KHOA HOC VA CONG NGHE
NGHIEN ctru ANH HUONG CUA TY SO CO KET THEO PHUONG NGANG C^ VA PHUONG DUNG C^ (Ch/C^) DEN KET QUA TINH TOAN XU LY NEN DUONG DAP TREN DAT
YEU BANG THIET BI THOAT NUOC THANG DUNG
ThS. D 6 THANG Tru&ng DHDL Phucmg Ddng
GS.TS. VU DINH PHIJNG Trudng Dai hoc Xdy Dung
Abstract
Value of the ratio Cf^/C^ = mis the fundamental parameters affect greatly to the results of calculations process the road embankment on soft soils with Prefabricated Vertical Drain. According Bergado and Pham Van Long [6] when research soft soil in Bangkok (Thailand), the value of m can vary from 4 to 10. Since less experiment conditions direct determination of C^ and C^ should calculation process the road embank- ment on soft soil with the Prefabricated Vertical Drain in Vietnam always choose the value ofm In the range 2-5 [1]. The results of the author>s calculate that with different values ofm, the time of consolidation differ- ent considerably, which affects directly to arrange the spacing between Prefabricated Vertical Drain, pulled by the cost to treat the soft soil.
Tom t i t
Trj so cua ty so'C^C^m la thdng so'cabin anh hudng rat l&n den ket qua tinh toan khl xii ly nen dudng dap tren da't ye'u bang thiet bj thoat nu&c thing du'ng. Theo Bergado va Pham Van Long [6] khi nghien ciiu dat yeu Bangkok (Thai Lan) thi gia trj cua m cd the bien doi tir 4 den 10. Vi ft cd dieu kien thf nghiem xac djnh true tie'p C^ va C^ nen trong tfnh toan xii ly nen da't yeu bang thiei bj thoat nu&c thing dung d Viet Nam thu&ng lua chgn gia trj etja m nam trong khoang 2-5 [1]. Cac ket qua tfnh toan ciia tae gia cho thay v&i eae gia trj ciia m khae nhau thi th&i gian edket khae nhau dang ke, dieu nay anh hudng true tiep den viec bo trf khoang each giu'a cac bae tha'm, keo theo dd la chi phf de xU ly nen da't ye'u.
Tfnh toan xCr ly nen dat yeu bang bae tham thl viec trong 2 thang ve dp lun, yeu cau moi thang dp lun khdng che dp lun la yeu cau bat budc. Trong tieu khdng vupt qua 5mm, thoa man yeu cau tren mdi chuan 22TCN262-2000 cua Viet Nam [1] khdng che dupe dd tai dao dudng va bat dau cho phep rai mat dp cd ke't dat dupe trudc khi xay dung ke't cau ao dudng. VI vay tac gia kien nghi khi thiet ke xtr ly nen dudng la 90%. Ne'u tuan thu theo yeu cau nay thl dp da't yeu bang thiet bj thoat nude dQng thl phai thoa lun du cho phep trong thdi gian van hanh se bao gdm man ddng thdi ca hai yeu td: Dd lun cdn lai sau thi 10% dp lun cd ket sa cap va toan bd dp lun cd ket thQ edng va toe do lun theo th&i gian rai mat du&ng nhu cap. Op lun du nay cd t h l len de'n han 30 % dp lun sa tieu chuan JTGD30-2004 cua Trung Quoc. Vdi yeu cap SJ;, va cd t h l xay ra chi trong thdi gian tQ 10 de'n cau nay thi tdc dp lun nhQng nam dau ludn < 2cm/nam 20 nam vdi tdc dp lun du trong nhQng nam dau Idn hoan toan thoa man khi sQ dung mat dudng cap han 2cm/nam. Trong tieu chuan JTGD30-2004 cua c a o A I .
Trung Qud'c [2] cdng tac rai mat dudng phai tie'n hanh - p . _ ' , , u - i , - . » - i - t , , * - *- - .»•
^ ., J Tren cd sd khong che dp lun nhu tren tac gia di sau khi dd lun cua nen dudng da dn dinh, su'dung hai .. . . • . u ' - i, «;5^ t,^'^ • ! , - „ * * .A,
^- ^ .? ^^'^^ *°="'' khoang cach cam bac tham trong truang tieu chuan de khdng che cu t h l la yeu cau tfnh toan . ^ . . - „ r« /o *i,....^^n.-,n c .-^ A- • u "
^ , ' , ^^^P he so m=C(^/Cv thay doi t u 2-5 ung vai cac chieu ve dd lun sau thi cdng phai nhd han so vdi gia tri thiet ^^ ., ^ J - * - , / i Hr>,v, O X I ; A . . ^ ' • u
^ ^ a • cao dap thay doi t u 4-1 Om. So lieu dau vao nhu sau:
ke cho phep, ddng thdi yeu cau phai quan sat lien tuc
TAP CHi CAU D U d N G VIET NAM
KHOA HOC VA CONG NGHE
Dudng cap I, tdc dp thiet ke 80km/h, be rdng nen dudng Bn4n=29m, taluy dap 1/m=1/1.5, dung trpng dat dap y=19kN/m^ be day Idp dat ye'u H=15m, he sd rdng eo=1.5, he sd c d ket theo phuang dQng Cv=0.5.10-3cmVs, ap luc tien cd ke't ap=0.06MPa, muc nudc ngam ngay tai mat dat tu nhien, dung trpng day ndi Y(3n=6kN/m^ chT sd nen 0^=0.5, chi sd nd Cr=0.05.
Tac gia da sis dung phan mem Excel d l lap bang tfnh toan vdi 49 trudng hpp tQ sd lieu dau vao tren.
Ket qua tfnh toan tdng hop d bang 1 (chi tie't tfnh toan [8] phu luc 5)
Bang 1. Khoang each giira eae ba'c tham Ichi Cf/C^^2-5 tmg vdi ehieu eao dap thay doi
K/cPVD
C,/C.
4 5 6 7 8 9 10
Kho^g c^cti gioa cSc bic Ihlm (m)
2
1.31 1.28 1.25 1.23 1.22 1.21 1,20
2.5
1.38 1.34 131 1.30 1.28 1.27 1.26
3
1.43 1.39 1,36 1.34 1.33 1.32 1,31
3,5
1.48 1,43 1.41 1,39 1,37 1.36 1,35
4
1,51 1,47 1,44 1,42 1,40 1.39 1,38
4.5
1,55 1,50 1,47 1,45 1.43 1,42 1.41
5
1,57 1.52 1.49 1,47 1,45 1,44 1,43
1,80 165 150 145 140 135 1,30 126 120
^ ^^
^'
w
"C^
^ v ^ ^
-^
gsS^'
^
^^^^^5^
....^ "
^-^*=S rf^-'
^__^
=5S& * t j - i l m - • - _ H=5m
H=6m ... .. H=7m - • - H = a m - « — H = 9 m
— H=10m
Ty sO' C./ C,
Hinh 1. Bieu do khoing each giifa cac bac tha'm khi Cf/C^2-5 irng vai ehieu eao dap thay ddi
Tu sO' lieu tdng hpp trong bang 1 ta tha'y khi chpn ty sd m=5 tiet kiem han so vdi viec chpn m=2 lupng bac tham tren 40%. Vdi dan gia tai Ha Ndi hien nay la 721.000d/100m dai bac tham thi mdi km dudng nhu tren tiet kiem duac 860 trieu ddng tQc la mdi met nen dudng tiet kiem gan 1 trieu ddng. Vdi each tfnh toan nhu tren thi viec xac djnh xac djnh chfnh xac ty sd m la rat can thiet anh hudng true tie'p tdi chi phf xay
dung dudng.
Trong luan an Tie'n sy dja chat eua NCS Nguyen Manh Thuy dudi su hudng dan cua GS.TSKH. Pham Van Ty [9] da tfnh toan xac djnh dupc ty sd m=Ch/Cv nam trong khoang tQ 4-12, trong khoang tQ 6-7 cd mQc sai sd tuang ddi nhd nhat tQ sd lieu quan trac ap luc nudc Id rdng du tai "Trung tam thuang mai Phu Lam" thanh phd Hd Chf Minh. Oieu nay chQng td trong thie't ke hien nay d l thien ve an toan chung ta thudng lay trj sd m= 2 do khdng xac dinh dupe chfnh xac ty sd m gay lang phf rat Idn. Do dd vdi cdng trinh dudng cd xCr ly b i n g thiet bj thoat nudc thang dQng thl viec do ap luc nudc Id rdng d u tai doan dap thCr nghiem la yeu cau b i t bupc tren ca sd dd xac djnh dupc he sd m.
Ket luan va kie'n nghj
Viec xae djnh chfnh xac ty sd cd ket theo phuang ngang Ch va phuang dQng C^ la van de kinh te ky thuat anh hudng true tiep den chi phf xay xCr ly nen da't yeu bang thiet bj thoat nudc thang dQng. VI vay tren cac doan dap thQ nghiem can cd thiet bj do ap luc nudc Id rdng du de tQ dd xac djnh dupc chinh xac ty sd m=Ch/Cv •
TAI LIEU THAM KHAO
1. 22TCN-262 - 2000. Quy trinh khao sat thiet ke nen du&ng dtd dip tren dat yeu. Nha xuat ban Giao thdng van tai. Ha Ndi - 2001.
2. JTG D30-2004. Quy trinh thiet ke nen du&ng.
Bd giao thdng nude CHND Trung Hoa ban hanh - 2004.
3. JTJOl7-96. Quy pham thiet ke va thi cdng nen du&ng dap tren dat mem yeu. Bp giao thdng nudc CHND Trung Hoa ban hanh -1996.
4. PGS. TS. Nguyen Ngpc Bfeh, Th.S. Le Thj Thanh Binh, PGS. TS. Vu Dinh Phung. Dat xay dung, dja chat cdng trinh va ky thuat cai tao dat trong xay dung. Nha xuat ban Xay dung, Ha Ndi - 2005.
(Xem tiep trang 26)
TAP CHi CAU DUdNG VIET NAM
KHOA HOC VA CONG NGHE
• Viec Qng dung thQ nghiem loai be tdng nay la can thiet nham da dang hoa cac loai hinh vat lieu va ket cau trong xay dung, nhat la xay dung cdng trinh giao thdng •
NGHIEN CUU ANH HUONG CUA
(Tiep theo trang 21)
TAI LIEU THAM KHAO
1. Dao Van Ddng (2009). Vat lieu "xanh" va ben vOng - xu hudng de phat trien xay dung, Tap chf Khoa hpc cdng nghe Xay dung.
2. Dao Van Ddng (2009). VOa va be tdng "xanh"
SLf dung chat ket dinh polyme vd ca. Tap ehi Khoa hgc GTVT.
3. Joseph Davidovits (2002). 30 years of success- es and failures in geopolymer application.
4. Dao Van Ddng (2010). Nghien cu'u iing xii nen va keo khi ud'n eua vu'a polyme vd ca. Tap chi GTVT.
5. ASTM C192 (2007). Standard Practice for mak- ing and curing concrete test specimens in the labora- tory. American Society for Testing and Materials.
6. ASTM C39 (2005). Standard test method for compressive strength of cylindrical concrete speci- mens. American Society for Testing and Materials.
7. TCVN 3119 (1993). Be tdng nang - Phuang phap xac djnh cudng do keo khl ud'n. Tuyen tip tieu chuan xay dung Viet Nam.
8. Departments of the Army and the Air Force (1987). Standard Practice for concrete pavements.
America.
9. ASTM C496 (2004). Standard test method for spiitting tensile strength of cylindrical concrete speei- nwns. American Society for Testing and Materials.
AO. Neville A. M. (2000). Properties of concrete.
Prentice Hall.
11. ASTM C469 (2002). Standard test method for static modulus of elasticity and poisson>s ratio of con- crete in compression. American Society for Testing and Materials.
5. Ly Chuang Minh. Ly luan, thiet ke, thi cdng gia cd nen da't yeu. Nha xuat ban Oien luc Bac Kinh - 2006, ban djch Tieng Viet cQa Nguyen Soan
6. Pham Van Long & D.T. Bergado. Thiet ke xii ly nen da't yeu bang chat tai trudc ket hap v&i thoat nudc diing. Tap chi cau dudng, sd 7 thang 10 - 1997.
7. GS. TS. VQ Olnh Phung, Th.S. Vu Qudc Cudng.
Cdng nghe va vat lieu m&i trong xay dung dudng. Nha xuat ban Xay duii^. Ha Ndi - 2005.
8. Do Thang. Luan van Thac sy ky thuat "Nghien Cliu phuang phap tfnh toan xii ly nen u&ng dap tren da't yeu bang thiet bj thoat nudc thing du'ng cua tieu chuan Viet Nam 22TCN262-2000 va tieu chuan JTGD30-2004 eua Trung Qude". Dai hpc Xay dung.
Ha Ndi 6-2008, dudi su hudng d i n cua GS. TS. Vu Olnh Phung.
9. Nguyen Manh Thuy. Luan an tien sy dja chat"
Lua chgn giai phap ky thuat hap ly xii ly nen da't yeu dkhu vuc phia nam thanh phd Ho Chi Minh". Oai hpc Md- Oja chat, Ha Npi - 2002, dudi du hudng d i n cua GS. TSKH. Pham Van Ty.
Tieng Anh
10. Brajam.Das The University of Texas at EL Pasp. Advanced Soil Mechanics. Hemisphere Publisishing Corporation Washington - New York - London.
11. Geotechnical Engineering circular N^ 5. FHWA - I F - 0 2 - 0 3 4 .
12. Yongyuth Taesiri, Tawee Gasisamang, Poranic Jitareekul, Pitisak Chantaranimi. An Enginerring Manual for Embankment Settlement Estimation. Bureau of Materials, Research and Development Department of Highways, July 19, 2002.
TAP CHI CAU DLTdNG VIET NAM
