay
D $ n g dat theo phinmg tuy^n d j p
f n g suit trong than dap fkN tn-) o . m a x
441.75 : S 2 . S 3 139 99 392.02 281.99 140.47 3 7 4 . I S 281-SS 140.05
c , m m -829.35 -1132 79
• 1009.13 -830.08 -1182 39 -1004.15
-829.98 -1182.32 -1009.27
c m a x 245 14 277 SO 218.16 247 39 252 67 216.33 244.21 254.29 218 33
Cimin -358.96 -401-28 -422.23 -359.52 -401-31 -418.25 -359.25 -401 29 -422 08
c . m a s 588 60
^ 302 54 145 21 570-81 302 75 143.83 558 63 303-22 145.35
c , m m -1708.21 -2323-96 -730.57 -1646,84 -2323 23
• 730.38 -1646.37 -2320-23 -730.73
Chu> en \-| lon nhat trong tlian dap (m) U > m a \ 0.000958 0 001806 0.001128 0.000958 0 001804 0.001128 0.000958 0 001904 0.001128
Ujraax 0.000062 0 000067 0-001512 0-000062 0.000067 0.001463 0.000062 0.000067 0-001520
Ujma.t 0 003698 0 003729 0 003700 0 003698 0 003729 0.003700 0.003698 0 003729 0 003700
3. Nhan xet ket qua tinh toan
Kk qua nghien ciru anh hucmg ciia cac ket c4u gia tang do cirng dSn cac dac trung dong lire hpc cua dap try chSng da duac dk cap den trong [4]. K6t qua nghien cuu trang thai img suat - biSn dang cua h$ "dap tru chong - nen da" cho thay cac gia trj iing suAt lon nhat xuat hien chu ySu t?i cac v| tri tren try ch6ng. Khi co dong dat, ijmg suSt va chuyto vj trong than dap thay doi kha ra r?t, diSu nay mpt lin nira chimg to dpng
djt anh huong rit Icjn den cong trinh xay dung.
Khi CO dpng dit, chuyen vi theo phucmg thang dimg thay doi khong nhieu. Khi co dong dat theo phucmg dong chay, chuyen vi tang 90%
theo phuang dong chay, khoang 8% theo phuong tuySn dap, con theo phuong thing dimg chuy6n vi thay doi khong dang ke. Khi c6 dpng dat theo phucmg tuyen dap, chuyen vj tang 18%
Iheo phucmg dong chay, theo phuang dong chay chuySn vj thay doi khong dang ke, nhung d5c
KHOA HQC K» THUAT THUY L?! VA Mfll TRlrtNC - S6 43 (12/2013)
biet tang gkn 25 lln theo phucmg tuyen dap.
Di^u nay xay ra do do cung theo phucmg tuyen dap nho hcm nhi^u so vai do cung theo phuang dong chay. No cung noi den sir can thiet phai gia tang dp cung theo phucmg ngang khi xay dung dap tru chong trong vung co dong dat.
Trong tat ca cac trucmg hcrp tinh toan, vung nguy hiem trong than dap la khu vuc nam a tru chong, trong khoang 1/3 chieu cao dap ke tir chan dap. Ket qua tinh toan on dinh chong trucrt cung cho thay mo hinh dap tru chong dam bao on dinh khi c6 dong dat cap 8. Khi co dong dat theo phuang dong chay, he so on dinh chong trugt ciia dap theo phuang nay khi khong co giang va khi co giang gia tang do ciing thay doi khong nhieu. Khi co dong dat theo phucmg tuyen dap (phuang ngang), he so on dinh trong truang hgp dap co vom giang cao han so \'ai hai truang hgp con lai. Dieu nay chiing to kha nang khang chan theo phuang ngang dugc cai thien
tot hcm khi dap dugc bo sung cac giang ciing dang cong.
4. Ket luan
Doi voi nhung ket cau co kha nang chiu tai trong theo phuang ngang (phuang tuyen dap) khong tot nhu dap hay tuang chan co tru ch6ng, viec bo tri cac ket cau gia tang do ciing theo phuang nay la rat can thiet, dac biet khi cong trinh nam trong vimg co kha nang xuat hien dgng dat. Co rat nhieu ket cau dugc sii dung voi muc dich nay nhu tuong, vach, thanh giang...
Trong truong hgp cong trinh dugc bo sung thanh giang nham tang kha nang khang chan, neu dieu kien cho phep, nen sir dung cac thanh giang CO dang cong vi chiing lam giam iing suat trong than dap khi co dong dat tot ban so voi cac thanh giang thang. Viec lua chon so lucmg, kich thuac, hinh dang cac thanh giang can duoc nghien ciiu ky cang doi voi timg cong trinh cu thd.
TAI LIEU THAM KHAO
1. Ngo Tri Vieng. So tay kf thudl thuy lgi tap 2. NXB Xay dung.
2. Nguyin Le Ninh (2007), Dgng ddt vd thiit ki cdng trinh chju dpng ddt, NXB Xay dung.
3. Grishin M.M., Rozanov N.P va nnk, Dgp be long tren nin da. NXB Xay dung. Moscow, 1974 (ban tiSng Nga).
4. Nguyen Nggc Thang. Anh hu&ng cua mot sd dgng kit cdu gia (dng dp cung din cdc dqc (rung dpng lice hoc ciia dgp be tdng (ru dhdng. Tap chi Khoa hgc ky thuat Thiiy loi va Moi truang s6 42 (9/2013), tr. 100.
Summary
INFLUENCE OF SOME RIGIDITY-INCREASED STRUCTURES TO THE SEISMIC STABILITY OF THE CONCRETE BUTTRESS DAMS
The buKress dams or abutmen{ walls are slender structures in the line ofdamsite, so their ability to work under load, especially under seismic load in (his direcdon is less effecdve (han other directions. Therefore, (he rigidity increasing of buttress dams in the line ofdamsite significantly improves their .seismic resistance. This paper includes the analysis ofthe influence of some rigidity- increa.sed s(ruc(ures like beams, arches, (o (he seismic stability ofthe concrete buttress dams
Keyword: buttress dam, earthquake, seismic stability.
Ngu&i phdn bi^n: PGS. TS. Nguyen Quang Cu-frng BBT nhdn bdi. 5/11/2013 Phdn bien xong: 27/12/2013
KHOA Hpc K? T H U A T THUY LQI VA M O I TRlT^fNG - S6 43 (12/2013)
