KHQA HQC - C 6 N G N G H § Tap Chl GTVT 12/2012
m
UfNG DUNG MO HINH HOA TRONG DANH GIA NGUY CO TRUOT L 6 DAT CHO CONG T R I N H
GIAO THONG, VI DU QL6 TINH HOA BINH
TS. VU ANH TUAN ThS. NGO DUfC ANH ThS.
N G U Y I NTHj THU THUY
Trung tam Vd tinh qudc^ia - Vidn KH&CN Vidt Nam ThS. NGUYEN DJNH KHQA
Vidn KH&CN GTVT- BQ GTVT
Tom tat: Thdng thudng, md hinh hda vi GiS (hd thdng thdng tin dja ijf') duac sd dung trong dinh gii nguy ea truat Id ddt d quy md iinh thd tuang ddi rdng Idn. Si/phong phii eua cic md hinh dinh gii vi ty id nghien edu din tdi stf phong phii cic nghidn edu lidn quan. Trong nghien cdu niy, chiing tdi t$p trung thd nghidm cic md hinh thdng dung tren Thd gidi vi d Vi$t Nam trong dinh gii nguy ca trutft id ddt vdi ty Id idn, phu hap trong cdng trinh giao thdng. Qua thd nghidm t^i Qudc id 6, dogn di qua tlnh Hda Binh, cic uu nhuac diem cua tdng iogi md hinh duae dinh gii lim ca sd eho cic nghidn edu sau han vd sd dung md hinh hda vi GIS trong dinh gii nguy ca truat id dat eho cdng trinh giao thdng.
Abstract: Normally, modeling and GiS (geo- graphic information system) is applied in land- slides risk assessment at scales which relatively correspondents to large territory. There are several assessment models as well as scales of assess- ment. This leads to richness of researches in land- slides risk assessment. In this study, testing of several landslide risk assessment models which commonly have been used around the World as well as Vietnam is applied In detail scale for accor- dance with the transport works. From the result of case study Highway 6, part of Hoa Binh province, the advantages and disadvantages of each land- slide risk assessment model are evaluated as a basis for further researches on the use of modeling and GiS in assessing the risk of sliding landslides for transport works.
1. Gidi thidu
Nhidu ky thuat phan vdng trgpt Id da dUde phat triln trong vdng vai thap kj' qua (nhu Hansen, 1984;
Varnes, 1984; Soeters, Van Westen, 1996; Aleotti, Chowdhury, 1999). Trong nhOng nam g i n day, mdt sd phUdng phap tidp cdn mdi eho phan tich trupt Id da dupc thgc hi^n nhg eac mgng nd ron nhan tgo (Ereanoglu, 2005), (Ermini va nnk, 2005.), (Lee va nnk, 2003), (Lee va nnk, 2004), (Nefeslloglu va nnk, 2008), (Pradhan va Lee, 2010a), (Pradhan va Lee, 2010c) va (Pradhan vd nnk, 2010a), logic md (Akgun va nnk, 2011), (Ereanoglu va Gokceoglu, 2002), (Er- eanoglu va Gokceoglu, 2004), (Kanungo va nnk, 2008) va (Pradhan, 2010a), cay quydt djnh (Nefesll-
oglu va nnk, 2010), va nd ron md ((Kanungo va nnk, 2006), (Oh va Pradhan, 2011), (Pradhan va nnk, 2010b), (Sezer va nnk, 2011) va (Vahidnia va nnk, 2010). Ndi chung, eac phUdng phap nay tang eudng xu hudng lap bdn dd dinh tinh vd djnh lupng cac khu vue ed nguy cd trupt Id dat, va k i t qud mang tinh khdng gian la hdp ly (Pradhan, 2010b).
Sg phong phu ke trdn cua cae md hinh danh gia nguy ed trupt Id d l t khien eho cae nghien cOu v l ITnh voc nay cung trd nen h i t sdc phong phd, va nhilu khi, tgo nen so khd khan trong vide lOa chpn md hinh nao. Vdi cdng trinh giao thong, ty Id nghien cOu yeu d u Idn (chi tilt) nen vide lOa chpn md hinh cdng thdm khd khan. VI ly do dd, thdng qua viec tien hdnh nghien cUu trdn cdng mot bp dO lieu cda cdng mot khu vOc (Qudc Id 6, dogn qua tinh Hda Binh) vdi n h i l u md hinh khae nhau, Ou nhope diem vd k h i nang ap dung cda cac md hinh dope bode dau danh gia nhIm tgo ed sd eho viec Iga chpn md hinh danh gia nguy cd tropt Id d l t .
Cae md hinh dope danh gia trong nghidn cOu ndy bao gdm: Md hinh t i t djnh (SINMAP; TRIGRS, SHALSTAB); md hinh thdng kd (hdi quy da bidn); md hinh suy nghiem (tinh trpng sd theo phOdng phdp AHP).
2. PhOdng phap mo hinh hoa trong danh gia nguy cd trUpt Id da't
Nhin chung, cac ky thuat phan vdng tropt Id ed thd dope chia thanh cdc phUdng phap true tiep va gian t i l p . Trong sd eac phUdng phap true tiep, phUdng phap dja mgo dOa tren kinh nghiem va kien thOe v l dieu kien dja hinh cda khu vOc nghidn cOu d l trge t i l p xdc djnh mOc dp nhgy e l m . PhOdng phap gian t i l p sd dung cae mo hinh thdng ke hoae md hinh tat djnh d l dg doan cac khu vOc cd kha nang x i y ra trOdt Id doa trdn cdc thdng tin thu dope tO vide nghien edu mdi quan he giOa eac nhdn td dieu kidn trupt Id va sO phan bd cda cdc diem trUpt Id.
c a c phUdng phap chfnh dUpc d l cap trong cac cdng trinh da cdng bd ed thd dupe nhdm lgi thanh cac nhdm chinh sgu day:
(1) Lap b i n do nguy cd dja mgo, phan tich trupt Id dat (da x i y ra) cho khu vgc nghidn cufu;
(2) Phgdng phap suy nghidm (heuristic) hay dga trdn chi sd;
(3) Cdc md hinh dga tren thdng kd;
Ml
KHQA HQC - CQNG NGHE(4) Hoae eac md hinh dga vao ban chat vat ly vd dja ky thudt (md hinh tat djnh);
Hidu mot cdeh ddn gidn, md hinh la nhOng mo ta dupc rut gpn lgi mot thgc t l nao dd de cho thay ban c h i t hogt ddng cda thgc td dd. NghTa Id md hinh dgpc xdy dgng nham phgc vg eho vide nghien edu cdc hien tupng hoae eac van dpng phUe tap. Tong quat hda, md hinh danh gia nguy ed trOdt Id dat cd t h i dope b i l u d i l n qua cdng thUc: NC= f(nt). Trong dd: NC: Nguy ed tropt Id dat; nt Cac nhan td anh hodng; f. ham bleu thj mUc dp anh hodng cda cac nhan td tdi nguy cd trOpt Id d l t .
Nhu vay, ed the thay rang md hinh la mot ham sd b i l u thj vai trd, mdc dd I n h hudng cda cac nhan td I n h hudng tdi nguy ed trupt Id d l t . v a nhU vay, vide xay dgng md hinh, hay md hinh hda, chfnh la qua trinh tim kidm ntva f
Trong vide xac dinh nguy ed trgpt Id d l t , do tinh c h i t qua da dgng eija d i l u klen thgc t l , viec xay dgng cac md hinh md phong de tim ra ly thuyd't v l trupt Id la khdng kha thi. Chinh vi vdy, cac md hinh thudng dUde xdy dgng thdng qua cac cdeh sau day:
- SCf dung sd lieu thdng ke: Dga tren cac d l l m da x i y ra trupt Id d l t , vdi g i i djnh la cac dilm ed d i l u ki$n cang g i n gidng vdi nhOng d i l m da xay ra trupt Id d l t la cae diem cd xac xuat (hay nguy cd) xay ra trupt Id d l t cang Idn.
- Sd dijng phUdng phip chuydn gia: Vlec xay dgng md hinh theo phUdng phap nay phg thude r l t nhilu vdo kinh nghidm eua chuydn gia. Theo dd, cdc nhan td dnh hudng dupe xac djnh thdng qua cac bude phan tich logic, thudng chia thanh hai logi: Nhan td thde day (gay trupt Id) va nhan td kim ham (gilm trupt Id). Vai trd cda eac nhan td nay dupe ehuyen gia quydt djnh thdng qua qud trinh phan tfch va gan trpng sd. Cung da ed mot sd phUdng phap (vi dg AHP) de qua trinh nay didn ra giam thidu sg phg thupc vdo kinh nghidm chuydn gia.
3. Cac md hinh dUpc thd nghiem
Cdc phgpng phap tren dda tdi cac logi md hinh sau thgdng dupc sd dgng trong phdn tich nguy ed trupt Id d l t :
- Md hinh tdt djnh (deterministic): Day la mot dgng md hinh dga trdn phdn tfch bdn chat vat ly cda qua trinh trupt Id d l t va dieu kidn dja ky thuat cua khu vgc nghidn cdu. Md hinh logi ndy thudng dupe cdc chuydn gia dja chat, dja mgo thgc hien, ed ging mieu t l b i n chat vat ly cda eac nhdn td anh hudng tdi nguy cd trupt Id d l t . Vdi md hinh nay, qua trinh trupt Id d l t la qua trinh vat ly, vdi cae Ige tac dpng lam pha vd trgng thai can bang. Md hinh ndy giup danh gia khi ning trgpt Id d l t .
- Md hinh suy nghidm (heuristic): Day la dang mo hinh doa trdn phan tich vd eac nhan td cd the gay I n h hudng tdi trUdt Id d l t . Doa trdn cac diem da x i y ra trUdt Id (coi nhu dap sd ddng da cd eua bai toan), cae chuydn gia ddnh gia vai trd cda cae nhan td I n h hudng thdng qua qua trinh eho trpng sd. Md hinh nay gidp danh gia nguy cd trupt Id d l t .
- Md hinh thdng kd. Ddy la dgng md hinh dope xay dong doa hoan toan vao phan tich thdng kd v l mdt
todn hpc cac d i l m da xay ra trOpt Id ddt. Cd nghTa \i md hinh nay coi cac d i l m da trOpt Id chinh la eac ddp so da cd, to dd xay dgng mot ham toan hpc vdi cac dO lieu da cd d l cd dope mot Idi gidi tOdng ddi gin eac dap sd nay nhat. Md hinh nay giup danh gia xac xui'txky ra trUdt Id, hoae nguy cdtrUdt Id.
Trong nghien edu nay, cac md hinh sau dupc sil dgng: Md hinh thdng kd (Hdi quy da bidn); M6 hinh suy nghiem (xac djnh trpng sd theo phUdng phdp AHP); Md hinh t i t djnh (eac md hinh SINMAP, SHALSTAB, TRIGRS). Bp dO lieu sd dgng trong nghien edu bao gdm cdc logi bdn dd sau day: dp ddc, hudng sudn, lUdng mua, mat dp dOt gay, mat dp thijy van, dUdng thu nude, khoing cdeh den dUdng thu nudc, dp bao hda, hudng dong chdy, pit-filled DEM, bdng dja hinh va eac d l l m trUpt Id.
4. Kdt q u i
SCf dung bd dO lieu nhu nhau trdn cdng mdt khu vuc, kdt qud tinh toan vdi 5 md hinh khae nhau di/ijc the hidn tren hinh dUdi day
Hinh 1: Kdt qui tinh tain theo cic md hinli khic nhau
Cdc k i t qua tinh toan dUpc so sanh vdi cac s6 lieu quan sat trdn thgc dja nham t i l n hdnh kilm chu- ng va thgc hien ddnh gia. Tdng cdng 34 dllm trSn toan t u y l n QL6, dogn qua tinh Hda Binh da dU(?c danh gia. So sanh vdi sd lieu thgc dja, cd t h i thiy r i n g cac md hinh d I u kha chfnh xac, theo do, m6 hinh suy nghidm va md hinh thdng ke cd dd chinh xdc g i n tUdng dUdng nhau.
Bang 1. Dinh gii dd chinh xic
So ( l i ^ chinb m'c iiiyet dSi*
So diem cb inh xic lUttipda**
M6h<nh SNMAP
V' :4
nUGRS 16 28
SHALSTAB 5 22
THONG Kii 7 21
TJie phan tram chinh xic Di^el da TylephSatrim cijnh xic gftiydoi
»
7?
48 85
15 67
21 Dl
SUYNCHItM
12 25
36 76
"Tuyet ddi: Kdt q u i tinh toan va thgc dja hodn todn gidng nhau; "TUdng ddi: K i t q u i tinh toan cao hdn mdt cap v l mdc dd nguy h l l m so vdi thgc dja.
5. Danh gid cac m6 hinh
Nhin trdn sd lieu so sanh k i t qud tinh toan va thac
KHQA HQC - CONG NGHE Tap chl GTVT 12/2012
If
dja, cd thd t h i y md hinh TRIGRS cho k i t qud tUdng ddi sat thgc, cd mot ddi chd hdi cd sg khuech dgi mdc dd nguy hiem. Md hinh SHALSTAB cd xu hudng khudeh dgi mgnh hdn. Dieu ndy cd t h i ly giai la do qua trinh phan Idp mOc dd nguy hiem cda md hinh nay choa dope chfnh xac, can cd nhilng khao sat va phOdng phap phan logi lgi de md hinh cd k i t qua tdt hdn.
V l mat khdng gian, khi so sanh cae ban dd nguy cd tropt Id dope tinh toan theo eac md hinh tat djnh khae nhau, cd the nhan thay r i n g :
Md hinh TRIGRS tOdng ddi nhgy vdi mOc dd phan c i t sau cda dja hinh. Md hinh nay thodng dua ra mOc dd c i n h bdo (nguy hilm) cao vdi nhOng khu vgc ed dd phan e l t sdu Idn.
- Md fiinh SINMAP ed dp nhgy vda phdl, thd hidn khd rd mUe dd ednh bao khae nhau trong eac khu vgc cd nguy ed trgpt Id dat.
- Md hinh SHALSTAB eho eac mOc dp canh bao thIp hPn so vdi hai md hinh edn lgi trong h l u h i t eac trodng hpp. Tuy vay, md hinh nay mang tdi bde tranh cd phln "hien thOe" hdn khi cac d i l m cd nguy cd trupt Id ed didn tich vda p h l i , khdng qua Idn nhu md hinh TRIGRS va md hinh SINMAP.
D l ddng nhdn thay vdi k i t qud cda mo hinh thdng kd, ydu td lupng mua dupc n h i n mgnh khi cdc khu vgc cd nguy cd trgpt Id cao gan lidn vdi nhOng khu vgc ed Iddng mua Idn. Vdi nhiJng khu vgc nhg Hda Binh, khi dia hinh tgdng ddi da dgng va ed dp phan elt sau kha Idn, thgdng thi d i l u nay khdng x i y ra.
Tuy nhidn, k i t q u i trdn t h i hidn ro mot d i l u Id lupng mua cd vai trd r l t quan trpng, ndu khdng mudn ndi Id quydt djnh, ddn nguy ed trUdt Id dat d Hda Binh.
Kdt qud tinh todn vdi md hinh suy nghidm tUdng ddi g i n gidng vdi md hinh t i t djnh hdn, khi vai trd cua ydu td lupng mua khdng dUde ndi bat nhu vdi md hinh thdng kd. So sanh vdi cdc quan sat trdn thuc dja, phUdng an cdn b i n g cd dp chfnh xac cao hdn, trong khi phUdng an chap nhdn rdi ro cd xu hudng khudeh dgi nguy cd trupt Id.
6. Ket lugn
Kdt q u i eug nghidn cOu la cdc b i n dd nguy cd trupt Id dd't eho khu vgc nghien cOu tinh todn theo cdc md hinh khae nhau d tjr Id 1:50.000, thd hien it nhlt cac d p dd nguy cd trgpt Id d l t khae nhau. Cac k i t qua trdn cung dUpc phdn tich, ddnh gia va so sanh vdi sd lidu thgc dja va didu tra.
Do mdi chi thgc hi§n tren mot khu vgc nghidn cOu la tinh Hda Binh vd edn n h i l u hgn c h l v l sd lieu thdng kd tropt Id, nen cdc kdt qua cd dope trong danh gia trOdt Id cdng trinh giao thdng chi la djnh hodng bode d I u . Nhdm nghien edu kidn nghj eIn md rdng nghidn cOu tOdng tg, ddc bidt la cdeh tidp can da md hinh cho cae khg vgc khae d Viet Nam, cd d i l u ki$n g i n gidng hodc hoan toan khae biet vdi khu vgc da nghldn cdu.
Nhdm nghien cOu cung nhdn thdy r i n g c I n p h l i tach bidt nghidn cdu nguy cd tropt Id d l t eho cdng trinh giao thdng vdi eac nghien cOu trOpt Id d l t khae, mang tinh c h i t lanh thd va phgc vg quy hogch do didu kidn d$c thd cua dOdng giao thdng la dope sd
dgng thodng xuydn. Rd rang didu nay, dii ehua dupe nghien cOu, cd i n h hodng tdi dp b i n cong trinh, nhat la eac trOdt Id xay ra d taluy am, ndi c h i c c h i n chju anh hodng cda vide sd dgng mat dgdng vdi eac xe tai trpng Idn •
Tai lieu tham k h I o
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