Sử dụng trường ứng suất phần tử hữu hạn tính toán hệ số an toàn ổn định mái đất

SCf DUNG TRI/ONG UNG SUAT PHAN TCT HOfU HAN

TfNH TOAN H£ S 6 AN TOAN 6 N OINH MAI DAT

TS. Nguyin Bio Viet

Khoa XSy dt/ng Ciu dudng

Trudng Dai hgc XSy dgng

Tdm tat: Trugt Id dit IS hidn tugng mdt khdi dit dS nSm trdn mdt mSi ddc

bj djch chuyin do cd sg phS hogi dgc theo mdt mSt trugt nSo dd trong mSi doe.

ThiSt hgi vi vSt chit vS con ngudi IS rit Idn vS khdng thd ludng duge. Hidn nay

vi$c phSn tich tinh toSn Pn dinh mSi dit hiu hit ddu dugc thu-e hidn bing eSc

phuong phSp truyin thing nhu phuong phSp Bishop. CSc phuong phSp nSy ddu

dugc xSy dung trdn co sd cOa ly thuyit cSn bSng gidi h^n, do dd nd khdng xdt

din dugc mdt si yiu td nhu modul bidn dang E, hd s6 poatxong p, h$ sd dp /uc

tTnh Ko. Vdi vipc phSn tich sg phSn phPi ung suit trong dit bSng phuong phip

phin tif hCru hgn vS tinh toSn h$ sd an toSn tdng thi trdn trudng ung suit nSy.

cSc yiu tP mS cSc phuong phSp truydn thing khdng thi xdt din dugc sd dutyc

dua vSo trong tinh todn. Kit quS tinh toSn chi ra ring vdi trudng hgp mSi dit

dSo, h$ sd an toSn tPng thi tinh toSn theo phuong phSp kit hgp nhd hon khS

nhiiu so vdi cSe phuong phSp truyin thing.

Summary: Landslide occurs when a soil mass moves on a soil slide

caused the failure along the slip surtace. Landslide damage is well known very

tremendous. Basically soil slope stability is analyzed by one of some conventional

methods such as Bishop, M-P, which based on limit equilibrium theory.

Therefore, conventional methods can not consider some factors as Poisson

ration, deformation modulus. The stability analysis based on the stress field

obtained from FEM analysis ean take into account the factors, which is out of

stability analysis in the conventional methods. The example results showed that

in case of excavated earth slope, overall factor of safety calculated by the method

based on FEM stress field is lower considerably to that of conventional methods.

1. TONG QUAN VE ON DjNH MAI DOC

Mdi dde ty nhidn cQng nhu mdi dde nhdn tgo diu eo thi bj mit dn djnh vd bi trupt Id vdi

nhiiu nguydn nhdn khde nhau nhu: trpng lupng ban thdn; tai trpng edng trinh; hay su thay ddi

eda cdc yiu td dja chit, thdy vdn... Nhin chung sy mit dn djnh ndy Id cdc biin dang cit khi

chdng phdt trien thdnh nhu'ng mdt trupt lidn tyc.

1.1 H$ s6 an todn tdng thi

O i ddnh gid dp 6n djnh cda mdt mdt trupt trong mdi dit ngudi ta sd' dyng ty sd giQ'a kha

ndng chdng cit dpc theo mdt trupt Tf vd lyc cdt trdn mdt trupt T. Ty sd ndy dupc gpi la hd sd an

todn eda mdt trupt dP. Theo thuyit bin Coulomb, hd sd an todn cd the dupe xdc djnh theo

cdng thi>c:

^ _ T, c + otanjip) ..J,

TAP CHf KHOA HOC CONG NGH$ XAY DUNG Sd02 -12/2007 75