PHAN II - XAY DUNG VA B A O VE CONG TRINH... 429
OAC TRUNG KY THUAT VA PHU'QNG PHAP XAC DINH CAC TiNH C H A T c d LY CUA MANG C H 6 N G THAM
PHUC v y XAY DI/NG CONG TRINH THUY LQI
PGS.TS. Dinh Vu Thanh"' PGS.TS. LeMinh'^'
Tdm tit:
Su dung vat lieu mdi de chong thim, tao cac hd chira nudc nhd dugc sCr dung nham chura nudc cho ndng nghiep, dan sinh va cac nhu c i u khac ngay cang tang.
Khi SLP dung cac vat lieu mang chong tham cdng trinh thuy Igi thay the vat lieu set, bentonite v.v... can hilu cac dac tinh ky thuat, pham vi irng dung cung nhu phuang phap thCr cac dac tinh de lua chgn va su' dung loai mang chdng thim phii hgp vdi dieu kien cdng trinh.
Bai viet nay nham gidi thieu mdt sd ket qua nghien ciru, de xuit phuang phap lua chgn va xac djnh cac tinh chat ca ly cua mang chong tham phii hgp, phuc vu xay dung cdng trinh thuy lgi loai nhd, cd dung tich dudi 50.000 m^ nudc.
Tif khoa: dja ky thuat (DKT), chong tham (CT), mang chdng tham, dac trung ky thuat, tinh chat ca ly, phuang phap thi nghiem.
Summary:
TECHNICAL CHARACTERISTICS AND METHOD FOR DETERMINATION OF THE PHYSICAL PARAMETERS OF GEOTMEMBRANE FOR WATER
RESOURCES CONSTRUCTION
New materials for anti-filtration and creation of small reservoirs have been used increasingly during recent years for water storage to serve irrigation, water supply and other water use purposes. When geomembrane is used, it is essential that the technical characteristics of materials and their applicability are known by designers so that appropriate materials and designs, and appropriate methods of construction and maintenance are proposed.
This paper introduces some research results on methods for determination of physical parameters of geomembrane and for selection of appropriate impermeable geotextile materials used for construction of reservoirs with storage capacity of less than 50,000 cubic meters.
Keywords: geology, anti-filtration, geomembrane, technical characteristics, physical parameters, test method.
'" Vu Khoa hgc Cong nghe va Moi trirong '-' Vien Khoa hoc ThiJy lgi Viet Nam
LMODAU
Hien nay viec sir dyng mang chdng tham thay the cho dat set, tham set, bentonite v.v... trong cac ket cau chdng tham cua cdng trinh thuy Igi nhu hd chiia, ao chiia, be treo v.v... tuong ddi phd biln. Ndi dung phan nay gidi thieu dac tinh ky thuat va phuong phap thi nghiem xac dinh cac chi tieu dja ky thuat de ap dyng trong thiet ke, thi cdng, van hanh cac cdng trinh thuy lgi ndi tren cd dung tieh dudi 50.000 m nudc.
Ddng thdi ciing cd the tham khao tai lieu nay khi thiet ke thi cdng ket cau chdng tham bao ve mai dap (dap dat, dap da v.v...) hoac lam ldp chdng tham trong cdng trinh xif ly chat thai, cac md khai khoang, cac nha may che bien dau md v.v... chdng d nhiem ngudn nude, bao ve mdi trudng, ket hgp vdi sir dyng tai lieu chi dan do nha may san xuat mang chdng tham cung cap, de tdi uu hoa viec sir dyng mang chdng tham.
2. MOT S6 KHAI NIEM VA DAC TRU'NG KY THUAT V^ MANG
C H 6 N G T H A M2.1. Djnh nghTa
Mang chdng tham la san pham polyme tdng hgp d dang cudn hoac tam, cd he sd tham rat thap (K = 10"'^ den 10""'cm/s), dugc sir dyng de chdng tham cho cdng trinh.
2.2. Thanh phin clu tao mang chdng thim
Mang chdng tham che tao tir polyme va eac chat phy gia. Ty le phdi lieu eae chit tuy thudc vao don pha che ciia nha san xuat hoac theo yeu cau ky thuat eiia loai cdng trinh cy the.
Loai mang HDPE (High Density PolyEthylene) cd thanh phin co ban gdm: 95% + 97% polyme; 2,0% + 2,7% bdt than; edn lai la chat chdng tia cyc tim, chit chdng oxy hoa va chat dn dinh nhiet.
2.3. Dac tru'ng cua san pham
Mang chdng tham dudi dang cudn cd trgng lugng tir 1300 kg/cugn din 1400 kg/cudn.
Nhan mac dugc dan hoac in tren san pham phai cd cac thdng tin sau: Ten, chung loai san pham; Kich thudc: do day (mm) x dai (m) x rgng (m); Sd Id, sd seri; Ngay, thang, nam san xuat; Ten hang (hoac ten nha may), nudc san xuit; Dia chi, dien thoai, fax, email.
Kem theo san pham la chimg chi chit lugng hang hoa, cac tai lieu hudng din lip dat mang chdng tham va kiem tra chat lugng cdng trinh.
2.4. Cac dac tru'ng ky thuat co- ban ciia mang ch6ng thim
- Do day (Thickness): La khoang each do bing mm hoac mils giira hai ban mat
ciia thiet bj do khi tiip xiic vdi hai mat ciia mang chdng thim vdi lyc ep khdng ddi la
20 kPa trong thdi gian 5 giay.
PHAN II - XAY DtJ^JG vA BAO VE CONG TRINH... 431
- Ty trpng (Density): La khdi lugng trong khdng khi cua phan vat lieu khdng thim nudc, d 23°C (tinh bing kg/m^ g/cm^; g/cc);
- Chi sd chay deo (Melt Flow Index): g/lOphiit (g/lOmin);
- Cudng dp chju keo (Tensile Strength): La irng suat ldn nhat tren mat cat ngang nhd nhat ban dau cua mau thi nghiem trong qua trinh keo, tinh bing KN/m; N/mm;
Lbs/in (Pounds-force);
- Do gian dai (Elongation): La ty sd giira chieu dai ciia mau tai thdi diem bat ky trong qua trinh keo va chieu dai ban dau cua mau thi nghiem, tinh bing %;
- Do ben khang xe (Tear Resistance): La lyc lam rach mang chdng thim d tdc dp xe 50 mm/phiit, tinh bang N hoac Lbs;
- Dp ben khang thiing (Puncture Resistance): La lyc lam thiing mang chdng tham khi cho thanh chpc hinh try cd dudng kinh 8mm xuyen vudng gdc vdi be mat mang vdi tdc dp 300 mm/phut, dnh bang N hoac Lbs.
- Ham lugng cae bon (Caebon black content): %.
3. PHU'aNG PHAP LU'A CHQN VAT LIEU VA THI NGHIEM XAC DINH CAC TJNH C H A T C a LY CUA M A N G CH6N"G T H A M PHUC VU XAY DU'NG CONG TRJNH THUY LQI
3.1. Phu'O'ng phap lira chon vat lieu
Trudng hgp ngudi thiet ke khdng chi dinh dich danh loai mang CT can sir dung ma chi dua ra yeu cau ky thuat ciia mang, viec lya chpn vat lieu phai qua cac budc sau:
Buac 1 - Thu thap thdng tin: Tren co sd danh myc gidi thieu san pham ciia nha san xuat cung cap, chpn mdt vai loai vat lieu cd dac tinh ky thuat tuang duong hoac tdt hon so vdi thiet ke.
Buac 2 - Kiem tra: lay mau tir nhdm vat lieu lya chpn giri tdi cac phdng thi nghiem hgp chuan de xac djnh cac tinh chat co ly. De tang do tin cay, nen ddng thdi giri mau den cac phdng thi nghiem khac nhau.
Buac 3 - Lya chgn nha cung cap: Tir cac sd lieu thi nghiem kiem tra mau vat lieu, kit hgp cac yiu td khac nhu: kha nang cung cap cua nha san xuat, gia thanh san pham v.v... chgn loai vat lieu dua vao sir dyng.
Trudng hgp trong ban ve thiet ke ghi rd ten loai vat lieu can sir dyng thi viec lya chgn vat lieu bat dau tir bude 2.
3.2. Phu'ang phap thi nghiem xac djnh cac tinh chit ca ly mang chdng thim Cac chi tieu co ly va phuang phap thi nghiem mang CT neu d bang 3.1. Viec lya chpn chi tieu de thi nghiem do tu van quy djnh cho tirng loai cdng trinh cu the.
Bang 3.1. Cdc chi lieu vd phuang phdp thi nghiem mdng CT
STT 1 2 3 4 5 6 7 8 9 10
Chi tieu Op day tieu chuan Ty trpng
Cudng dp chiu keo tai diem 6<A Cudng dp chiu keo tai diem uon Dp giap dai tai diem (Jul Dp gian dai tai diem uon Op bdn kh^ng thiing Op bdn khang xe Ham lupng caebon Chi s6 chay deo
Phuang phap thi nghi§m ASTM-D5199
ASTM - D792 ASTM - D638/ DanglV ASTM - 0638/ DanglV ASTM - 0638/ Dang IV ASTM - 0638/ Oang IV
ASTM - 04833 ASTM - 01004 ASTM-01603 ASTM-01238
Dan vj do mm
mil g/cm^
kg/m^
KN/m KN/m
%
%
N N
%
g/IOmin
3.2.1. Phwffng phdp xdc dinh dp ddy tiiu chudn mdng CT
Dp day mang CT dugc xac djnh theo tieu chuin ASTM-D5199.
- Phuang phap do: Do day tieu chuan ciia vat lieu dja ky thuat tdng hgp dugc xae djnh bdi khoang each giira hai ban mat cua thiet bj do khi tiip xuc vdi hai mat cua mang dja ky thuat vdi lyc ep tieu chuan 20 kPa trong thdi gian 5 giay.
- Thiet bj thi nghiem:
-I- Khudn lay miu: Chi tao bing thep, hinh trdn dudng kinh 75 mm (H.3.I).
Dong ho do
H.3.2. Thiet bi do H.3.1. Khuon lay mdu
PHAN II - XAY DUNG VA BAO VE CONG TRINH... 433
+ Thiet bi do: eac bd phan ciia thilt bj do (H.3.2), gdm ddng hd bach phan cd do chinh xac 0,02 mm; Ban ep tren, chuyin ddng len xudng, hinh trdn dudng kinh 56,4 mm (2,22 in) phia tren chit tai.
Khi do do day mang chdng tham, ap lyc len mau do la 20 kPa ± 0,2 (2,9 ± 0,03 psi); Chieu day tdi da eho phep eiia miu la 10 mm.
- Mau thi nghiem: hinh trdn, dudng kinh 75 mm. Lay mau bang dyng cy chuan (H.3.1).
+ Sd lugng mau do: 10 mau
+ Dieu hoa mau trong dieu kien: ap suat khi quyen; Nhiet dp: 21 ± 2 "C; Dp am:
60 ± 10%; Thdi gian: 24 gid hoac dugc tinh bdi thdi gian giira hai lan can lien tiep ma trpng lugng mau khdng thay ddi qua 0,1 % nhung khdng dudi 2 gid.
- Trinh ty thi nghiem: Qua trinh do do day mang CT dugc tien hanh nhu sau:
+ Chuan bi 10 mau da dugc dieu hoa trong dieu kien tren;
+ Dat tai trgng 20kPa len ban ep tren (ban ep di dgng);
+ Chinh thang bang ban ep dudi bang gigt nudc;
+ Chinh ddng hd bach phan ve 0;
+ Keo cin nang ban ep di ddng ddng thdi dat tam mau triing vdi tam ciia ban ep, tir tir ha cin nang, khi ban ep tren tiip xuc vdi mat miu tha can nang va bam ddng hd giay;
+ Chd 5 giay dpc chi sd tren ddng hd bach phan ke va ghi ket qua.
- Tinh toan kit qua: Chiiu day mang CT la gia trj tmng binh cdng ciia 10 miu thir
T = (Tl-HT2+...-HT10)/10,mm (3.1) 3.2.2. Phwffng phdp xdc dinh ty trgng twffng ddi vd khdi Iwffng riing ciia mdng CT
Sir dung theo tieu chuin ASTM- D792 dung d l xac djnh khdi lugng rieng ciia chit nhya rin d dang mang, cgng, dng va cac san phim tuong ty.
Chii thich:
- Ty trong tuang doi: id ty so cita khoi lirang trong khong khi ciia phdn vdl Hiu khong thdm nudc a 23 "C vd hiiu so cita khoi luong trong khong khi vd khoi lugng cua chinh no trong nudc tinh khiet khdng cd bot khi a cung nhiit dp. Ky hiiu Id Sp 23/23 °C, dan vi do: kg/in.
- Ty trong: Id khoi lugng Irong khdng khi ciia phan vgt lieu khong thdm meac a 23 "C. Ky hiiu Id D-\ dan vj: kg/m\
- Phwffng phdp do:
Xac dinh khdi lugng ciia mau thir trong khdng khi; Nhiing miu vao nudc cat, xac djnh khdi lugng cua miu trong nudc; Tinh ty trpng tuong ddi ciia mau tir dd suy ra ty trcng eiia mau.
- Thiit bi thi nghiim:
Can phan tich cd dp chinh xac 0,05%; Kep d l giii mau trong chat long; Vat nhan chim mau vao chit long (thudng diing cue chi) cd dac dilm: khdng bj an mdn trong
chat ldng, cd khdi lugng rieng khdng nhd han 7, cd be mat tron nhan, khdng sac nhgn;
dng chiia chat Idng cd khac vach do the tich; Nhiet ke cd do chinh xac ± 0 , 1 C; Nudc cat da loai bd hoan toan bpt khi.
- Mdu thir:
La nhiing mau, mieng rieng re lay tir vat lieu ed kich thudc va hinh dang bat ky, trpng lugng khdng qua 50 gr; Dieu hoa mau trong dieu kien tieu chuan, nhiet dp: 23 ± 2 ° C , d d i m : 5 0 ± 5 % .
- Trinh tir thi nghiim:
+ Do va hieu chinh nhiet do cua nudc trong dng ludng la: 23 ± 0,1 "C;
+ Can mau bang can phan tich chinh xac tdi 0,1 mg trong khdng khi;
+ Can trgng lugng mau, kep giii mau, vat nhan chim trong nudc.
- Tinh ty trgng twffng ddi cua mdu Iheo cong thwc:
Sp 23/23 °C = a/(a-(-w - b) (3.2) Trong dd:
a - khdi lugng thyc ciia mau trong khdng khi (khdng cd kep giir m i u va vat nhin chim mau);
b - khdi lugng thyc ciia mau va kep giii mau, vat nhan chim trong nudc;
w - tdng khdi lugng cua kep giii va vat nhin chim.
Khdi lugng rieng ciia mau dugc tinh theo cdng thitc sau:
D " = S p 23/23 °C x 997,5 ( 3 . 3 ) Trong dd: 997,5 la ty trgng ciia nudc d 23 "C
3.2.4. Phwffng phdp xdc dinh cw&ng dp chiu keo cua mdng CT
- Tieu chuin ASTM - D638 dang IV diing d l xac djnh cac tinh chit chju keo ciia mang CT cd chieu day nhd han hoac bing 4 mm;
- Tieu chuan ASTM -D638 dang V, dang II: ap dung cho mang CT cd do day < 7 mm (0,28 in);
- Tieu chuan ASTM - D638 dang III: ap dyng cho mang CT cd chiiu day tir 7 mm den 14 mm;
- Cac tinh chat chju keo cua mang CT bao gom: Cudng do chju keo tai dilm udn (cdn gpi la diem tdi han); Cudng dp chiu keo tai dilm diit; Do gian dai tai dilm udn va tai diem diit.
- Thilt bi thi nghiem, gdm: May keo van nang (md ta hinh H.3.3); Thilt bj do dp cang (Extension meter); Thudc do milimet (Micrometer): do dp day va chiiu rdng mau thir.
- Mau thi nghiem (Dang IV): Cd hinh dang tren hinh H.3.4 va kich thudc d bang 3.2.
PHAN II - X A Y D U N G V A B A O VE CONG TRINH.. 435 B6 cam bign lirr
img lircLoarlsplf Ngam kep mlii Dam chuyen dong
Hop digu khjgn
Hop so
Dam CO dinh
H.3.3. Mdy keo vgn ndng
i
w„
^
L„
G L D
JR(.
$ w
H. 3.4. Mdu thi nghiem keo dgng IV
Bdng 3.2. Kich ihuac mdu dgng IV
Kich thudc mlu W- chigu rpng mat cit dai hep L- ehidu dai mat cit dai hep Wo- chi4u rpng tong the miu Lo- chigu dai tong the miu G- Chigu dai do
D- khoang each ngam kep R- ban kinh dudng tron trong Ro - b^n kinh dudng tron ngoai
Dan vi mm
6 33 19 115 25 65 14 25
inch 0,25 1,3 0,75
4,5 1,0 2,5 0,56 1,0
- Trinh ty thi nghiem: Dieu hoa mau trong dieu kien tieu chuan, nhiet do: 23 ± 2°C, do im: 50 ± 5%., thdi gian: 40h.
- Diiu kien thi nghiem: Thi nghiem miu tien hanh dudi ap suat khi quyen, nhiet do 23 ± 2 "C, duy tri do im 50 ± 5%.
- Tdc do keo miu: Chgn theo bang 3.3. Gia trj, nhd diing cho mang CT tir polime nhan tao, dp dan dai nhd; ldn dimg eho mang chdng tham tir vat lieu gde cao su, do dan dai khi keo ldn.
Bdng 3.3. Chgn l6c dp keo mdu
Phan loai
Rin va ban rin (Rigid and SemiRigid)
Mgm ( NonRigid)
Dang miu 1, II, III thanh va ong
IV V III IV
T6c dp keo, mm/p hoac(in/min) 5 (0,2) ±25%
50 (2) ±10%
5 (0,2) ±25%
50 (2)+10%
1 (0,05) ±25%
10 (0,5) ±25%
50 (2) ±10%
500 (20) ±10%
50 (2)+10%
500 (20)+10%
Ddi vdi loai mang CT mem, mau thi nghiem ehe tao theo dang IV ed chieu day nhd hon hoac bang 4mm chpn tdc dp keo 50 mm/phut ± 10% (2 in ±10%).
- Tinh ket qua: Dd thj bieu dien quan he lyc keo va dp dan dai ciia miu do may ghi lai cd dang dien hinh nhu hinh H.3.5 (cdn gpi la dudng cong iing suit).
Lire keo, N
B
>-D6 gian dai, mm
H.3.5. Duang cong img sudt
Dudng cong irng suat cd nhirng dilm dac trung sau: Dilm udn (Yield point) hay
cdn gpi diem tdi han (diem A): La diem ma do gian dai tang trong khi iing suit keo
khdng tang; Dilm diit (break point): la dilm tai dd mau thi nghiem keo bj pha huy
hoan toan (diem B).
PHAN II - XAY DIJNG vA BAO VE CONG TRINH... 437
+ Tinh cudng do va do gian dai:
Cudng do chju keo tai diem udn (Tensile Strength at Yield point): la img suat xac djnh tai diem udn (gia trj A j ), tinh bang lyc keo tai diem udn chia cho be rdng nhd nhat cua mau. Don vj do la N/mm; KN/m hoac Lbs/in.
Cudng do chju keo tai diem dirt (Tensile Strength at break): la img suat ldn nhat (max) tai diem pha huy mau ( diem Bj), tinh bang lyc keo dirt chia cho be rpng nhd nhat ciia mau. Dan vi do: N/mm; KN/m hoac Lbs/in.
+ Tinh phan tram dp gian dai (Percent Elongation):
E(%) = L-Lo/LoXlOO% (3.4) Trong dd: Lo - chieu dai ban dau ciia mau tinh bang mm hoac inch;
L - chieu dai mau tai thdi diem bat ky trong qua trinh keo.
Neu: LA - chieu dai mau tai diem udn thi phan tram dp gian dai tai diem udn la:
E A ( % ) = LA - Lo/Lo X 100% (3.5) LB - chiiu dai miu tai diem diit (diem pha huy) thi phan tram dp gian dai tai diem
diit la:
E B ( % ) = LB - Lo/Lo X 100% (3.6) -I- Tinh dp cang thyc (dp gian dai tai diem bat ky):
Theo phuong trinh:
E=tdLIL = LnLIL^ (3-7) Trong dd: Lo - khoang each ban dau;
L - khoang each tai diem bat ky tren bieu dd.
3.2.5. Phwffng phdp xdc djnh dp ben khdng .xe cuu mdng CT
Tieu chuin ASTM-D1004 dung dl xac dinh siic khang xe ciia mang CT d tdc do keo (xe) 50 mm/phut (2in/min). Don vj do: N (Newton) hay Lbs (Pounds - Force).
- Thilt bj thi nghiem: Thilt bj xac djnh dp bin khang xe ciia mang CT la may keo van nang (xem hinh H.3.3).
- Miu thi nghiem: Hinh dang va kich thudc miu thi nghiem xac djnh dp ben khang xe cua mang CT theo tieu chuin ASTM - D1004 trinh bay tren hinh H.3.6.
+ Dp chinh xac ddi vdi dan vj do chiiu dai mau l a ± 0,002"(0,051 mm);
-I- Dp chinh xac ddi vdi gdc lugn ciia mau la ± 0,5°;
+ So lugng miu: Khdng it han 10 miu cho moi chiiu dgc va ngang cudn.
Diiu hoa mau trong diiu kien tieu chuin: Nhiet do 23 ± 2 "C; Do am 50 ± 5%;
Thdi gian: Khdng it hon 40h cho mdt chu ky.
Diiu kien thi nghiem: Nhiet do 23 ± 2 ^ ; Dp im 50 ±5%.
101,6
19,05
50,8 28,4 Ghi chu: kich thtrac ghi tren hinh ve la mm
H.3.6. Mdu thi nghiem khdng xe - kich Ihuac mm
- Trinh ty thi nghiem:
+ Chpn ngam kep mau ed thiet dien I in (25,4 mm);
+ Chpn tdc dp keo 50 mm/phut (2 in/min);
+ Do dp day cua mau thir, dan vj do micron hoac mil;
+ Lap mau do vao ngam kep mau sao cho dudng tryc ciia mau triing vdi dudng tmng tam ciia ngam kep mau;
-I- Sau khi hoan thien cac budc tren, tien hanh thi nghiem, cho may chay vdi tdc dp keo 50mm/phut;
+ Ghi gia trj lyc khang xe ldn nhat cua moi miu thir. Lyc khang xe dugc tinh bang N (Newton) hay lbs (Pounds-force).
- Tinh toan ket qua:
+ Dp bin khang xe cua mang theo moi chiiu (ngang, dge) la gia trj binh quan cua cac miu thir, xac djnh bing each liy tdng gia tri lyc khang xe ldn nhit cua cac mau thu chia cho sd mau thir.
T(N)= rri/n (i=l...n) (3.8) Trong do: n - sd lugng mau thi nghiem.
+ Trong trudng hgp khdng yeu ciu xac djnh dp bin khang xe theo moi chiiu, dp ben khang xe ciia mang la gia trj trung binh dp bin khang xe ciia 2 chiiu.
3.2.6. Phwang phdp xdc dinh dp bin khdng thung eda mang CT
Tieu chuan ASTM - D4833 xac djnh dp bin khang thimg ap dyng khi sir dung mang chdng tham cho dap, be chira nudc, diu, dung mdi v.v... trong xay dyng, kiln true va cac he khac.
- Thiet bj thi nghiem:
+ May keo nen van nang: xem md ta d hinh H.3.3.
PHAN II - XAY DIJNG vA BAO VE CONG TRINH.. 439 + Thiet bj kep mau: cd hinh tang trdng che tao bang thep cd hinh dang va kich thudc chi dan tren hinh H.3.7.
6R8mm
R100±0,025mm
< H R45±0.025mm
37±0.025mm 12mm
150mm
R8±0.Im ,
130mm 18mm 50±lmm H.3.7. Thiet bi kep mdu H.3.8. Thanh choc
+ Thanh chpc: che tao bang thep khdng gi cd hinh dang va kich thudc md ta d hinh H.3.8. Thanh chpc ndi tryc tiep vdi bd cam irng lyc bang ren, trong sudt qua trinh thi nghiem dien bien sire khang thiing ciia vat lieu hien thi tren man hinh may tinh hoac man hinh chi thj cua may thi nghiem.
- Miu thi nghiem, dugc che tao tir khudn lay mau hinh trdn dudng kinh 100 ± 0,5 mm. Sd Iupng tir 10 din 15 miu va dieu hoa trong dieu kien tieu chuan: Nhiet dp 21 ± 2 °C; Dp i m 65 ± 5%.
Thdi gian diiu hoa miu it nhit la 5h. Neu khdi lupng miu giira 2 lan can lien tiep khdng sai so qua 0,1% thi tien hanh thi nghiem.
- Trinh ty thi nghiem:
+ Lip m i u thir vao thilt bj kep miu sao cho tam eiia mau thir triing vdi tam ciia hinh vanh khan ciia thiet bj kep mau;
-I- Diiu chinh thilt bi kep miu de mat phang miu vudng gde thanh chpc va tam ciia miu tiip xiic vdi dau nhpn ciia thanh chpc;
+ Chpn tdc dp chay may la: 300mm/phiit ± 10 (12 ± 1/2 in);
+ Cho may chay va ghi gia trj lyc chpc thiing ldn nhat ciia timg mau thir.
- Tinh toan kit qua: Sire khang thiing ciia mang CT la gia trj trung binh cdng lyc chpc thung ciia tit ca m i u thir, dan vi do bang Newton (N).
T ( N ) = E P i / n (3.9) Trong dd: n - sd lugng mau thir.
4. K^T LUAN
Hien nay cd nhilu vat lieu mdi dugc nghien ciiu, san xuat, ap dung vao cdng trinh xay dyng. Cac loai vat lieu mdi nay cd nhilu tinh nang uu viet, khi sir dyng vao cdng trinh cy thi cin phai hilu rd dac tinh ky thuat cua vat lieu, cung nhu phuong phap thi nghiem xac djnh cac tinh chat ca ly cua chiing.
Ciing vdi sy ra ddi eua vat lieu mdi, cac phuang phap thi nghiem vat lieu cung dugc cai tiin va hoan thien hon. Trong tai lieu nay chiing tdi da lya chgn nhimg phuong phap phii hgp nhit, dl ap dung xac djnh eac chi tieu co ly cua mang chdng tham phuc vy xay dyng edng trinh thuy Igi.
Thyc tl da cd nhilu edng trinh thuy lgi sir dung mang chdng tham thay the cho dit set, tham set, bentonite v.v... trong cac ket cau chdng tham eua cdng trinh. Qua trinh thilt kl, thi cdng, van hanh khai thac, sir dung ciing cd mdt sd tdn tai can khac phuc, phan nghien cim tiep theo chiing tdi se de cap den cac khia canh nay.
Can sir dyng ddng thdi eac tai lieu ky thuat ve mang chdng tham do cac nha san xuat cung cap, ciing nhu cac tai lieu ky thuat lien quan de lya chgn, quyet djnh sir dung vat lieu, nham dat hieu qua cao ve kinh te, xa hdi va mdi trudng.
TAI LIEU THAM KHAO
[1]. Chi dan thiet ke va sir dyng vai dja ky thuat de Igc trong cdng trinh thuy Igi, nam 1996 - Bd Ndng nghiep va PTNT.
[2]. Tieu chuan Vai dja ky thuat - Quy dinh chung ve lay miu, thir mau va xir ly thdng ke, 14TCN 91 -1996, nam 1996 - Bd Ndng nghiep va PTNT.
[3]. Tieu chuan Vai dja ky thuat - Phuong phap xac djnh eac chi tieu ca ly, tir 14TCN 92-1996 din 14TCN 99-1996, nam 1996 - Bd Ndng nghiep va PTNT.
[4]. Vien khoa hgc Thuy lgi, 2007, Bao cao nghien ciiu xay dyng hudng dan sir dyng mang chdng tham trong cdng trinh thuy Igi.
[5]. Standard test method for tensile properties of plastics (D-638), USA, 2003.
[6]. Standard test method for measuring the norminal thickness of geosynthetics (D- 5199), USA, 2001.
[7]. Standard test method for index puncture resistance of geotextiles, geomembrans
(D-4833), USA, 1988.