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M6 phong chuyen djch cua dat nen tren mat dit khi ep coc be tong bang phan mem Plaxis 8.5
Ngay nhan bai: 15/11/2014 Ngay su^ bai: 22/11/2014 Ngay chap nhan dang: 5/12/2014
Le Van Pha, Dang Hu'ng Thanh
T O M TAT:
Trong thilc te xay ddng hien nay, mong coc dang la giai phap difdc Ilia chon pho bien doi vdi cac cong trinh co tai trgng vila va 16n xay dUng trong khu vilc do thi do co nhiJng liu diem nhU, thi cfing nhanh, silc chiu tai cao, gia thanh phu hcfp, co the kiem soat diioc chat liiong tiing coc. Tuy nhien, ngoai cac ilu diem noi troi, phddng phap ep tinh coc van co the gay nen sii chuyen dich d^t trong qua trinh coc chi^m cho. Cac bieu hien c6 the thay diidc nhu hien tUang dat troi tren mat hoac gay anh hiicfng nha lien ke...
Phiidng phap dU bao pham vi viing anh hitdng va mile do chuyen dich dat khi ep coc hang phan mem Plaxis 8.5 co the dddc ap dung d^ de ra bien phap khac phuc nhiing anh hUdng bait ldi cua viec ep coc den cong trinh lan can, gop phan lam hoan thien hdn phdong phap ep coc trong dieu kien xay chen trong do thl hien nay.
ABSTRACT
In the current situation of the construction sector, pile foundation is a common choice for medium and high-load works constructed in the urban area thanks to its advantages such as quick construction, high load bearing capacity, reasonable price and possible quality control for each pile. However, in addition to its outstanding advantages, static pde stressing method can still result in soil movement m the pile occupation process. Visible phenomena are protrusion of soil on the surface or impact on adjacent houses, etc.
The method on forecasting the scale of affected area and soil movement level when pressing piles with Plaxis 8.5 software can be applied to work out measures to overcome adverse effects of the pile pressing on adjacent works, making contribution to the completion of the pile pressing method in the condition of adjacent construction in urban area nowadays.
Le Van Pha
Tong Cong Ty Cd Khi GTVT Sai Gon (SAMCO) D^ng Hirng Thanh
Triicfng Dai Hoc Bach Khoa TP HCM
l . T o n g quan
NhCmg cong bd v e s u x a o Iron va bien dang cua dat nen g i n coc da CO tir kha sdm.Theo De Mello (1969), Khi ep coc x u dng thi mpt lUOng the tich dat b\ dich chuyen, the tich khoi dat nay b i n g vdi the tich cua coc da chiem cho, dat bi dich chuyen theo cac hUdng, mot p h i n trong so dat hi dich chuyen len phia tren, bc(i vi dat it bi can trcf theo hUdng nay. Chuyen VI theo phuong thang dung cua dat trgn be mat dUOc goi la hien tUOng troi dat Vung chiu anh h u d n g nhieu nhat cua dat tap t r u n g chCi yeu d khu vUc sat than coc va gan mat d a t
Co che bien dang duoc m o ta b6i IVlassarsch (1974), Gan mat dat, su di chuyen ciia dat hau nhU la chuyen dong vdng, d o lUc dinh giCta dat va coc. Hinh thilc chuyen vi dan thay doi Ichi do sau ha coc tang them. SU dich chuyen ttd nen chCi yeu la chuyen vi ngang.
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H i r h l Chuyen dich flat khi ep coc
2. tA6 ph6ng ep coc bang p h i n m e m plaxis 8.5
Viec m o p h o n g ep tTnh coc duoc Ihuc hien t u o n g t u nhU cong tac thi cong tai hign trUdng. Tai t r o n g ep duoc thay the bang chuyen vi cUdng
Coctr^nmataiit &Kcia6Hu3m CocdSosaulSm Kinh 2 Mo phong qua Hinh ep coc bang plaxis S.5
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JMm) Hlnh 3:Chuyen vi dilng tai mat Oat Hinh4: Cliuyen vi ngang tai mat dat
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Kinh 5' So sanh chuyen vi dung Hinh 6: So sanh chuyen vi ngang
biJc theo phuong d i i n g , gia tri chuyen vi cudng bi?c nay 1^ I m , bang vdi d o dai cho moi hanh trinh cCia mSy ^p coc thuc te. Bh\ tohn dagc lap lai nhieu lan cho den khi dat do sau thiet ke, Cac thong s6 gia djnh khi Ichai bao trong bai t o^ n nhu sau:
- Ap dung bh\ tohn ddi xifng true -SCf dung coc vuong D=0 6m, Chieu sau ep coc L= 18m
- Nen m o t Idp, cac t h d n g sd dja chat theo tieu chuan Mohr-Coulomb, vdi: E'= 18.000 kPa, c'= 66 kPa, v'= H " , v = 0.3, ysat =20 kN/m*, Vunsat=18kN/m^
K^t quh chuyen vi tai d i l m each coc 1 D flifoc bi^u d i l n bSng d o thi nhusau:
M6 p h i n g dUOc thu'c hien cho cac diem co Itlioang c^ch tfnh tir coc t i r 1D den 4D
3. Nhan x^t va ket luan:
Khi vda m d i ep coc xuong do sau dudi 5D (D: dudng kfnh coc), chuyen vi tren mat dat theo ei hai phuang difng va ngang tang nhanh. Khi Il6sau q u ^ 5D den 15D, chuydn vj tang rat cham Va hau n h u khong thay sU thay doi dang ke nao Wii do shu ip coc vUOt qua 20 D (hinh 3-6). Ket quii nay cho thay chi can co bien phap ha coc phiJ hop trong giai doan ti^ lOc coc bat dau duoc ha xuong dat d e n d 6 s^u 20D Qua d o sau nay, coc ^p khflng con gay hnh hudng len mat dat.
Diem CO chuyen djch dat Idn nhat tap trung trong doan I D tinh tif mep coc vh gihm nhanh khi khoang each >3D (hinh 5,6). Do do, viec ap dung pho bien Ithoang each 3D khi bo t r i eoc vOi coc trong nhom nhU hien nay la phu hop.
Tuy nhien, vi ly d o an loan, ddi vdi loai dat hat mjn da c6 shn d o nen chat cao, khoang each bo trf coc xa han cung can dUoc xem xet Ngoai ra, de han che anh hu6ng den edng trinh lien ke, nen bd t r i coc each ranh dat khoang each >5D Can xem xet trang thai va loai dat de xac dinh khoang each cu the.
T&l Lllu THAM KHAO
1, Shamsher Prakash- Han D Shamia. Mong coc trong thuc texay dung Nha xuat ban Xay DUng, 1999
2. K Rainer Massarsch Soil movements caused by pile driving in day Sweden, Stockholm: Royal Swedish academy of engineering sciences, 1976.
