NHlN RATHE GlOl # # J
Cac cong trinh ven bien: Bai hoc rut ra tur flia chan va song than
TAKAHIRO SUGANO Vien nghien cdu Cang vd San Bay
Gidi thieu
Ngdy 11/3/2011, trdn ddng dat Idn nhlt tung dugc ghi nhan tai Nhat Ban da ddnh vao bd b i l n khu vuc Tohoku cua Nhat Ban.
Trdn dpng d l t nay dugc Co quan khi tugng thuy van Nhdt Ban gpi Id "trdn ddng dat Tohoku ngodi khoi Thdi Binh Duong nam 2011" Tran ddng ddt Idn 9 dp gay ra nhu'ng dich chuyen manh anh hudng tdi dao Honshu t u vjnh Tokyo d i n cue bac eua dao vd gdy ra mdt loat sdng than quet sgch todn bd eac cdng trinh ven biln trong todn bd khu vuc. Tiep theo la cdc d u chan Idn (Mw>7) phd huy khu vuc vjnh Tohoku ngay khi xay ra eac ung xu khan cap va cac nd luc phge hoi.
Bdo cdo ndy tdm tdt nhung tim kiem cua dpi nghien cuu thudc Vien nghien cuu Cang vd Sdn bay khi kiem tra cdc cdng trinh ven b i l n dpc tren chilu ddi 600km bd b i l n , cdc thi nghiem kilm Chung vd cdc phan tich. Mdt yeu to dgc trung cua djch chuyen dat n l n quan sdt dugc Id ehu ky ddi vd t i n so cao. Vi t h i md muc dp phd huy cdc cdng trinh ven biln dp djch chuyin dat n l n Id khd nhe. Muc dp bao phu rdng Idn ndy giup Idm sang td cdc y l u to h u hai tren todn bd vung anh hudng bdi ddng dat bang cdeh phdn biet cdc cdng trinh ven biln bj hu hai vi rung l i e dat n l n mgnh vd vi cae hieu ung thu edp (nhu hda long, phd huy n l n , lun) sinh ra do nggp Igt chinh vd keo theo do sdng t h i n gay ra.
Hinh1.
Tudng ke dpc van thep d cang Hokkaido b|
hu hong trong tran dpng dat Hokkaido- Nansei-Oki nam 1993
HU hdng cac cong trinh ven bien
Trong nhilu trudng hgp, d i l u kien Idm viee eua cae cdng trinh k i l m tra tai thdi d i l m khao sat cua chung tdi Id do tdc ddng k i t hgp eua ddng ddt vd sdng t h i n gdy ra vd khdng t h i xdc djnh dugc tai hien trudng chudi cdc phd hiJy va anh hudng tuong doi do tai trgng dpng d l t vd sdng t h i n gdy ra. Cdc gia djnh ndy dugc dua ra dua tren k i t lugn ky thuat tcng hgp dugc thuc hien l l n d l u tren cdc cdng trinh ven bien cung vdi cdc phdn tich dang ghi nhan tren toan the gidi v l ddng d i t vd cdc trudng hgp nghien cuu cua cdc trudng hgp tuong t u (gidng nhu d i l u tra "tdi pham"). Nhilu didn giai v l cdc dang phd huy trinh bay trong bao cao ndy Id se dugc t i l p tgc sua doi d l d l phu hgp hon vdi cdc sd lieu tai cdc vj tri khao sdt ehinh. Vide tim kiem va ddnh gid trinh bdy trong bao cdo ban dau dugc thg'c hien d l thuc hien theo cac bdn bac trong cdng dong chuyen mdn v l cang, thuc
d l y cae nd lue nghien cuu ung dung vd hudng tdi trinh dp nang cao vd ky ndng tdt nhlt.
Trong bao cdo ndy, tdc gia xin dugc trinh bay dang pha huy tieu bilu do djch chuyin ddng d l t k i t hgp vdi sdng t h i n gdy ra, trinh bdy quan d i l m v l tdng quan thilt k l trong tuong lai xet den tdc dgng eua ea ddng d l t vd sdng t h i n .
Mdt dac trung tieu b i l u eua dang phd huy do djch ehuyin d i t nen gay ra Id biln dang mat hudng ra bien eua tudng ke vd lun d l t sau tudng ke. Bien dang mat hudng ra bien cQa tudng ke la nhd so vdi dich chuyin d giua cua cua canh ke, thudng theo dang cung trdn thoai nhu trong hinh 1. D i t n l n bj lun ngay sau tudng ke tang ciJng vdi djch ehuyin cua mat hudng ra biln.
Vi t h i md todn bd b i n neo bj hu hdng khdng su dung dugc.
T i l p theo xin xet tdi pha huy cua mot tudng ke cpc van thep g cang Soma trong tran dpng dat Tohoku ngodi khoi Thai Binh
So 9 nam 2012
.CaEEI
MMMM NHiN RATHE d o ' i
Duong ndm 2011 ndu trong anh 2. Hu hdng cua tudng ke do tdc dgng eua djch chuyin d i t nen vd song t h i n keo theo gdy ra id hgp ly. Tuy nhien, trong eae nghien cuu ve cang ehju thien tai, cd nhilu dang phd huy khde do djch chuyin d i t nen gay ra khdng t h i tdeh rieng vdi tdc dgng do sdng t h i n gay ra. T u su khde nhau giiJa phd hOy do dieh ehuyin d i t n l n vd do sdng t h i n gay ra se tim ra dugc nguyen nhan gay pha huy tudng ke. Su khde nhau gida anh 1 vd anh 2 la dp pha huy cua cd hai tudng ke id g i n nhu nhau thi todn bd phd huy xult hidn tren tudng ke treng anh 1. Tudng ke d cang Soma ehi bj phd huy trong gdc va tren 30m tudng, cae phan khde d l u khdng bj anh hudng.
Khdng biet dugc chi t i l t qud trinh phd huy tai thdi diem xay ra. Tac gid du djnh se co gang 1dm rd qud trinh phd huy bang thue nghiem vd phdn tich so.
Y tudng ve triet ly thiet ke mdi xet tdi tac dung cua ca dong dat va sdng than
Nam 2007, Tieu chuin thilt k l cdc cdng trinh cang eua Nhat Ban dd dugc sua doi quan trpng. Yeu to quan trpng nhlt cua tieu chuin thilt k l mdi ndy la trilt ly thilt k l hodn todn dua tren "phuong phdp thilt k l dua tren sg- Idm viec". Tieu chuln mdi cung dugc thilt k l de phu hgp vdi nhung thay doi g i n day trong ITnh vuc nghien cuu ve dia chit vd ddng d i t . Theo tieu chuln thilt k l hien hdnh, nen khao sdt vd danh gia eae hu hdng xet d i n ca tai trpng do djch chuyin dja c h i n vd do sdng t h i n gdy ra trong tran ddng d l t Tohoku ngodi khoi Thdi Binh Duong nam 2011 d l cai t i i n tieu
landward Isunatn Isurarri flow
jXhytfeBiAcfoice
> amount of excsvaboii
>^stalilerttheiepacedsa«w. permeeble pnBSSJI^
REPLACED S A I *
Anh 2.
Tudng ke cpc van thep b cang Soma bj pha huy trong tran ddng dit d phia Dong Nhat Ban nam 2011
Hinhl Cc cau pha hoai gia djnh cua de chan song
chuan thiet ke hien hdnh.
Y tudng "phuong phdp thilt k l dua tren su idm viec" la n l n tang cua tieu chuin thilt k l mdi.
"Mgc tieu cQa cdng trinh" dugc dat len hang d l u trong qud trinh thilt k l . Sau dd "eac yeu c l u lam vide" dugc cg t h i hda trong "ehi dao cua bd trudng" d l dat dugc yeu c l u cua cdng trinh bdng ngdn ngu don gian d l ngudi dan cd t h i hilu dugc mgc tieu eua cdng trinh. T i l p theo, "tieu c h u i n lam viec" dugc dat ra d l dat dugc cdc yeu cau Idm viec cua cdng trinh, trinh bdy bang cdc thuat ngu ky thuat d l cdc ky s u chuyin
tai ehinh xdc cdc tieu chuln nay Cudi cung, su Idm vide cua cdng trinh dugc kilm tra bang met so
"phuong phdp kilm tra"
Tren quan d i l m dja ky thuat, mdt phd hoai cdng trinh theo thdi gian do ddng d i t vd sdng than gay ra dugc tdm tat nhu sau:
a) Gia tdc ung xu Idn, biln dang Idn, vat lieu bi phd hoai nhu hda long nen d i t vd cdc v l t ndt phdt triln nhanh
b) Luc sdng t h i n , tdc dung cua ddng chay nhu luc trdi, day ndi, va xd vat ndi khi xay ra sdng t h i n . Ode biet Id khi sdng than
So 9 nam 2 0 1 2
NHiN RATHE GIOI MMk
hudng v l phia b i l n thi cd t h i xult hien s u m i t 6n djnh cua dp lye nudc lo rong trong d i t n l n giong nhu hieu ung keo chim nhanh ehdng nhu trong hinh 1.
Hien nay, v i n chua xdc djnh rd dugc nguyen nhdn phd hoai va CO c l u phd hoai thuc t l do sdng thin gdy ra. Chung tdi dang t i i n hdnh nghien cuu thuc nghiem va md phdng sd d l lam sang td co c l u phd hoai do tdc dgng k i t hgp eua ddng d i t vd sdng t h i n .
D I ban hdnh mdt y tudng thilt k l mdi cho cdc cdng trinh ven biln vdi "thilt k l b i n " chong lai tac dgng k i t hgp cua ddng d l t
vd sdng t h i n , c i n phdi xdc djnh dugc cae d i l u kien tai trpng, cdc yeu c l u Idm vide, cac tieu chuin Idm viec vd phuong phdp kilm tra.
Yeu c l u xdc dinh dugc su k i t hgp chinh xdc eac dieu kien tdi trpng khi xay ra sdng t h i n Idn, khd chuyin tai dugc cdc yeu c l u lam viec nhu "dam bao hoat ddng" vd "cd kha ndng sua chua"
vdo cdc tieu chuin lam viee vd d trang thai hien nay, khd kilm tra duge viec thiet k l cd dp chinh xdc vd lugng.
Hien nay, chung ta cd t h i
"thilt k l " khi sdng t h i n x u l t hien
thudng xuyen. Ngodi ra, khi sdng t h i n Idn xay ra, chung ta dua ra "y tudng thilt ke". Rut kinh nghiem t u trdn ddng d i t nam 1995, khai niem v l djch ehuyin ddng d i t c i p 1 va d p 2 dugc dua ra va viee dua thilt k l khdng c h i n vdi hai c i p dp djch ehuyin d i t ndn vdo dp dgng keo ddi trong vdi nam.
Tuong ty, eIn vdi nam d l dua y thudng thilt k l mdi vdo hien thuc de xet d i n sy Idm viee k i t hgp eua ddng d i t vd sdng t h i n vdi sy ddng thuan eua nhung ngudi ed chuc trdch nhu cac nhd thilt k l , ede quan chuc xay dyng, cdc nhd quan iy, v.v...
Cac fle song bj pha hoai va cac bien phap phuc hdi va tai thiet cong trinh
Gidi thieu
Trilt ly thiet k l khdng c h i n trudc day cho cdc de sdng d Nhdt Ban von dua tren y tudng he so an todn Idn hon 1, tuong t y nhu thiet k l cdc cdng trinh khac.
Khi thilt ke de sdng can xet d i n hai y l u to quan trpng. Y l u to d l u tien la v l tdi chinh d l tong chi phi cho cdc bd phdn khdng c h i n tren mpt don vj chieu ddi de Id han c h i vi tcng c h i l u ddi Idn cua de Id cdng trinh nhay cam vdi ddng dat. Y l u to thu iiai Id yeu c l u he so an todn khdng c h i n phai nhd hon 1 se cd se xay ra tham hpa ho^c ngap nude ngay lap tuc vi xdc s u i t xuat hien ngau nhien eua mOt trgn ddng d i t mgnh hoac mdt tran Igt Idn Id r i t t h i p . Vi t h i , he so an todn khdng c h i n Idn hon 1 Id khdng bdt budc.
Khuyin nghj kha nang phuc hoi hu hong de sdng^ trong khoang thdi gian ngan, dien hinh
id 14 ngdy. D l dgt dugc muc tieu nay, can phai dp dgng nguyen ly thilt k l khdng c h i n dya tren su Idm vide vdi biln dgng cd t h i cua cdng trinh dudi tdc dung eua mdt tran dpng d l t thilt ke cho trudc la tinh todn dugc, so sanh vdi su biln dang cho phep vd n l u so lieu tinh toan vugt qua gidi han cho phep thi phai k i l m tra hieu qua lam vide cua moi bien phdp khang c h i n . Vdi quan d i l m ndy, bdi bdo ngan ndy gidi thieu ve cac de sdng ehju anh hudng cua trgn ddng d i t Idn d phia Ddng Nhdt Ban nam 2011 vd nhung cdng trinh khang c h i n thanh cdng.
Pha hoai do dgng dat gay ra tren cac de sdng nam 2011
Hinh 1 cho t h l y vj tri eac sdng vd cdc cdng trinh de sdng dugc trinh bdy trong bdi bdo nay.
D l u tien Id de tren sdng Tone tgi Sawara (dnh 1) ehju pha hogi
GS. IKUO TOWHATA Khoa Cdng trinh, Dai hoc Tokyo dien hinh cua mdt cdng trinh de hoac dap c h i n tren n l n d i t bj hda Idng, dinh bi lun vd cdc v l t nut dpc do hieu ung cang thu c i p . Thdng thudng nhu vay bai sdng von Id mdt phan eua ludng sdng vd bj l i p bdi d i t dd nhan tao hoac tu nhien, tgo nen d i l u kien t i n g d i t hda idng nghieng.
Mdt trudng hgp dang chu y Id de sdng trong anh 2 ed biln dang Idn x u l t hien ngay ed tren d i t set vd sau dd d t i n g d l t khdng bj hda Idng. Vi biln dang sinh ra d eae de sdng nhu vay thudng cd dinh bj lun vd hien tugng cang thu c l p Id dgng biln dang t y nhien d i i n hinh do hda long gay ra cho mdt dap c h i n nen hu hdng the hien trong anh 2 dugc cho la do sy hda long bien trong cae bp phdn cua de gay ra. Co c i u eua y tudng mdi nay dugc dua ra theo cdc nghien cuu cua Sasaki vd cdng sy (1994)1) va Kaneko
So 9 nam 2012
