^ ^ _ KHOA HOC VA CONG NGHE M O
"^NGHIEN CUU BIEN PHAP XUTLY HAM SAP
T A I CONG T R i N H T H U Y D I E N B A N COC
KS. DO XUAN HOI Cong ty Xay dyng Song Da 10
1. Khdi qudtvf cdng trinh Thuy dien Ban Cdc Cong trinh thuy difn Ban Cic ndm tren suli Nam Giai thupc phu luu eua song Hilu trfn ^ a ban xd Chau Kim, huyen Qui Phong, tfnh Nghf An.
Suli Nam Giai tinh din tu vi tri dap trdn cd dien tich luu vyc la 150 km^ vdl ting chilu ddi dong chinh la 20 km.
Cong trinh thuy dien Ban Cic vdi nhifm vy ehinh la phdt difn len ludi dien quic gia a clp difn dp 110 KV, Vdi san lugng difn trung binh hang nam la 80,55 trieu kWh, thuy dien Ban Cic dam bao In dinh clp dien eho ludi dien 110 KV va eai thien dang k l chit lugng difn eho eae huyfn Qui Phong, Quy Chau, Quy Hgp,
Cum nha may gIm c6 tuyen dudng hdm ddn nudc CO chilu ddi 3100 m tu phia cua nhan nude din nhd may vdi ba to may mdi td may cd cdng suit la 6 MW eong suit lip may la 18 MW.
C6ng trinh dugc khdi cdng vao cudi nam 2005, do Cong ty C l phin Thuy difn Qui Phong thudc Ting Cong ty Xay dung Ha Ngi lam chij dau tu.
Ddy Id e6ng trinh thuy difn vua va nho dugc xay dyng tren dia ban cua tmh Nghf An, cdng trinh vdi tuyin him ddn nude ddi 3100 m vdi dien tich thilt k l 8,80 m^ bao gdm 1 hdm phy vdi ba hudng thi eong
Theo thilt k l , tuyin nang lugng nam trong viJng dit da HA vd dd IIB, Tuy nhien dilu ddc biet d cdng trinh ndy do chinh la khi thi c6ng him hudng eua nhan nude tu ly trinh 0-1-42 thi gdp sy c l vao thang 09 nam 2007,
2. Sy c6 hdm sap tai Thuy dien Ban Ode Trong qua trinh thi cdng din ly trinh 0-^40 thi bit dau xuit hifn c6 ldp bun nhao ro rl vao phia noc cua hdm. Hifn tugng nay xay ra^khdng lien tuc. Khi khoan n l min tiln guang da n l ra co hien tugng bun nhao rd rf xen kep ea tdp bun, dit, cat. Tuy nhien dan vj thi cdng da khong chCi y din hifn tugng ndy nfn vin tilp tye khoan n l min tiln
guang vdi chilu dai 2 m cho 1 chu kJ. Ngay sau k i t thuc ehu ky khoan nd thi b i t ddu c6 hi^n tugng Idp bun, dit, cat chay tu phia n6c him vdi luu lugng ngay cang Idn vd chi sau hai glo' thi h i m sap.
Lugng bun, ddt cdt da l i p todn bf tuyin ham ddy lugng bun ddt khoang 30 m ra din tan cira nhan nudc. Rit may tren thyc t f da khong xay ra tai ngn dang tile v l ngudi. S l lugng bun, dat, cSt chay vdo l i p todn bd cdng trinh khoang 930 m', ddy vf hai phia cua dudng hdm.
Chilu dai sap toan tuyen tu LT 0+38 din 1]? trinh 0+72 chilu cao ma khdi bun, dit, eat chay vao cao tdi 20 m (sd lieu tren dugc cung c l p sau khi C6ng ty Xdy dyng Sdng Da 10 xu ly hoan thien).
Trudc sy c l tren dan vi thi cdng, chu diu tu va dan vi tu vin giam sat vdn khdng danh gia lgi vung dia chit ndi tren ma vdn d l nguyfn hifn trang, Ddng thdi, cac dan vj lien quan lgi tilp tuc de dan vj thi eong triln khai theo hudng thu 2 tu ly trinh 0+
78 trd lai v l phia thugng luu.
Budc ddu khi thi cdng day vdn Id vCing dd In i^nh xong khi thi cong d i n ly trinh 0+76 thi bit diu xuit hien gilng nhu da neu tai ly trinh 0+40. LCie ndy thi dan vj thi cdng da nhanh chfng lip todn bf guang him bing bao tai cdt, ludi thep, bf tfng phun d l lip kin mat guang chd xu ly. Do dd tai hudng thi cflng nay kh6ng co sy cd nguy hilm nao xay ra.
3. Nguyen nhan cua s y cd sap hdm ThOy dien Ban Cdc
Tren ca sd nghien euu thuc te cd t h i chi ra mfit s l nhdm nguyfn nhan cc ban gay nfn sy c l s§p him Thuy difn Ban Cic nhu sau:
• Cac nguyen nhdn do cdng tac khao sat ^a ehdt dugc thyc hifn chua chinh xac;
•:• Cac nguyen nhdn do dan vj thi cdng chti quan thilu kinh nghifm trong qud trinh thi cdng;
•:• Mdt sd nguyen nhdn khdc.
3.1. Nguyen nhan do cong tac khao sat dja chat dwg^ thyc hign chwa chinh xac CONG NGHIEP MO S6 5 - 2 0 1 4
KHOA HOC VA C D N G NGHE NIO _ ^ ^
Theo tai lifu dja chdt do Cdng ty Co phin Tu vdn difn 1 khao sdt thi ddy Id vung dit da I n djnh khi tuyin dudng ham di qua do Id dit da HA. Tdc gia xin dugc trich nguyen vdn trong Ban thuyit minh tdi lifu thilt k l ky thudt "Theo klt..qua khoan khao sat dia chit trfn tuyin dudng him-cho thdy dogn diu hdm ddi 73 m ndm trong Idp dat dd Granit IIA eung trie, dogn con lal cua hdm nim trong dit da IIB cung chdc". Tuy nhien, do dilu kifn kinh phi c6n han ehl eho nen sd lugng 16 khoan tham dd khong du d l du bao dugc vung dia ehdt bit Igi, su biln dli cua tinh chit ca ly cua ddt dd do phong hoa, vd nhau, cung nhu su xuit hifn cua tui bun dat phia n6c cua hdm.
Do do khi thi edng din ly trinh 0+42 thi gap vung dia chit ylu ndi trfn nen dan din sy ed.
3.2. Nguyen nhan do don vj thi cong chu quan thieu kinh nghiem trong qua trinh thi cong Khi thi edng din ly trinh 0+40 khi bit ddu xudt hien Idp bun nhao r6 rlvao phia n6c cua hdm, mac du hien tugng nay khdng lien tue, ding thdi khi da n l ra ed xen kep vdi ca ldp bun, ddt eat.
Trudc hien tugng tren nlu mpt dan vj thi edng CO kinh nghifm se dung lai d l xem xet, ding thdi dua ra dugc ede bien phap thi e6ng phu hgp, d l thdm dd nhu tiln hanh khoan n l nho vdi chu ky tiln guang dao dpng td 0,3^0,5 m ding thai su dyng bien phap ehia guang df thi c6ng,
Trong qua trinh chia guang nlu tilp tuc eo hifn tugng bit thudng dien ra thi se nhanh chong lip guang lgi d l yeu clu dan vj tu vin khao sat danh gid Igi vung dja chit noi tren d l co phuang an xu ly kjp tiidi. Tuy nhien trudc dung trudc hien tuang neu tren dan vj thi cong vdn tiln hanh khoan no todn tilt difn vdi chilu ddi tiln guang la 2 m, tu d6 su c l da diin ra, Dilu nay cho thiy dan vi thi edng da chu quan thieu kinh nghiem trong xu ly trong qud trinh thi cong cac cdng trtnh ngdm khi thdy hien tugng bit thudng kh6ng ndm trong diln giai dja chat.
3.3. Mgt so nguyen nhan khac
Ngoai hai nh6m nguyen nhan ca ban fren, tren thuc t l c6n c6 mpt s l nguyen nhan khac eung gdp pndn tgo nen sy c l tgi dudng hdm Thuy dien Ban C6c.
*> Trudc sy e l noi tren dang le dan vj thi eong, chu diu tu cung nhu tu v i n giam sat phai ngii Igi 6h dua ra cdc bifn phdp xu ly. Tuy nhien Ca quan Chu diu tu cung nhu Dan vj Tu vin gidm sdt da khfng ngii Igi 6e ban cdc bifn phdp xu ly nhu dilu khao sdt Igi viJng dja chit ndi tren d l tu dd dua ra nh&ng dilu chinh phu hgp cho nha thiu trong qua trinh thi c6ng. md van tilp tye cho dan vj thi cdng triln khai theo phuang an hudng sd 2 ti> ly trinh:
0+78 din ly trinh 0+76 Dieu nay the hien sy quan
ly- ylu kfm thieu kinh nghifm cua Chu dau tu cQng nhu Tu vdn gidm sat trudc susy- c l ndi tren;
• Do kinh nghifm thi cdng cdn 1<em trong qua trinh phdt hifn thiy hien tugng bit Ihudng ciia vung dja chit di qua. Cung nhu dua ra cdc bien phap thi c6ng khdng hifu qua, ddng thdi nang lyc thi edng khdng ddp ung dugc yeu edu thyc t l , din din khfng thf xu ly su c l tren mot cdch hifu qua Tu do Chu diu tu phai mdi gpi dan vj thi c6ng khac c6 kinh nghifm cung nhu du nang lyc han d l thay t h i nha thdu chinh xO ly sy e l n6i tren.
3. Mpt sd giai phap xi> ly s y cd sap hdm Trudc sy ed neu trfn Chu Ddu tu la Cong ty C6 phin Thuy dien Qui Phong thugc Ting C6ng ty Xay dung Hd Npi da d l nghj nhd thiu ehinh, cung nhu mpt s l nha thiu phu Id cac cong ty cd kinh nghifm din d l tham gia ding thdi dua ra cdc bien phdp khdc phuc.
Mac du nhd thau chinh va cac nhd thdu phu dua ra rit nhilu giai phap, nhung sau khi tiln hanh thi c6ng thi diu kh6ng t h i tifn hanh xu ly dugc Trudc tinh hinh d6 Chu diu tu da tiln hanh mdi C6ng ty Xay dung Song Oa 10 thupc Tdng CPng ty Xay dyng S6ng Da vdo d l xu ly. Bdi vi, day Id dan vj thi cong co rit nhilu kinh nghifm trong xu ly cac su ed v l hdm thuy lgi thuy difn, giao thong dac biet Id xu ly su c l tuyin him ddt thupc cum cong trinh Hdm dudng bp qua deo Hai Van.
Sau khi khao sat toan bp doan su c l tgi hien trudng, Cong ty Xay dung Song Da 10 da d l xuit cac nhom giai phap khic phuc sy c l cy thi nhu sau:
•:• Cae giai phap c6ng nghf xu ly su c l ;
•;• Cac giai phap c6ng nghe thi cong;
•> Cae giai phap efng nghf ching glO;
• Cac giai phap c6ng nghf phu trg khac, 3.1. Cac giai phap cong ngh$ xii iy SLF c6 Trfn ca sd xae dinh duge nguyen nhan cua hifn tugng sap ham thuy difn Ban Cic la do vung dja chit phia ndc cua ham bj phong hoa manh c6 ehua nude vd bun dit. Tu day, Cdng ty Xay dung Sdng Dd 10 da nghien euu cae bifn phap d l gia eudng I n djnh cua khli dat da phia n6c, ding thdi lip toan bp guang hdm va xu iy vung sgt Id tren co sd cac giai phdp nhu sau:
• Trift tieu nguIn nudc mat chay tryc tilp vo khu vyc dfnh hdm, chuyin ngudn nude mdt nay sang luu vye khac;
^ <• Gia eudng on djnh cua khli dit da phia noc him bdng phuang phdp ca hpc (su dyng vi neo vugt trudc...),
<• Gia cudng I n djnh khli dit dd phia n6c him bing phuang phdp h6a hpe (phuang phdp silieat
CONG NGHIEP MO sd 5 - 2 0 1 4
KHOA HOC VA CONG NGHE MO
h6a; phuang phap su dyng cae loai nhya dinh ket tdng hgp...);
• Gia cudng I n djnh khli dit da phia n6c him bing phuang phap vat ly (phuang phap lam chat dit da bing dien; phuang phdp ddng bang nhan tgo.,.);
• Gia cudng I n djnh khli ddt da phia ndc hdm bing phuang phap h6a-ly (phuang phap xi mang hda;
phuang phap set h6a; phuang phdp bitum h6a);
• Phuang phap h6n hgp gia cudng (phuang phap t l hgp theo mgt nguyen t i c ndo d6 cac phuang phap gia cudng nhu da neu d tren),
Tu ca sd d6 Cong ty S6ng Da 10 da lua chpn triet tieu nguIn nudc mat chay true tilp va khu vuc dfnh him, chuyin nguIn nude mat nay sang luu vyc khac, ding thdi su dung phuang phdp hdn hgp gia cudng dat dd phia n6c cua hdm su dyng
"phuang phap phun xi mang hoa, bdng cac 16 khoan ldn f105 cdm cac dng thep f76 chilu ddi 6m d l phun xi mang ding thdi cac dng thep f76 dugc su dung nhu mgt dan neo vugt trudc tao su I n dinh phia trude guang him", la phu hgp nhdt, bdi mgt s6 phuang phap van mang tinh ly thuyit va ehua tung dugc dp dung a Viet Nam, mat khde do dilu kien tgi hien trudng vdn ehua t h i ung dyng dugc cong nghf n6i tren.
Uu difm viec lya chpn phuang phap hon hap phun xi mang h6a, bing cac 16 khoan ldn f105 elm cac Ing thep f76 chilu dai 6m d l gia co I n djnh dit da phia n6c ham do la: Khi xi mang hda ddt da bun phia n6c cua ham se lam eho cac moi lifn kit cOa vu'a vdi ddt dd bCin phia ndc cua hdm, tgo thanh mpt vong chong tu vgt lieu "ddt da-xi mang"
c6 kha nang mang tai tao su I n djnh ban diu cho vung sat Id. Cac 16 khoan f105 dugc elm bing cac Ing thep f76 vdi chilu dai 6m dugc su dung nhu mpt dan neo vugt trudc tao sy I n djnh phia trudc guang hdm trong qua trinh thi cong cac bude tilp theo.
Nhuge dilm eua phuang phap neu tren do la:
Khi khoan eae lo khoan Idn vdi chieu dai 6 m trong dilu kifn chat hep (do dien tich guang hdm nho) se trd len rdt khd khan, t i n nhilu thdi gian, nguy ca xay ra ldp cac lo khoan la rdt ldn, khd khan khi khoan bdng khoan tay, phai sLf dung may mde dgc Chung de tiln hanh khoan va lap ong thep.
v l trinh tu edng tae khoan, l i p dung 6ng thep va phun xl mang gia c l tai c6ng trinh thuy difn Ban c l e dugc thyc hien nhu sau:
• Bude mpt: tiln hanh xue bic toan bp khdi lugng biin dit cat chay din ly trinh 0+20 bdi toan bp khu vyc nay df u ndm trong vung gia c l dn djnh.
Tuy nhien trong qua trinh xuc bdo khi thiy cd hifn tugng bun cat chay ra thi ldp tuc x l p bao tai cat
ldp todn bd guang hdm rai ludi thf p phun bf tdng gia cd tgm.
• Budc hai: tiln hanh khoan tgi cdc vj tri dd xdc djnh dudng kinh lo khoan F105 chilu sdu 6 m theo dpc ndc hdm, ldp dgt dng thep va tifn hdnh phunxi mang M300. Khi tiln hanh bam xi mang hoa ^i iSlu chfnh dp luc bam cung nhu ty Ie N/X (N/X,^
If nudc tren xi mdng) tuy thufc vao Iuu Iugng cua may bam trong qud trinh phun, phun d i n khi jugrg xi mang khdng eon bam dugc thi tiln hdnh thao may. Quy trinh thyc hifn khoan l i p dat lng,cung nhu phun xi mdng dpc theo ndc film dugc thire hifn mdt each nghiem ngat trudc sy giam sdt cua Chu d i u tu eung nhu Tu v i n Giam sat
3.2. Cac giai phap cong nghe thi cong Sau khi gia eudng I n djnh eua khdi dit da cua vLing syt Id dan vj thi edng da thyc hien mpt so giai phap v l cdng nghf thi cdng nhu sau:
• Thu nhit tiln hanh tiln guang bing bien phap chia guang vdi chilu dai budc ching la 0,3 m. Qua trinh tiln guang vdi khoang each nho cd tde dyng: tao su I n djnh cua guang him vd vda co t h i quan sat dugc nhung hien tugng bit thudng ed thi' xay ra. Vife chia guang d l lai toan bf phia dit da, cat, bun tinh tu tim h i m tra xuing coi nhu' mpt try bao vf, dam bao khong cho lugng bOn dit, cat chay diy ra tiJ' hai ben hfng cung nhu phia ben trong guang hdm. Ddng thdi viec chia guang cung Iam cho cong tdc thi cdng dyng vi ehdng tgm dugc thuan Igi vd de dang han;
• Thu hai trong khi tiln guang nhOng viJng dit da ylu se su dyng khoan tay hoac may khoan him d l dye, nhii'ng vung khdng the duo bang khoan tay hoae may khoan ta phai su dung bien phap khoan n l nhd, hogc n l Ip. Vife khoan n l nhd hoac no Ip vdi chieu dai ti> 0,3 m se idm giam sdng no gay anh hudng d i n vung ddt dd bao quanh,tgo su on djnh cho cdng trinh nglm.
3.3. Cac giai phap cong nghe chong git^
Cde gial phap cdng nghf chdng giu- chu ylu dl xuat su dung tgi day bao gIm:
• Su dyng vi ching linh hogt v l kich thudc ding thdi sau khi ddo chia guang vdi buac ching 0,3 m:
+ Budc mpt tiln hanh dyng yi chong vdl khoang cdeh 0,3 m, khoan neo vdo 2 vach ciJa him vdi chieu dai I m djnh vi vi ching on djnh, tiln hdnh rai ludi thep phun be tong gia c l vi chong;
+ Budc hai sau khi dyng xong vi chong | ndc cua hdm tiln hanh dao bai 2 phia chdn cQa v ching, khoan hai Id khoan neo f42 trfn nin 6i theo djnh vi cCia cde l5 chd trfn t i m thfp din hudng chieu sau moi Id khoan Id 1,05 m. DdttlrtI
III, l i c i i
iphsn cDavT
CONGHGHIEPIVIOS0 5-2014
KHOA HOC VA C O N G HGHE MO thfp dSn hu'dng vdo vj tri thilt k l ddng d t thep f18 CII L=1,1 m vOa neo M300, hdn t i m ddn hudng vdo c6t thfp neo tiln hanh n i l chdn vi ching vd phun bf tflng gia c l M200;
+ Budc ba tiln hdnh xuc bic vgn chuyin viJng dit dd tCr phia tim him d i n nin vdi ehilu ddi khdng qud 0,3 m;
• Tilp tye ddo va Idp dyng vdm 112 lap Iai budc mft cho den budc ba df l i p vdm IT2 thu hai;
• Tilp tye ddo va Idp dyng vdm 112 Igp Igi budc mdt cho din budc ba d l lap dyng vdm 112 thu ba. Cu nhu t h i d i n hit chilu dai mflt chu ky 4 m thi Igi tiln hdnh khoan ldp dung Ing thep f76 ehilu dai 6 m, phun xi mang gia e l tgm, khoan nf min cung nhu cde budc dyng vi ching phai thyc hifn nghiem nggt theo cae giai phdp nhu trfn. Cac gial phdp dugc lap Igi cho d i n hit dogn sgt Id qua vung sgt Id.
3.4. Cac giai phap cong nghe phu trgf khac Cde glai phdp cong nghf phy trg khde bao gflm mft s l giai phdp chinh sau:
• Phai thudng xuyfn sl> dyng mdy todn dgc d l lifn tye quan trie, cO- sau mdt ehu ky dyng vi ching vdi bude ching 0,3 m thi Igi phai quan trdc mft Ian, dyng vi ching den ddu thi quan trie din df d l c6 t h i dy bdo cung nhu phdng ngda cdc biln dgng c6 t h i xay ra trong qua trinh thi eong;
• Dudng ham thuy difn Ban Cdc cd difn tich nho nhd thiu thi cong d day khoan n l min tiln guang bdng khoan tay, Hp cd t h i su dyng sdn cflng tdc trong qud trinh thi cdng hofc cd t h i khoan phin n6e trudc tinh tu tim him, rii mdi tiln hdnh xuc bic vf n ehuyin phdn tu tim din nin ham. Khi XIJC bic xong se tiln hanh khoan tilp phdn cdn lgi d l thyc hifn qud trinh tiln guong. Tuy nhien d l thyc hifn dugc I5 khoan vdi dudng kinh f105 vdi chilu sdu 6 m d l xi mang hda Iugng bun dit, cat phia n6c cua dudng hdm thi cin phai cd mdy dgc Chung chuyfn v l him. Vi the Cong ty Xdy dyng Sflng Dd 10 dd su dyng mdy khoan tu hdnh rocket 1 cin chgy bdng khi nfn kit hgp vdl khoan tay.
Mdy vii'a c6 tinh ca dfng cao c6 thf di chuyin mft cdch thudn Igi trong dilu kien chft h^p cua hdm;
• v l cdng tdc xiic boc su dyng mdy xuc giu bdnh lip cfl tinh ea dfng cao e6 thf di chuyin mft cdch thufn Igi trong vj tri chat hep,
Trfn ddy tdc gia cung clp bin nhflm giai phdp mang tinh khoa hpc vd thyc tien cao eua Cong ty Xdy dyng Sflng Od 10 dd dugc dp dynq thdnh cdng vd xu Iy mft cdch hifu qua cua dudng hdm cfing trinh thuy difn Bdn Cic trfn d|a bdn xd Chdu Kim huyfn Qui Phor>g fnh Nghf An. Sau han ba thdng thi cflng bdng kinh nghifm cua dan vj minh, vdi ndng lye ddp ung
dugc vdi tinh hlnh thyc t l don vf thi cflng ds, hodn thdnh mft each xuit sdc gfli thiu md Cdng ^ Cf phin thuy dien Qui Phong thufc Tflng Cdng ty Xay dyng Hd Nfi giao cho. Dam bao chdt Iugng cung nhu t i n df eua cdng trinh, gdp phin cho cdng trinh thOy difn Ban Cic sdm dugc hoan thdnh hda vdo ludi difn qudc gia ndm 2009.
4. K i t luan
• Cflng trinh thuy dien Ban Coc la mft cdng trinh thuy dien vdi tuyin hdm dp Iyc ddi 3100 m, tuy vdi dien tich khai ddo nhd nhung Igi di qua mgt vLing dja ehdt cd dilu kifn hit sue phuc tgp. Vdi chilu dai gin 40 m di qua vung bun nhdo, dit, cat chay^ Vung dja chdt dae bift ndy khfing Idn nhung da d l Igi nhOng bdi hgc rdt quan trpng d l i vai cdc dan vj thi cfing, cung nhu edc nhd khoa hgc.
• Vife phdt hifn ra cac hifn tugng bit thudng trong qud trinh thi edng nhu khi dit da khoan no cd hifn tugng nhu k?p hbn cdt, hay cd sy rd rf cua nude nglm, cdt chay. Id bai hpc kinh nghiem d l cd t h i du bdo hofe phdng ngCra trdnh nhung rui ro.
• Vife xu Iy dogn hdm qua vung dja chit ylu cDng Id bai hge Idn dfi vdi Chu D i u tu vf cflng tac lya chgn cde nha thdu c6 du nang Iyc v l mdy mde thi c6ng hifn dai, du kinh nghifm sang tao vdi dfii ngQ ky su, cdng nhan Idnh nghe c6 trinli df, kinh nghifm chuyfn mdn eao, d l dua ra ede bifn phdp xu ly trudc vd sau thi edng cflng trinh nglm mdt cdch hifu qua nhit. Trdnh nh&ng nha thdu yfu v l ndng Iyc, cung nhu trinh df chuyfn mfln thip khi ddm nhgn thi edng edc cdng trinh cua minh, Idm chdm tiln dp va gdy ra mft so nhung hdu qua khd ludng lam tang gid thdnh cho d i u tu dy dn.
• Bifn phdp thi cfing eua Cfing ty Xdy dyng Sfing Da 10 dugc trinh bay mft each cy the nhu trfn eung chlnh Id giai phap mang tinh khoa hpc, hifu qua eao, cin dugc dp dyng mgt cdch rfing rai trong qua trinh xO ly cdc sy c l , ddc bift trong qud trinh thi c6ng xi> ly sy e l hogc qua nhOng vung dja chdt ylu. Bifn phdp nay nhu mgt cuon s l tay de dOng cho edn bg chf huy, can bf ky thudt cung nhu cdng nhdn cua nhOng dan vj dgc thu, khi ttii edng cae cdng trinh nglm ndi ehung d nudcta hifn nay.D
Ngirai bien t$p: Vo Trgng HUng
The paper shows some technical solutions to repair the incident which had occurred in tunnel at Hydropower Project Ban C6c.
CDNG NGHIEP MO S6 5 - 2 0 1 4
