OjAKY THUAT-TRAc OIA
AP DUNG P H U a N G PHAP GIAO THOA RADAR D S XAC DINH HlEN TU'QNG LUN DAT TRONG VUNG DO TH! TRUNG TAM THANH P H 6 HA NQI
T S . O A N G V U K H A C T r u d n g d a i h g c S u p h a m Ha Npi
T h S . N G U V e N C O N G K I E N . T h S . D 6 N G MINH T A M Vien K H C N X a y d g n g
Tdm tat: Vdi phwang phdp phdn tich giao thoa da thdi gian, chung toi khao sat hign twyng lun dat tgi vOng do thi trung tam cua thanh pho Ha Ngi bing anh v^ tinh ALOS PALSAR thu chup trong giai doan 2007- 2011. Ban dd toe dd liin trung binh cho thiy khu vyc phia bd bic song Hong khd on dinh, trai lai mgt so khu vyc d bd phia nam dang bj lun voi van toe eye dai dgt 68 mm/nam. Mat dit bi biin iigng trong ba khu vyc chinh: qudn Hodng Mai, qudn Ha Dong - Thanh Xudn, huygn Tir Liem - Hoai BCrc, tgi nhimg nai ma vigc xay dyng dang phat trien rim rg va vigc hiit nwac ngim dang diin ra manh me trong thap nien vira qua.
Ngoai ra cdn phai ki din 1 so khu vyc lOn c6 dien tich nho han trong cdc qugn ngi thanh. Kit qua thu dwgc tir phwang phap giao thoa radar twang irng vdi gia trj do dgc bing phwcmg phap thOy chuin trong giai dogn 2007-2008. Diiu ndy chwng minh khd ndng dp dyng phwong phap giao thoa vdo quan trie lun dit tren dign rgng eua thdnh pho Hd Ngi ven do tin egy cao vd gid thdnh hgp ly.
T u khda; lOn dit, do thi hoa, giao thoa radar, vgt tan xa 6n djnh, nwac ngam.
Hign tugng IGn d i t do khai thac tai nguyen thien nhien dudi long d i t ngay cang pho b i l n trong nhung thgp nidn vda qua do nhu c l u tidu thy tai nguyen ngdy eang tang cua xa hpi loai ngudi [16]. LGn mat dat dang d u g c dge bigt quan tam khi nd xay ra tai.
nhilu thdnh pho, nai ma qua trinh dd thj hda mgnh me keo theo s g gia tang nhu eau tieu thy nude v d i lugng n u d c ngam ldn d u g c hut len t u Idng dat. Van d l ndy da duge ghi nhgn tgi cac thdnh pho Idn nhu- Mexieo-Ctty, Bangkok, Thugng Hai, Venice, vd Las Vegas. Tdc dpng cdn ddng quan tdm han khi eac dd thj ndm tren dong bdng boi tich d u g c lap day bdi cac thanh tgo tram tieh b d rdi, d l nen ep. T u nhung nam 1960, eae nghidn c d u v l IGn d i t da d u g c thgc hign vdi n h i l u phuang phap khao sat [28] de cd nhung h i l u b i l t tot han ve e a che hinh thdnh [7] vd v l hgu
qua tac ddng'len mdi t n j d n g [12]. Cae ky thudt do dac b i l n dgng be mat mdt cdch dinh lugng thay doi t d phep do mgt dat n h u phuang phap thGy c h u i n [3] va phuang phdp do gian k l [28] tdi ky thugt khdng gian nhu phuang phap do GPS ttnh [15], phuang phap giao thoa radar InSAR [19], hay phuang phap LiDAR hang khdng [9]
- Thu dd Ha Npi Id mpt v i du ^ I n hinh v l thanh ph6 ed toe dg dd thj hda nhanh trong cac nude dang phdt t r i l n , nai ma n u d c ngam la nguon tai. nguydn chi'nh eho nhu eau n u d c sgch [17]. T u sau Doi Mdi nam 1986, s g nang dpng trong phat t r i l n kinh t l cGng cdc chinh sdch quan ly mdi da Idm cho thanh pho Ha Npi, dac bigt la edc qugn ngi thdnh trd nen hap d i n han doi vdi ngudi nhap c u t u nhieu tinh ldn egn. Hign tgi, thanh pho nay duge chia ra thdnh 10 qugn npi thdnh, 19 huygn ngogi thdnh sau b i n lan dieu ehinh dja gidi hdnh chinh. Dieu nay cho phep ehuyln doi dat ndng nghigp ngogi d thanh dat dd thj vdi vigc thanh Igp mpt so qugn mdi nhu Tay Ho nam 1995, Thanh Xuan va Cdu G i l y nam 1996, Long Bien vd Hoang Mai nam 2003 va Ha Ddng ndm 2008 (hlnh 1). Do do, dan so toan thanh pho tang t d 2.431x10^ tdi 3.184x10^ ngudi t u nam 1995 d i n nam 2006, trong khi ddn so cua cac quan npi thdnh tang g I p ddi t u 1.082x10^ len 2.050x10^ trong cGng thdi ky. S g gia tang dan so dgt d i n 6.472x10^ vao nam 2009 vdi mat do la 1979 ngudi/km^ va xap xi 35000 ngudi/km^ tgi mdt so qudn trung tdm nhu Dong Da hay Hodn K i l m [11].
Vdi viee chuyen doi d i t ndng nghigp sang mye dich dd thi, n h i l u qugn mdi d u g c t h i l t lgp xung quanh khu ndi dd Ijch s u de dap dng nhu cau v l nhd d . Dieu nay dan d i n s u tgp trung ddn c u va khai thac nude ngdm mgnh me t u mdt so bdi g i l n g hut nudc ngam d khu v g c cae qudn mdi thdnh lap. Dieu nay t h i hign qua s g hlnh thanh cGa ba nhd may nude mdi duge xdy dgng trong glal dogn 2002-2005, v d i cong s u i t cua moi nhd may khoang 30000 m^/ngay dem [29].
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Hien t d g n g hg thdp mue n u d c n g i m [19] cGng vdi viec phat t r i l n nha cua tren nen dat yeu da d i n d i n IGn d i t eye bd vd gay ra n h i l u h u hdng eho n i n mdng cdng trinh hg tang, nhd d cua c u dan va ke ca mpt sd tda nhd eao t i n g cu. Trong boi eanh qud trinh do thj hda d i l n ra nhanh chdng sau khi dieu chinh dja gidi hanh chinh cua thanh pho Ha Npi nam 2008, s u hieu b i l t tot han v l b i l n dgng mat d i t trong vung dd thj trung tdm - duge xac dinh bdi 'Do an Quy hogch chung Xay dyng Thii do Hd Ngi din nam 2030 va Tim nhin din nim 2050" td ra e l p bach vi day se la khu vgc tgp trung phdt t r i l n n h i l u cdng trinh xay dgng quan trpng trong tuang lai. Muc tieu Id mpt mat nham triln khai quy hoach chi t i l t mpt each hgp ly va mgt khde Id de k h u y i n khich cdc gldi phap ky thugt xdy dgng edng trinh an toan d nhung nai h\ IGn ddt de dpa.
Nhung nghien edu trudc day dga tren phuang phdp do dge mgt d i t [8], [23], [24] hay md hinh hda nhung dgc tfnh ky thudt cua dat [33] da chi ra mpt sd
nai thudc cac quan npi thdnh b| tde dpng cGa bien dgng be mgt trong vdi thgp men v d a qua. ChIng hgn nhu, khao sat mat d i t cho thay nd bj IGn manh han d khu v g c ndi thdnh han Id khu v g c ngogi vl, dgc, bigt gan cac gieng hGt n u d e n g i m . Mdc dp IGn trung binh thay d l l t d 1.4 mm den 41 mm/nam trong giai dogn 1994-2005 [23]. Tuy nhien, cde phuang phap do dgc mat dat nay khdng thich h g p de theo doi b i l n dgng tren dign rpng nhu IGn d i t vi chung ehi cung d p thdng tin tgl mpt vdi cfilm khdo sdt dan le. Trdi Igi, cdc tinh todn dua tren phuang phdp giao thoa radar - InSAR se eung cap thdng tin v l hign trgng lun dat tren khu vgc rpng Idn vdi dp chinh xdc b i l n doi t u vdi cm d i n vdi mm tGy thupc vdo so ligu s u dyng. Vdi phuang phap ndy, mpt so nghien cuu da tgp trung vao b i l n dang mat dat tgi trung tdm npi thanh [5], [25], [27], [30], [32], [34]. V d i vigc s d dyng each t i l p cgn InSAR truyen thpng, cac nghien cdu nay da ehi ra sg djch c h u y i n theo phuang t h i n g ddng vdi gia trj 20 mm trong glal doan 1996-1998 tgl day [5].
Hinh 1. San do viing do thj Hi Ngi, vdi vj tri cua cac quin ngi thanh vi huyin ngoai thinh [21], Khung vuong twang img vdi khu vyc nghien cuv bing phwang phap InSAR trong hinh 2
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Tuy nhien, cac tdc gia nay khdng thu d u g c toe dp IGn ehinh xac cGa ea vGng do thj trung tam. Han nua each t i l p cgn eua hp ehju mdt so han c h i ca ban cua ky thugt giao thoa. T h u nhdt, so lugng anh ed han cGa anh radar kenh C (chG y l u Id ERS va Envisat eua ca quan hdng khdng vu try chau A u - ESA)[25] vd s u khdng phG hgp khi to hgp gida edc anh radar do dudng ea s d thdi gian va khdng gian phan each nhau kem hgp ly. Han nua, thdi t i l t nhiet ddi sinh ra cac nhieu khi quyen dang k l trong d u ligu dnh radar [31], dgc bigt d tang d l l luu cho ede anh thu tren kenh C (bude sdng 5.6 cm) [36]. Cudi eung, hgn e h l nua ed t h i lien quan tdi s g m i t t u a n g quan gay ra do nhung b i l n doi ve dge tinh tan xg cGa mat dat, chG y l u Id thgc vat trong khu vgc nghien cuu [35]. D l v u g t qua cac khd khan nay, chGng tdi x d ly 22 dnh thu tren kenh L eua ve tinh ALOS PALSAR (bude sdng 23.62.
cm) bdng phuang phap giao thoa trong giai doan 2/2007-2/2011 vdi muc tieu dgt ra nhu sau: 1/ Ve ban do phdn bo khong gian cua hi#n tugng lun dat trong giai doan 2007-2011, 2/ Xac dinh van toe IGn trung binh theo ehilu t h i n g ddng cho todn b | vGng do thi tmng tam va dac bigt Id nhung nai mdi dugc do thj hda (hinh 1),
2. P h u a n g phap luan va s o lieu s u d u n g 2.1 Phwang phap giao thoa radar
Vige su dyng ky thugt giao thoa radar (InSAR) d l do ve be mgt Trai D i t , g i m ca vigc thdnh lap b l mat dja hinh va xdc dinh b i l n dgng mgt dat, da duge minh Chung mpt c i c h thdnh cdng t d han hai thgp ky qua [4]. Phuang phdp giao thoa t r u y i n thong eho phep tao ra eac dnh giao thoa t u a n g dng vdi s g Igch pha khi chyp anh lap Igi nhieu lan. S g Idch pha cua cac pixel dan le nay tuang ung vdi mpt so thdnh p h l n : 0 = 5:(A<Port, + A(p,opo + Acpaim + A ( P N + Acpdef) ( 1 )
6" ddy, Atpofb, Atptopo, A(paim, vd Atpdai la s u Igeh pha l i n lugt gay ra do vj tri cua quy dgo. dja hinh, tre khi quyen vd b i l n dgng be mgt. Thanh p h l n nhieu Acpw lien quan tdi mdc dp bien doi cua tan xg, nhieu nhiet va sal so trong x d 1;^ so ligu. De thu duge thdnh phdn b i l n dgng vdi dp chinh xde cao, vige u d c tinh tot cac thanh p h l n khae Id c l n t h i l t , dga tren so lieu chfnh xac ve cdc tham so quy dgo va dja hinh. Thanh phan b i l n dgng cd t h i d u g c bleu dien theo edng thdc:
A(Pde, = 4TT(AR/A) (2).
Vdi AR la s g b i l n d l l ve khoang cdch giua vg tinh vd mgt dat dpc theo hudng quan sat cua ve tinh va A Id b u d c sdng eua hg thong radar.
Tap chi KHCN Xay dyng - so 2/2015
Do rdt nhgy cam doi vdi djch chuyin thang ddng, viec theo ddi hign tugng IGn do eon ngudi gdy ra bang phuang phap giao thoa radar da trd thdnh mdt trong nhung ung dung chi'nh [10], dac bigt trong khu vgc dd thj nai ma so lugng pixel I n djnh theo thdi gian kha nhieu [6]. Phuang phap InSAR cung da dugc s d dung trong nghien cuu hign t u g n g IGn trong khu vgc do thj vd cde tac gia da cho t h i y b l mat ^ a hinh thdnh pho Hd Chi Minh bj IGn dang bao ddng vd ky thudt giao thoa vi phan la mpt giai phap khd thi nhit trong viec phat hign eae b i l n dgng be mat dja hinh ttieo khdng gian va thdi gian [18]. Tuy nhien, s g m i t tuang quan gay ra hoae do s g thay doi cua hudng quan sat vg tinh doi vdi hai anh (cac gdc nhin khac nhau), hay s g thay doi v l vj tri cGa vat tdn xa, hay sg' thay doi v l hinh hgc ben trong d ea sd. Neu s g mat tuang quan Idn, anh giao thoa se khdng thich hgp eho viec phan tich b i l n dang. Trong tnjdng hgp s g b i l n dgng xay ra manh, thanh p h l n Atpaef ehilm u u the thi nd eho phep xac djnh dugc djch c h u y i n giua hai l i n thu dnh [1]. Tuy nhien, trong tnrdng hgp vdi djeh ehuyen chdm, viec xac dinh thanh p h l n b i l n dgng ed the bj gidi hgn bdi s g noi trpi eua eac thdnh phan khdng b i l n dgng trong phuang trinh (1). Bang each gdp nhilu dnh giao thoa cGa cung mpt khu vgc lgi vdi nhau, ty so tin hieu/nhieu duge tang len, eho phep xac djnh vgn toe djch ehuyen tmng binh cGa mat dat trong giai dogn bao tmm bdi cae anh giao thoa [26].
De v u g t qua s g mat tuang quan ve thdi gian do s g thay doi v l dgc tinh tdn xg, giam tac dpng eua khi q u y l n vd do cac djch c h u y i n tgm thdi; ky thudt giao thoa da thdi gian mdi d u g c phdt t r i l n . Ky thugt nay dga tren vigc thu nhgn n h i l u anh radar ong m d tong hgp va bao gom cdch t i l p can Persistent ScattereiB (PS) va Small Baseline (SB). Nhin chung, hai each tiep cgn nay rat toi u u d l x d ly nhung vdt tan xg tren mgt d i t . Phuang phap PS nham x u ly eae d ca s d noi trdi bdi mpt vgt tdn xg dan le, trong khi phuang phap SB hudng tdi x u ly cdc d c a s d khong cd vgt tan xa n i l trpi. Trong nghien edu nay, chGng tdi s u dyng phuang phdp giao thoa da thdi gian StaMPS/MTI duge phdt triln bdi Hooper. Phuang phdp nay to hgp ca hai cdch tiep cdn PS vd SB d l tach ra d l u higu bien dgng tgi eac d i l m dnh vd Idm tang ty s i tin hieu/nhieu. Vigc Iga chpn d i l m anh PS d u g c thgc hien dau tidn bdng each s u dyng each t i l p cgn PS d u g e phat t r i l n bdi [14], va sau do mpt logt anh giao thoa t h u hai d u g e x u ly bang each tilp egn SB d l xac djnh cac vgt tan xg dong deu (DS) ma doi vdi ehung thi gia trj pha khdng bj mat tuang quan dang k l trong mpt thdi gian ngan. Vige s u dyng phuang phap giao 6 3
OIA KY THUAT - TRAC DIA
thoa da thai gian, dau higu b i l n dgng d u g c tach ra t d ea cac d i l m anh PS va DS md d ddy chGng tdi gpi Id cdc d i l m anh d u g c chpn (SP), cho phep Idm tang so lugng mdu quan t r i e va lam qud trinh m d pha d i l n ra t i t han. D l u tidn qua trinh m d pha 3-D s u dung phuang phap thong ke gia [13], vd vigc udc lugng sai so eua mo hinh so dp eao bang moi tuang quan vdi eac gia tri cua dudng ca s d vuong gdc cua tung anh giao thoa d l m d pha lan t h d hai ed tfnh den eac sda doi nay. Cho tdi thdi diem hign nay, mpt sd ung dyng cGa phuang phdp nay da tap tnjng nghien c d u lun d i t trong dd thi nhu nghien cuu cua [2].
2.2 So lieu
ChGng tdi s d dyng tong so 22 anh radar d u g c thu chyp tren kenh L (bude sdng 23.6 cm) trong thdi gian t u thdng 2/2007 d i n thang 2/2011 bdi dau thu PALSAR dat tren vg tinh ALOS cGa Nhdt Ban. Cae eanh chyp thupc tuyen di len eua vg tinh d ddng 475 va cpt 400 (hinh 1). D l giam t h i l u s g mat tuang quan v l thdi gian vd khdng gian, anh tham ehilu dwq/c chpn tuang dng vdi anh tham ehilu chyp ngdy 25 thang 6 nam 2009 cGng vige s d dyng ngudng 2000 m dng vdi dudng ca s d khdng gian vd 4 nam ung vdi dudng ca s d thdi gian. 20 aph giao thoa do d u g c tfnh todn so vdi dnh tham c h i l u trong phuang phdp PS vd 46 anh giao thoa do d u g c tinh theo phuang phap SB.
Chung tdi gidi hgn khu v g c nghien edu trong dign tfeh
40x40 km xung quanh vGng dd thj tmng tam (hlnh 1).
D l logi bd thdnh phan dja hinh trong dnh giao thoa, ChGng tdi dung md hinh so dp cao todn e l u SRTM V.4 vdi dp phan gidi 3". Mgt khde, thanh p h l n quy dao d u g e logi bd bang each s u dyng so ligu quy dgo vdi dp ehinh xac <1m do JAXA cung e l p trong d l u dan cGa tdp tin di eGng vdi anh radar.
3. Ket qua
3.1 Phan bo kfiong gian va v$n toe cua hign (upng lun Sir dyng phuang phdp phdn tich chuoi so lieu da thdi gian mgt so lugng ldn cac vat tdn xa co djnh (540000 d i l m SP) da dwac chpn Iga trong kbu vgc nghien cdu (hlnh 2). Phan ldn eae vgt tan xg nay t u a n g dng vdi nha d , nha cao tang vd cdng trinh co s d hg tang, nam trong khu ddn c u ddng dGc cua cac qudn ndi thdnh va eac lang xdm d cdc huygn ngogi thanh. Nhung vj-tri khdng cd vdt tan xg I n djnh tuang dng vdi mgt nude hay cac rudng dong ndng nghigp xung quanh khu vge dd thj. De dam bdo hau h i t cac b i l n dgng do d u g c t u a n g dng vdi s g djeh ehuyen cGa mgt ddt do lun theo phuang t h i n g ddng, chGng tdi chuyen doi vgn toe IGn thu d u g e theo hudng ngam cGa ve tinh thdnh vgn toe IGn theo phuang thang dung vdi gdc tdi (6) tgl tung diem anh (6 trung blnli
=38° d l l vdi anh ALOS) theo [22].
6 4
Hinh 2. Vin tic lun trung binh theo phwang thing ddng tgi vOng do thi Hi N& (vj tri trong hinh 1) thu doge tir xi> (i> InSAR c/jo giai dogn tir 02/2007 den 02/2011. Khung vuong H vj tri cua hinh 3c, 3b vi 3c
T9P chi KHCN Xay dyng - s6 2/2015
UIA KY TKUAT - TRAC DIA
ChGng tdi quan sat thay s g khdng dong n h i t ve van toe IGn t h i n g ddng trong vung do thj eua thdnh p h i Ha Ngi, vdi vgn too IGn b i l n ddi t u 0 d i n 68 mm/nam trong khoang thdi gian b i n nam nghien c d u (hinh 2). D l u tien, chGng toi nhan t h i y s g b i l n dang bj gidi hgn chu y l u trong vung dd thj. Vgn t i e IGn tmng binh chi ra s g khac biet rd rdng giua p h l n phia bac vd phan phia nam eua sdng Hong. Cf b d phia bdc sdng Hong, mgt d i t cd ve nhu la r i t on djnh, vdi mpt vdi diem lun nhd ed the nhan t h i y d phia ddng huyen Ddng Anh va khu vuc giua sdng Hong va sdng
Duong, n h u tgi khu v g c trung tdm qudn Long Bien hay phan phfa tdy nam huygn Gia Ldm (hlnh 2). floi vdi cdc d i l m eye bp nay, kfch thudc theo ehieu ngang cGa ChGng khong qua 1-2 km^ moi d i l m , vgn toe IGn tmng binh theo p h u a n g t h i n g dung toi da la 15 mm/nam. 0 b d phia nam sdng Hong, vung phia giap sdng, t u a n g dng vdi cac qugn Tdy Ho, Ba Dinh, C l u G i l y va huygn T d Liem ed t h i phan bigt r i t rd vdi eae b i l n dang nhd, ngogi t r u khu v g c dpc sdng Hong, nai ma lun d i t xay ra vdi toe dp ehgm, nhd h a n 10 mm/nam.
Ktwingcjaitu)
(a) . , (bi (c) Hinh 3. San do phdng to vi lit cat cOa toe dg lOn theo phwcmg thing dOng tgi (a) khu vyc lOn Hoang Mai (b) khu vyc
lOn Hi Ddng - Thanh Xuin (Khung vuong trinh bay khu vyc theo doi IHn bing phuang phap do m$t dat tgi khu do thi mdi Vin Quan), va (c) khu vyc lun Hodi Dire - Tir Liem. Vj tri khung hlnh vi thang gii tri, tham khio hinh 2 Cf phfa nam sdng H i n g , lun d i t xay ra trong 3
khu vgc chinh v l phia nam va phia tay cGa cde qugn trung tdm (hinh 2). D l u tien, khu v g e ldn nhat t u a n g dng vdi quan Hodng Mai d phia nam eua trung tam thanh pho. B i l n dgng t u a n g dng v d i van toe IGn trung binh Idn han 30 mm/nam va bao trum dien tich 5x5 km, vd duge bao quanh d phia bac bdi nhung bien thien vgn toe lun r i t dpt ngpt (hinh 2 va Hinh 3a). Vdn toe lun trung binh toi da dat 68 mm/nam, chi each khu v g e on djnh 1 km. Chung toi ghi nhgn hai vung b i l n dgng rdng vdi kieh t h u d c 2x2 km trong khu vuc IGn chfnh va mpt so diem IGn v d i kieh t h u d c khdng qua 0.5x0.5 km va toe dd IGn dat 50 mm/nam d phfa ddng cGa khu vge lun t h d n h i t nay. Khu v g c IGn t h d hai nam tgi qugn Ha Ddng - Thanh Xudn d phia tdy nam cGa trung tam thdnh pho (hinh 2 vd 3b). Kich t h u d c ngang cua khu v g c lun ndy r i t ldn,
Tgp chi KHCN Xay dyng - so 2/2015
tdi 7 X 4 km nhung it vj tri trong khu v g c ndy t h i hign toe dp IGn t h i n g d d n g v u g t qua 45 mm/nam. Chung toi chi nhgn ra mpt vj trf nhd vdi toe dp lun 60 mm/nam d phia nam. C/ phfa tay cua vung do thj, khu v g c l u n c h i n h t h d ba cd ve hign ra mpt each m d nhgt do s g phdn tan cua cac vdt tan xg d huyen ngogi thanh T d Liem - Hoai Due, nai ma nhdng cdnh ddng ndng nghigp van edn c h i l m u u the (hlnh 2 vd 3e). Cdc diem IGn vgch ra mOt khu v g e 8 x 3 km^ kdo ddi theo h u d n g nam bac md d dd van toe t h i n g ddng thay doi t d 30 den 60 mm/nam. Trong n h i l u p h l n khae cGa vGng do thi, mpt so d i l m lun v d i kfeh t h u d e nhd han 1 km^ phdn bo lgi cac qugn npi thanh nhu Bong Da, Thanh Xuan, hay Hai Ba Trung vdi vgn t i e theo chieu t h i n g ddng thay doi t u 10 d i n 25 mm/nam, nghTa Id nhd han n h i l u so vdi ba khu vgc liin chinh dd md ta.
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3.2 Kiem chwng kit qua
De kiem ehupg ket qua x u ly InSAR eua minh, Chung tdi so sdnh toe dp IGn theo phuang t h i n g dung cho mpt khu vgc eu t h i , nai cd s i n s6 lieu do dac bang phuang phap thuy e h u i n . T u ngdy 25/6/2007 d i n ngay 26/9/2008, Tong Cdng ty Phat trien Nha d va Dd thj Hd Npi tien hanh m u d i sau dgt do mat d i t tai mpt so khdl nha trong khu do thj mdi Van Qudn
n i m d khu vgc IGn t h u hai Hd Dong - Thanh Xuan (vj tri tren hinh 3b). ChGng tdi xem xet mot each ey the han so ligu do mgt dat cGa cac khoi nhd TT18A va TT18B do s g ton tai cGa cdc d i l m tdn xg co djnh tren cdc khoi nha ndy (hinh 4a). Van toe lOn tmng binh suy ra t u so ligu do mgt dat t u a n g dng v d i van toe trung binh 35 mm/ndm ddi vdi k h i i nha TT18A va 27.8 mm/nam doi vdi khoi nha TT18B (hlnh 4b).
f ^0 -g -50
^ ^ ' ^ ^ i t -
-TTiaA
• TT18B
.,,. (ngiy sau 2S/6/Z0O7)
"i•^'Z »~-~».,^, y = 0 OBU' - 3 2« + 2.7
" " ' " • • • - Z ^ — • " - - - , y = 0 0 6 x ' - 3 9 x - 1 6 ' " " *---^.
R> = 0.99
(a) (b)
! 1472 [ng&y sau 2/2/2007)
^ ' 1 1
' ^ " • ' i '
•
. InSAR • 1 — Eniimg hoi quy (Ihiiy chu^n)
Hinh 4. (a) Khu vyc dwgc theo doi tun bing phwcmg phap do mat dat tgi khu do thj mdi Van Quin. Vj tri ciia khu vyc do mit dit, tham khao hinh 3b, va cac diim inh trong khu vyc (thang miu), tham khio hinh 2. (b) Bieu do do lun tich luy cua khoi nha TT18A. Nguon: [8]. (c) Biiu do cua mgt vgt tin xg co djnh nim tren khoi nha TT18B vi gii tq do lun cua no tying phwang phap do tfiuy chuin. Diem thw 3 cua phan tich InSAR theo chudi thdi gian
nim dgc theo dudng hdi quy cOa so ligu do bing phwang phip thuy chuin D i l u nay thuyet phye rang cde gid tri trung binh dd
phG hgp vdi k i t qua x u ly InSAR eua chGng toi vdi gia trj 38.2 mm/nam. va 25,6 mm/nam ddi vdi cac diem tan xg c l djnh ndm tren cae tda nha tuang ung. Tuy nhidn, chGng tdi t h i y rang cdc gid trj nay nhd han van toe trung binh 90 mm trong thdi gian 17 thdng (tu ngdy 2/2/2007 d i n ngay 22/6/2008) t u a n g dng vdi 63.5 mm/nam eho toan bp vGng nghien cuu da d u g e [34] xac djnh. Nhu da de cgp d tren, nghien cdu eua Vdge chi x d iy hai anh bang phuang phdp DInSAR, vdi tat ca cac b i t dmh ed lien quan do s g khdng dong
nhat ve khi quyen, s g m i t t u a n g quan do thdi gian,...
ChGng tdi nhgn t h i y s g t u a n g dong Idn giua so ligu InSAR va so ligu do mgt d i t trong giai doan 6/2007 d i n 9/2008, d i l u nay mang tinh q u y l t ^ n h doi vdi viec danh gid k i t qua thu d u g c t u phuang phap giao thoa radar InSAR (hinh 4e). Trong eung giai dogn ca hai tgp hgp so ligu khdng tuan theo ham so tuyln tinh, phG hgp v d i van toe khdng doi, nhung vach ra mpt ham so da thdc bdc hai. Dieu nay eho t h i y sg suy giam chgm cua vgn toe lun theo phuang thing ddng theo thai gian, nd bieu Ig dpng thai cua Idp d i t T9P chi KHCN Xay dyng - so 2/2015
0!A KY THUAT - T R A C DIA
ehiu s g giam dp Igc lo rdng do hGt nudc ngam. Do dd, t r d cdc n h i l u Idn chda trong so lieu ddi vdi glal doan sau 9/2008, tin higu IGn la ro rdng khdng on dinh nhung bao gom nhung dich chuyen tgm thdi.
4. K i t luan
Trong nhung nam qua, qua trinh do thj hda thue day su m d rdng dd thj vd mgng ludi ea s d hg tdng vdi nhilu d u an xdy dgng xung quanh vGng dd thj Ha Npi. Cdc phuang phap phu hgp d l theo ddi tai b i l n dja c h i t trong vung do thj mdi la h i t sdc c l n t h i l t ddi vdi eae nhd qudn ly de theo ddi hien t u g n g IGn ddt vd hgn e h l cac hgu qua do nd gay ra. S d dgng ky thudt giao thoa radar, chGng tdi khao sat b i l n dgng mgt dat lien quan tdi lun. Phuang phdp nay td ra eanh tranh vdi cdc ky thugt do mgt dat truyen thong lien quan d i n thdi gian va gia thdnh, vi thugt toan ngay cang dugc cai thign va so ligu vd tinh radar ngay eang phong phG. Caeh tiep can phdn tich chuoi so ligu da thdi gian eung e l p mpt dp phu khong gian hoan chinh ve khu vgc nghien cuu va vigc s u dung cac anh ve tinh ALOS thu chyp tren kenh L eho phep chGng tdi vugt qua v i n de m i t tuang quan trong vung nhigt ddi nhu thanh pho Ha Npi. Do dd, lan dau tien, ban do vgn toe syt IGn trung binh eua vGng do thj thanh pho Ha Npi dugc xay dgng. Ban dd ndy ehi ra toe dp lun theo phuang thang dung trung binh bien doi t u 0 d i n 68 mm/nam, va cdc vung b i l n dang Idn nhdt tuang ung vdi ba khu vge d quan Hoang Mai, qugn Hd Ddng - Thanh Xuan vd huygn Hodi Dde- T u Liem.
Nghien edu nay ehi ra rang phuang phdp phan tfeh chuoi so ligu da thdi gian cd hieu qua doi vdi cae khu vgc nai cae cdng trinh nhan tao chiem u u the nhu trong mdi trudng dd thi. Nhung doi vdi eac cdnh ddng ndng nghigp, vigc xac dinh IGn trd nen khd khan han do thilu ede vgt tan xg. Trong trudng hgp nay, can thiet phdi phoi hgp mgt so phuang phap giao thoa radar d l ed k i t qua phan tich b i l n dgng tot han.
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Ngay nhan bai: 12/5/2015.
Ngay nhan bai sira lan cuoi: 15/6/2015.
