KHOA HOC ^KE!ECB!I^B
NGHIEN CUtf TRONG PHONG CAI TAO DAT LOAI SET YEU PHAN B 6 T A I DONG BANG SONG CUtJ LONG
B A N G XI MANG DIA PHU^ONG
ThS. Vu Nggc Binh, GS.TS Nguyen Qudc Dung, KS, Vu Ngoc Hai Vien Thuy cdng PGS.TS ©o Minh Toan Truang dgi hgc Md- Dia chdt
Tdm tit: Kit qua nghien citu ddt logi set yiu phdn bd a cdc tinh An Giang, Tiin Giang, Hgu Giang. Bgc Lieu vd Cd Mau ddt ldn him co cd ham lugng tit 2.39 din 7.2%, thdnh phdn khodng vgt phd biin Id Thgch anh, Ulit vd Kaolinil, cd chica tdng mudi hda tan vai hdm lugng tit 0.35 din 3.62% vd nhiim phen vai pH = 5 6 din 7.0; Dung lugng trao ddi tit 3.6 den 15.6mg/100g ddt khd; vdi cation trao ddi dgc trung la ion Fe^^. Rieng ddt a Kien Giang la ddt than bun hda.cd ham lugng hihi ca la 44.28%. pH=4.}, trong thdnh phdn khodng vgt cd chua cdc khodng vdt khdc nhu Pyrit, Thgch cao vd Pyrophylnit. Kit qud thi nghiem cdi tgo ddt bdng xi mdng dia phuang vai hdm lugng tic 250 din 400kg/m^ a 91 ngdy tuoi cho thdy ddt set pha a An Giang cho
cttdng do khdng nen mot true (q,) la ldn nhdt trong khi do q,, ciia ddt than biin hda (TBH)a Kien Giang Id nhd nhdt.
Tic khoa: Ddt yeu, hieu ca, cdi tgo ddt, thdi gian bdo duang, cuang do khdng nen (q,).
Summary: Research results clayed soft soil distribution in the provinces of An Giang, Tien Giang, Hau Giang, Bac Lieu and Ca Mau and soil organic content from 3.16 to 7.2 %, the mineral composition is common quartz, illite and Kaolinite. containing total dissolved salt concentrations from 0.35 to 3.62 % and acidity with pH = 5.6 to 7.0; Exchange capacity from 3.6 to 15 6mg/100g dry soil; with cationic ion exchange is characterized Fe ^^. Kien Giang private soft soil is peat soil chemistry, organic content is 44.28 % , pH = 4.1, in the mineral
composition contains other minerals such as pyrite, gypsum and Pyrophylnit. Experimental results using soil reclamation local cement content from 250 to 400kg/m^ at 91 days of age showed in An Giang clay for uniaxial compressive strength (qj is the biggest, while (q„) of peat soil chemistry (TBH) in Kien Giang is the smallest,.
Keyword: Soft soil. Organic, Rienforced soil, curing time, unconfined (q,i).
I. DAT VAN DE (m). Phd bidn nhit la thanh tao ngudn gdc Tai Ddng bing sdng Cuu Long (DBSCL), ph6 '^"^ ^ ^'^"^ ^^^^ ^ chudng nim ngay trdn bign gap cac trim tich tre Holocen (Q) cd "^^h ^ ! ^ay tir 10 den > 20m; cac loai dat (am) nhigu ngudn gdc khac nhau nhu hSn hop sdng P^° ^'^"^ ^^ *"^ ^^t' ^^ ^^^ P^^> ^ ^ *^^t P*^^' - bign (am) hoac sdng - dim liy (ab), bign ^° " ^ ^^^^ ^^ ^^"l "^"°i' P^^"' ^ ^ ^^
ca,... Do v^y, cd thg xgp chiing vao nhdm ddt ' dac bigt. Vigc xay dung cac cdng trinh tai day Nguoi phan bijn: GSTS Tran Thj Thanh ^ L hit d6u phai thiit M giai phap xvr ly nSn.
Ngay nhan bai: 08/7/2014 .^ < , . . . , , " , . ; . ; ; . Ngay thong qua phan bi?n: 09/12/2014 ^rong so cac giai phap xu ly nen dat yeu da Ngay duy$t dang: 05/02/2015 ilipc ap dung trong hnh vuc xay dyng thiiy lgi
26 TAP CHl KHOA HOC VA CONG NGHE THUY LOI S(5 25 - 2015
"""*"'"• M-1-li'Hi'H!l-M
CO giai phap svt dung chSt kat dinh xi mang. C) mpt sa du an thupc DBSCL, phuang phap nay da mang lai hieu qua nhit dinh. Vin dS nghien cuu cac dac tinh xay dung cua dit va danh gia kha nang su dung cac Ioai xi mang dia phuong de xti Iy nen dit yiu trong xSy dvmg cac cong trinh thuy lpi cua dia phuong la cip thiet va rit CO y nghia thuc tS vh mat kinh tS.
PCB40; Tay Do PCB30 va Kien Luong' (Ha Tien 2) PCB40 voi cac ham lupng tir 250, 300, 350va400kg/m^
II. DAC DIEM PHAN BO VA TINH CHAT CO LY CUA DAT 6 MOT SO NOI THUQC DBSCL
2.1. Dac diem phan bo Bai bao hinh bay cac kSt qua da tiSn hanh
nghien cuu: mpt so dac h'nh xay dung cua dit nhu thanh phan khoang vat, hoa hpc, kha nang trao doi hap phu ciia dat loai set y8u tren phan bo tai cac tinh An Giang, Tiin Giang, Hau Giang, Kien Giang, Bac Lieu va Ca Mau; kha nang cai tao chung bang cac loai xi mang th6ng dung tai dia phuong nhu Tay Do
Bang 2.1: Dac diem phan bo cua dat yeu tai mot so vi tri nghien ciru
Tai mpt so khu vuc nghien ciru, da phan cac lop dat yeu phan bo ngay tren b6 mat dit tu nhien hoac phia duai voi dat dip va lop dit boi tich day tir l-2m. Chieu day cac lap dit yeu ttr 10 den tren 20m. Dac diSm phan b6 cua cac lop dat tai cac vi tri nghien ciiru so bp dupc trinh bay a bang 2.1.
^"""^-^^^^ Dja diem D$c diem phan ho~~~-~~^
Ldp dat tang phu
Cac lap dat yeu nghien ciiru
H. Cha Mcti- An Giang Set, xim nau.
deo cirng, day 2.7 dSn 3.4ni Set pha xen Icep
cat, deo chay.
day 7 den 1 Om Set, deo chay din chay, day 12den24.2in
H. Cai Lay- Tien Giang ' Dit ddp, day 1.2 den 1.5m
Bun set lin hflu CO, day 8.2 din
9.7m
G6 Quao- Kien Giang Dat dap, dtiy
0.8m
Bun set pha lln nhi6u huu ca, day 10 den
12.5m
TP.Vi Thanh- Hau Giang Dit dip, day 0.5
den 0.8m
Bun set, day 10 den 15m
H Dong Hai- B.Lieu Dat dip, day
1.5m
Bim set, day tir 8 den 12m
Set deo chay.
day 7.5 den 9.7m
H. Nam C5n- CaMau Dat dip, day
0.8-1.Om
BiJn set lln huu CO, day 2
den llm Bim set, day
tir 7.5 ^din 17m
2.2. Ket qua nghien ciiu cac dac tru-ng thanh phan vat chat, tinh chat co' ly cua dit 2.2.1. Kit qua thi nghiem thanh phin khoang vat cua dat
Cac mau dit duac tiin hanh thi nghiem xac dinh thanh phin khoang vat bing phuomg phap nhiet vi sai tren thiit hi may STA - PT 1600 va Ranghen nhieu xa (may D8 - Advance) tai Phong thi nghiem khoang vat Trung tam phan tich thi nghiem dia chit. Ket qua thi nghiem dupc trinh bay trong bang 2.2.
Tir kit qua nghien ciru thanh phan khoang vat chiing toi nhan thiy: Trong tat ca cac mlu dat
thi nghiem deu bat gap cac khoang vat co tinh phan tan cao nhu Hit, Monmorilonit voi ham lupng tir 14 den xap xi 24%; Su co mat cac khoang vat gcrtit, gipxit chirng to trong dit co chiia sat va nhom, phii hop voi diu hieu nhilm phen cua dit. Dp pH ciia dit thip, thuong la moi truang axit. Day la nhiing yiu ti gay bit lpi cho viec cai tao dat bang xi mang.
Nhu vay co the thiy ring: dat nghien ciiru la loai tram tich yeu, mai duac thanh t^o (do con tin tai cac khoang vat illit va monmorilonit), moi tnrong tram tich thuang co pH thip (do nhilm phen - sir c6 mat sit va nhom va co thi CO chua hihi co).
TAP CHl KHOA HOC VA CONG NGHE T H C I Y LOI S 6 25 - 2015 27
KHOA HOC
Bang 2.2: Thanh phan Idioang vat cua dat tji cac khu vurc nghien ciru
^~~~"^-^.^^ Dia diem
Ten dit
Monmorillonit Illit-KAl2[AlSi30io](OH)2 Kaolinit-A!2fSi30;](OH)4 Clorit - Mg2Ali[AlSi30iol(OH)8 Thgch anh - Si02 Felspat-KosNaojAISisOK Gcrtit - FejOj.HiO Pyrit - FeS;
Pyrophyllit-AirSi205T(OH) Thach cao - CaSO^
Khoang vat khac
H. Chg Moi - An Giang SPpha deo chay
it 14
B 7 47^9
4-6 3 it
Set deo chay
3-5 22-24 10-13 8 36-38
5-7 2-4
Pynt H.Cai Lsy - T.
Giang Biin set lln hilu CO
3-5 18-21 16-18 7 36-40
3-6 5 ,t
Pynt Go Quao
-K.
Giang B set pha lan nhiSu hihica
5 13 7 5 23-25
3-5 14-16
it 5-7 4 15 Gipxit,
TP.Vi ^ Thanh- H Giang
Biin set
2-4 19 16 8 39-11
4-6 7 it
Sident H. D6ng Hai - Bac Li6u Biin set
2-4 21-23 13-18 7-8 36-38
4-8 5-6 it
Can xit
H Nam c a n - CaMau Biin s6t lln hilu 2-4
22 21 8 30-32
6-8 5 it
Canxit Biins^t
4-6 20-24 19-21 7-8 29-33
4-7 5-7 il
Bom it, Canxit
2.2.2. Ket qua thi nghiem thanh phan hoa hpc cua dat
may quang pho phat xa Plasma IRIS INTREPID tai Phong thi nghiem Quang ph6 - Trung tam phan tich thi nghiSm dia chat. Ket qua thi nghiem dugc trinh bay tai bang 2.3.
Thi nghiem thanh phan hoa hoc cua cac mau d4t dugc thuc hien tren thiet bi ph5n tich la
Bang 2.3: Thanh phan hoa hgc cua dat tai cac khu vvc nghien cihi
^ ^ ^ Dia diem T P h 6 a h g c ( ? 5 ) \ Ten dat S1O2 TiOj AhOj FejO, FeO MnO CaO MgO K , 0 NajO P2O5 SO3 Hilu cor (450°C) MKN (900°C)
H. Cho Mai, An Giang S6t pha deo chay 68.44
0.80 1409 3.09 2.11 0.09 0.47 1.26 2.14 0.41 0.08 0.95 3.16 6.78
Set deo chay 59.54 0.87 18.76 3.49 2.34 0.10 0.47 1.62 2.73 0.46 0.11 1.13 4.60 9.04
H.Cai Ljy.T.
Giang BCmset 1^ hilu CO
57.18 0.93 17.6 4.89 2.55
•0.11 0.47 1.33 2.83 0.37 0.86 1.91 7.2 11.37
G6 Quao, Kidn Giang Bim set pha lln
nhieu hftu CO 27.87
0.37 9.23 6.67 0.15 0.12 1.30 1.38 1.75 0.27 0.11 10.80 44.28 50.05
TP.Vi Thanh, H.
Giang Bun sdt
59.93 1.08 17.52 3.90 1.65 0.16 0.77 1.92 2.96 0.77 0.20 1.20 2.39 8.00
H. D6ng Hai, Bac Ligu Biin six
59.65 0.90 16.78
5.12 1.74 0.12 0.93 1.74 2.57 1.05 1.11 0.53 4.43 9.23
H. Nam Can, Ca Mau Bun set lan
h&u CO 56.37
0.83 17.50 5.82 1.46 0.20 0.87 1.90 3.27 1.40 0.37 0.83 4.44 9.86
Bun set 57.60
0.81 16.92 4.24 1.52 0.10 1.72 2.35 3.02 1.51 0.24 1.72 3.17 9.50
28 TAP CHl KHOA H p C VA CONG NGHE T H O Y t O I 5(5 25 - 2015
I KHOA HOC l ^ E ! 3 ! B ! m
Ket qua phan tich thanh ph4n hoa hpc cua ddt cho thay:
- Cac 6k loai set a An Giang, Ti6n Giang, Hau Giang, Bac Lieu va Ca Mau co cac gia tri vh ham lugng cac 6 xit kha tuang d6ng: SiO; dao dong tu 56.37% d6n 68.44%; AI2O3 dao dgng tu 14.09 % dgn 18.76%; FeiOa dao dgng tir 3.09%
dSn 5.82%; FeO dao dgng tu 1.46% ddn 2.55%.
Rieng dat biin set pha lln nhiSu hmi ca a Kien Giang, ham lugng cac oxit tren lai ngugc lai cu the: SiOa - 27.87%, AI2O3 - 9.23%; FeO - 0.15%, Ti02 - 0.37%. Cac oxit nay dSu nho han trong khi do Fe203 - 6.67% va SO3 - 10.8% 1^
Ion hon. Tong ham lugng cua cac 6 xit mu6i de hoa tan (NaiO va K2O) dao dgng tir 2.02% d§n 4.67% trong do ddt a Ca Mau diu >4.5%. Cac
kSt qua tren chting to dat co dki hi6u ciia nhilm phen va muoi d6 hoa tan, rieng dit h&u ca a Kien Giang co tinh phen manh.
Ve thanh phan vat chat hiiu ca cho thay: hau hdt cac dat nghien cuu a tren la loai dat lan hiiu ca (ham lugng hmi ca <10%), Rieng dat a Kien Giang co ham lugng hiJu ca kha cao (44.23%) la loai d4t than bim hoa [1].
2.2.3. Ket qua thi nghiem kha nang trao doi cua dat
Ket qua phan tich kha nang trao ddi ciia ddt dugc thuc hien tai Phong phan tich hoa moi truang - Vien Nirac, Tuoi tieu va Moi truang.
Moi Ioai dat dugc thi nghiem 6 mau, k^t qua thi nghiem dugc trinh bay a bang 2.4.
Bang 2.4: Kha nang trao doi cation ciia dat
^"•""---^^^ Dia diem Chi tieu ^ " - ^ - ^ ^
pH TSMT Fe'*
Fe'*
Ca'*
Mg'*
Al'*
Cl- SO,'- Na*
K*
CEC TongN Mun Mn
Dcfn vj
%
mg/lOOg mg/IOOg Idl/lOOg Idl/lOOg Idl/lOOg mg/lOOg mg/lOOg Idl/lOOg Idl/lOOg mg/lOOg
%
%
mg/kg
H. Cho Moi, An Giang
S^t pha deo chay
5.8 0.3459 207.18 16.26 6.04 4.02 0.10 13.47 188.52 1.67 0.30 6.08 0.064
1.98 7.82
Sii deo chay 5.7 0.5245 1733.06 55.26
5.36 7.45 0.12 68.06 78.36 2.12 0.78 8.84 0.84 2.10 1204.0
H. Cai Liiy, T.
Giang B. set lan hihi CO
5 6 0.5431 589.76 12.79 7.70 6.61 0.07 15.07 75.37 1.33 0.30 3 60 0.11 2.33 661.0
Go Quao, K. Giang B.set pha lan nhigu hitu CO
4.1 0.75821
153.50 6.00 1.02 1.09 1.00 25.26 308.20
0.68 0.47 15.60 0.33 19.41 2558.3
TP.Vi Thanh, H.Giang Bun set
62 2.298 331.50 9.50 6.80 11.80
0.0 464.4 168.37 15.22 1.08 15.00 0.081 2.97 1213.8
H. Dong Hal, Bgc Litu Bun sat
6.3 3.6240 3 2 4 2 5 18.75 7.0 10.60
0 0 857.89 131.63 17.74 1.40 6.60 0.14 2.76 663.5
H. Nam Can, Ca Mau B. s^t lin
hihj CO 7.0 1.73731
72.0 8.0 0.48 2.33 0.0 522.0 42.88 9.70 1.17 17.98 0.22 13.90 33.0
Biln set 6.7 2.19436
184.67 13.56 0.54 1.64 0.0 934.74
16.65 16 19
1.06 8.51 0.11 3.49 612.87 Kit qua phan tfch kha nang trao doi cation cua 15.6mg/100g dat kho (dit a Kien Giang, Hau ddt cho thay: Giang va bim set lln hiiu co 6 Ca Mau); cac - Dung luong trao d6i cua d a dao dpng tu 3.60 f ° " f ^^''° """« I'"?nB '^ao d6i tir 6.08 mg /lOOg dat kho (dit a Tito Giang) iin <len8-84mg/100g.
TAP CHl KHOA HOC VA CONG NGHE T H O Y L I J I 5(5 25 - 2015 29
I KHOA HOC M B g 3 ! B ! l ^
Thanh phto cation trao doi; cation Fe * chiim uu thi; ik a Hau Giang, Bac Lieu ya Ca Mau c6 chira anion Cl' (tir 464.4 dto 934.74mg/100g dk kho) IcJn hem nhito so voi dat a An Giang, Tito Giang va Kien Giang (chi ti: 13.47 dto 68.06mg/100g dit kho). Tuy nhito dfa a Ca Mau lai co lugng anion SO4 - nho hon dat 6 cac noi khac.
- T6ng mu6i hoa tan (TMHT) cho thdy; Dfa a Hau Giang, Bac Lito va Ca Mau co TMHT kha Ion tir 1737.31 dto 3624.0 mg/lOOg dfa kho trong khi d6 dfa tai cae noi eon lai dao dong tir 345.9 dto 758.21 mg/lOOg dfa kho.
- Dp pH eija dfa trong viing nghito cuu eho thjy dfa eo dp pH thSp thucmg nho hon 7 thupc moi tnrong axit.
- Theo phto loai vi dp man dua vao ty le ham lupng anion CV (%o) c6 trong dfa [2] cho thSy: Dfa 6 Ca Mau, Bac Lito tir man nhito dto rfa man (Cr>5); dfa a Hau Giang - man it (Cr = 1.5 - 3.0); Tien giang, An Giang va Kito Giang la khong inan Cr < 1.5.
Theo phto loai cua eac tac gia V.M. Bezruk, Bang 2.5: Dac tinh ctf ly cua dat
Yu.L. Motulev, A.L.Grot, A.I.Znamenxki, M.F. leruxalimyxkaya [1] dira vao dang nhiem mu6i xac dinh theo ty le anion Cr/S04 eho thiy dfa tai Ca Mau va Bac Lito thi dfa bi nhiem mu6i Cloma (Cl-/S04^- >2); Dfa tai Hau Giang nhiem muoi Clorua- Sunfat (Cl /SO4
=1.466); Dfa tai Kito Giang, Tito Giang va set tai An Giang nhiem muoi dang Sunfat - Clorua.
Cilng theo cac tac gia trto thi di dtoh gia phto loai theo mire dp nhilm muoi dua theo tong luong muoi tnmg binh eae muoi de hoa tan, tinh theo % kh6i lugng dat kho eho thay dfa tai Ca Mau, Bac Lito va Hau Giang a mirc nhilm mu6i; Dfa a Tito Giang, An Giang va Kito Giang a mirc nhiem muoi it.
2.2.4. Kit qua thi nghiem cac chi tito co ly hito truang va trong phong
Tai cae vi tri nghito euu, dto tien htoh cac thi nghiem tai hien truong nhu eat canh va thi xuyto tito chuto; cac thi nghiem trong phong dupc tito htoh vol eac chi tito co ly thong thuong. Ket quii duge trinh bay t^i btog 2.5.
Ioai set yeu tai cac vi tri nghien ciru
Chi tieu
D i a aiem
Ten dat
•1
1
Chi tieu vat ly
- N h o m hat cat (%) - N h o m hat hui (%) - N h o m h3t set {%) D o am t ^ nhien (%) Khoi luong ths tich t u nhien y^ {t/m') K M h i o n g l h e i j i i k h J x r t
Kh6ilupngtiengys(tta^
D o ban h i a G (%) D o rong n (%) H? so rong Eo
H. Cho M f t - A n Giang Set pha, deo chay 61.1 22.5 16.4 39.5
1.76
1.26 2.67 94.0 52.9 1.122
Set, deo chay 43.6 21.1 3 4 . 3 50.7
1.68
1.12 2.67 97.2 58.2 1.392
H.Cai Lay - T. Giang B. set lan hihi CO 35.5 24.0 40.5 66.5
1.57
0.94 2.59 98.5 63.6 1.745
Go Quao - K.Giang Bselpltilln nhiiu hiiu CO
66.5 153 18.3 285 1.13
0 2 9 1.90 9 8 . 6 84.6 5.492
T P V i Thanh- H.Giang BQnsSt
33.9 19.3 4 6 . 7 93.5 1.48
0.76 2 . 6 7 99.9 71.5 2.502
H, Dong Hai- Bac Lieu Biin set
31.1 2 7 . 8 41.1 5 8 . 6
1.62
1.02 2 . 6 7 97.1 6 1 . 7 4 1.614
H. Nam Can- C i Mau
B.set lln hihi CO
38.5 23.0 38.4 83.9
1.49
081 2.61 9 8 . 2 6 9 . 0 2 . 2 2 6
Biln set
37.0 20.4 42.6 76.6
1.54
0.87 2,65 9 9 . 3 67.2 2.046
30 TAP CHl KHOA HOC VA CONG NGHE THUY LOI Sl3 25 - 2015
KHUAHUC ^ • . I t l J I c l J M ! ! ^
^ ^ ^ - ^ ^ Dja diem Chi tieu ^ " ^ ^ ^ ^ Tan dat
a i
a1 i
<
o
u TNcit cinhh
iii^i han chay WT (%) ji6i han deo Wp (%) Chi s6 deo Wn (%) Do set B Goc ma sdt trong (p (do) Luc dinh C (kPa) H^ s6 n^n lun ai.2 (cm'/kG) Su (kPa) Su' (kPa) Mo dun biin dang Eo (kPa) SUc chiu tai quy uoc, Ro (kPa) H? s6 thdm, K (cm/s) Thinghi?mSPT,Njo
H. Cho l^di - An Giang set pha, deo chay 41.3 27.7 13.6 0.86 6°33' 6.96 0.096 20.10 4.12 2647.8
53.0 2.61x10-'
2 Set, deo
chay 49.8 30.5 19.4 1.05 4°19' 5.59 0.217 21.57 3.53 1284.7
42.2 1.7x10-'
2 H.CaiUy -T. Giang B. Ut \h hsuco
62.0 34.6 27.5 1.16 . 3°32'
3.73 0368 17.36 3.92 676.7 32.4 5 21x10^
2 GO Quao •
K.Giang BsilthLlIn nhidibQuco 235.8 171.6 64.2 1.77 2°04' 1.47 1.649 lOlO 3.24 490.3 17.7 1.28x10-*
1 TP.Vj Thanh- H.Giang Biin set 71.6 38.0 33.6 1.65 2"14' 2.06 0.771 14.32 3.33 735.5 23.5 Z-llxlO-*
1-2 H. Dong Hai- Bac Ueu Biln set
57.1 33.3 23,8 1.06 3°07' 3.33 0.465 15.30 3.53 725.7 31.4 2.2x10-'
1-2
H Nam can- Ca Mau B^tlan
hiiu CO 76.2 43.1 33.1 1.23 2°28' 2.75 0.577 14.81 451 5884 26.5 16x10'
1 Biin set
69.6 38.0 31.7 1.22 3"22' 402 0.427 15 89 4,90 666.8 32.4 5 Id xto*
1-2
K6t qua thi nghiem cac chi tieu ca ly ctia dat tai cac vung nghien cuu cho thay dat nghien cuu d^u la nhung lop dat yeu (set, set pha trang thai deo chay din chay, bun set, bun set pha Iin huu ca). Dit co tinh chdt xky dung kem, he s6 nen liin lan, sue chiu tai nho, he s6 rong lan...., cac loai dlt nay khi xay dung cac cong trinh deu phai c6 cac bien phap cai tao chung hoac giai phap mong thich hop.
Tir dac tinh ca ly cua dAt cho thay: dat tai vung An Giang co kha nang cai tao bang xi mang tot han vi khu vuc nay dlt co ham lugng hat set nho va hat cat cao hon ddng thai dat bi nhilm rau6i it; con dlt tai Kien Giang co kha nang cai tao bang xi mang cho hieu qua thip vi trong dk CO chiia nhiiu hmi ca, moi trucmg axit lan han cac dlt or noi khac.
m NGHIEN C i m CAI TAO DAT YEU TAI DBSCL BANG XI MANG DIA PHlTONG Nh4m danh gia kha nang cai tao dat yeu tai cac vi tri nghien cijru tren bang xi mang dia phuang (Tay Do PCB340 - TD30, Tay Do PCB40 -TD40 va Kien Luang PCB40 -KL40),
chiing toi da tien hanh nghien cuu cac mlu dat nguyen trang va che bi voi cac ham lugng xi mang khac nhau la 250, 300, 350 va 400 kg/m"'. Dlt a day dugc lua chgn nghien cuu va so sanh gom:
Set pha trang thai deo chay den chay a An Giang;
Set trang thai deo chay den chay a An Giang;
Bun set pha lan nhieu huu ca (than bun hoa) 6 Kien Giang;
Biin set a Hau Giang;
Biin set a Ca Mau.
Mau dugc che bi theo phuong phap trgn kho TCVN 9403-2012 [3] ngoai ra co tham khao tieu chuin JGS 0821-2000 cua Nhat Ban [5]
va tieu chuan DBJ08-40-94 cua Trung Quoc [4], Tuy nhien, de co ket qua nghien cuu sat voi thuc te nham ap dung cho phuang phap khoan phut cao ap, a day chiing toi lua chgn ty le nuac/xi (W/C =1). Mau dugc bao duang trong dieu kien bao hoa a cac ngay tuoi 7, 14, 28, 56, 91 va 180 sau do dugc thi nghiem nen mot true khong han che na hong tren thiet bi
TAP CH[ KHOA HOC VA C O N G N G H £ T H O Y L O I S 6 25 • 2015 31
KHOA HOC
may nen ba true. Tieu cliuAn thi ngliiem ap dunglaASTMD2166.
3.1. Thanh phin hoa hpc cua cac loai xi mang nghien clhi
Bi danh gia anh huong cia xi mang dia chat
luong dit gia c5, chiing toi da tiSn hanh nghien cuu thanh phto hoa hoc cua cac xi ming thong dung CO tren dia ban la Tay Do PCB30 (TD30); Tay Do PCB40 (TD40) va Kien Luang PCB40 (KL40). KSt qua thi nghiem duoc neu trong bang 3.1.
Bang 3.1: Kit qua thi nghiem xac dinh thanh phin hoa hpc cua cac loai xi mang
\ L o a i XM
SiOj Ti02 AI2O3 FezOj FeO M n O CaO M g O
TD30
25.41 0.66
•6.20 3.91 1.01 0.06 49.42
2.53 TD40
21.71 0.46 5.27 3.43 0.56 0.07 54.74
2.91 KL40
16.97 0.26 4.70 3.23 0.12 0.05 60.42
1.81
" ^ ^ Loiii XM
T P H H ( % ) ^ \ K2O NazO
P2O5 SO3 CT2O, Finess MKN(900°C)
TD30
1.25 1.24 0.20 1.93 0.010
0.95 6.29
TD40
1.23 0.79 0.15 2.25 0.01 0.83 6.85
KL40
0.89 0.26 0.11 1.40 0.006 1.65 9.63
Til k a qua nghien ctiu ham luong cac 6 xit CO trong 3 loai xi mang nghien ciiu cho thiy: Cac oxit Si02, Ti02, AI2O3, Fe203, FeO cua xi mang TD30 dSu cao hon xi mang TD40 va KL40 con oxit CaO lai nho hon, t6ng lugng oxit kijm (Na20 va K2O) cua xi mang TD30 cung Ion hon xi mang TD40 va KL40.
3.2. Kit quanghiencmidiit^odatbangxi mang 3.2.1. KSt qua thi nghiem cua cac mlu o 91 ngay tuoi.
K6t qua thi nghiem xac dinh cuong do khang nen mpt true khong han che no hong ciia cac mau d4t o 91 ngay tuoi, cai tao voi cac loai xi mang tren dupc trinh bay tai bang 3.2.
Bang 3.2: Ket
H.lu?ng(kg/m')
" ^ - ^ U o j i X M Loai dat ^ ^ ^ \ ^
set pha deo chiy . An Giana Sdt dio cMy - An Giang sit tiHu CO- Kien Giang Biin set-Hau Giang Bun sel - Ca Mau
qua thi nghiem mau nen ft 91 ngay tuoi (qu- 250
TD30
975.2 934.7 68,4 583.1 817.1
TB40
939.1 885.3 148.3 721.0 624.8
KL40
1012.4 649.1
82 7 954,3 812.3
300
TD30
1108.5 1057.4 116.7 684.5 857.1
TB40
1123.8 1000.3 164.8 7474 721.4
KL40
1032.1 886.3 1274 972.9 867.9
350
TD30
1470.0 1137.6 119.8 884 3 867.5
TD40
1250.9 1202.0 169.9 789 7 828.5
KUO
1282.2 10815 145.9 1020.6 937,3
kPa) 400
TD30
1625,9 11834 210,6 982.6 1227.3
TD40
1569.0 1220.2 201.0 8724 1191.2
KL40
1435.2 12772 ISS.8 1248.1 12273
Bieu d6 quan he tuong quan giira cuong dp khang nen mpt true (qu) voi cac loai dSt, ham lupng xi mang o 91ngay tuoi dupc the hien 6 hinh 3.1 den hinh 3.3.
32 TAP CHl KHOA H p C VA CONG NGHE THLIY LOI SO 25 - 2015
KHOA HOC r M . ; . i ; ! c l ! M ! l : ^
Hinh 3.1. Bieu do quan he gida qu vdi ddt gia Hinh 3.2. Bieu dd quan he gida qu vai ddt gia CO bdng xi mdng Tdy Dd PCB30 theo hdm cd bang xi mdng Tdy Dd PCB40 theo hdm
lugng a 91 ngdy tudi lugng a 91 ngdy tuoi
Hinh 3.3. Bieu do quan he gOca qu vai ddt gia cd bang xi mdng Kien Luang PCB30 theo hdm
lugng a 91 ngdy tudi
Tir k^t qua thi nghiem cuang do khang nen mgt true cua d^t gia c6 tir cac loai xi mang tren voi cac dk loai set khac nhau chiing toi co mgt s6 nhan xet nhu sau:
CJ moi loai dit, khi ham lugng xi mang gia c6 cang cao thi cuang do khang nen mgt true cua ddt gia co cang cao (bang 3.2).
Voi d4t set pha, set a An Giang su dung xi mang TD30 d l gia c6 cho kat qua vd cuang do khang nen mgt true qu la cao hon so voi su dung xi mang TD40 va KL40. Dilu nay co the ly giai la do trong thanh phSn hoa hgc cua xi mang TD30 co chiia nhiSu 6 xit silic (SiOa) han va lugng oxit canxi (CaO) it han so vai xi mang TD40 va KL40 (Bang 2.3 va 3.1)
Vai dat bim set a Hau Giang va Ca Mau thi viec gia c6 bang xi mSng KL40 hieu qua han so vai xi mang TD30 va TD40, nguyen nhan
CO the la do trong thanh phan hoa hgc cua xi mang KL40 co lugng oxit Canxi (CaO 60.42%) lan han so v6i xi mang TD30 (49.42%) va TD40 (54.74%).
Dat set pha lan nhieu huu ca (TBH) a Kien Giang cho gia tri cucmg do khang nen rat nho so vai dat nghien cuu 6 nai khac. Tuy nhien gia CO bang xi mang TD40 cho ket qua khang nen lan han so vai xi mang TD30 va KL40.
Dat biin set 6 Hau Giang gia co vai xi mang TD30 ham lugng 250 kg/m^ thi cuang do khang nen nho han nhieu, chi bang 36.2 den 80.9% so voi xi mang TD40 va KL40 a cimg ngay tuoi.
3.2.2. K6t qua thi nghiem nen mau bao duong theo thai gian
Voi cac ham lugng gia co cua moi loai dat va xi mang, chiing toi deu tien hanh bao duong va thi nghiem a cac ngay tuoi la 7, 14, 28, 56, 91 va 180. Ket qua thi nghiem cho thay: Vai dat a An Giang, Hau Giang, Bac Lieu va Ca Mau thi cuang do khang nen mgt true tang ty le thuan theo thai gian bao duang. Con dat bim set pha lan nhieu hihi ca (TBH) a Kien Giang thi cuong do mau tang tu khi che bi den 14, 28 va 56 ngay tuoi con khi Ion hon 56 ngay tuoi, cuang do mau lai giam. Ket qua nay phu hgp voi ket qua nghien cuu cua cac tac gia tai [6], [7], [8] va [9] va dugc giai thich la do trong
TAP CHlKHOA HOC VA C O N G N G H E T H O Y LOl S<5 25 - 2015 33
KHUAHUC M l III III III M
d4t CO ham lupng axit humic tang cao va trong 3.5 va 3.6 bi8u thi quan he giiia cuong dp thanh phSn cua dat c6 chiia cac khoang vat khang nen mpt true theo thoi gian cua dat gia Thach cao va Pyrit va PyrophiUit. Hinh 3.4, c6 voi ham luong 300kg/m'.
Hinh 3.4. Bieu do quan he giUa qu v&i ddt vd Hinh 3.5. Bieu do quan he giUa qu v&i ddt vd xi mdng Tdy Do PCB30 hdm luang 300 kg/m' xi mdng Tdy Bo PCB40 hdm luang 300 kg/m'
theo thdi gian theo thai gian
Hinh 3.6. Bieu do quan he giira qu vai ddt vd xi mdng Kien Luang PCB40 hdm luang 300
kg/m theo th&i gian
IV. KET LU^N
1. Dat loai set ySu (am) phan b6 tai cac tinh An Giang, Tiin Giang, Hau Giang, Kien Giang, Bac Lieu va Ca Mau bi nhilm mu6i de hoa tan, co chiia hiru co, ton tai chii ylu trong m6i truong co dp pH thdp, thuang <7. Bdt tai An Giang, Ttin Giang it chua, khong mSn va nhilm muoi Sunfat - Clorua; ddt tai Hau Giang it chua, man it va nhilm mu6i Clorua - sunfat; ddt t^i va Bac Lieu, Ca Mau thu^c dlt man nhieu va nhilm mu6i Clorua; ddt tai Kien Giang la chua manh, khong man, nhiem mu6i d^g Sunfat - Clorua.
2. Dat gia co bang xi mang cho thay; ddt tai An Giang voi xi mang TD30 cho hieu qua hon xi miing TD40 va KL40 con dat 6 Hau Giang va Ca Mau thi gia co bang xi mang KL40 hieu qua hon TD30 va TD40.
3. D6 dat cucmg dp q„ >800 kPa thi ddt ct Hju Giang va Ca Mau phai gia co voi ham lupng la
>350kg/m' doi voi ca 3 loai xi mang tren trong khi do ciing cuong dp nay thi ddt a An Giang chi cdn ham lupng la 300 kg/m' voi ddt set va
>250kg/m' voi ddt set pha.
4. Dat bun set pha ldn nhiSu huu co (than biin hoa) o Kien Giang thi cai tao ddt bdng xi mang se khong hieu qua, cuong dp khang nen mpt true cua dat la rat nho so voi cac Ioai ddt set vo CO khac.
5. Qua trinh bao duong mau va thi nghifm theo thai gian cho thiy cuang dp khang nen cua cac mdu ddt loai set khong lan hoac lan it hint ca , vcii thoi gian bao duong cang lau thi gia tri (qj cang tang con d6i voi ddt hilu co thi (qu) ban dau tang sau do (qu) suy giam. Vdn de nay can duoc nghien ciiu sau hon nhdm cai tao loai dat nay.
34 TAP CHl KHOA HOC VA CONG NGHJ T H C I Y LOI SO 25 - 2015
I KHUA HUC [ M J . I J I J j y ! l ^ TAI HEU THAM KHAO
[1] Do Minh Toan (2013), Dit da xay dung va phuang phap cai tao. NXB Xay dung, Ha Ngi [2] D6 Dinh Sam, Ngo Dinh Qui, Nguyin Tu Siem, Nguyen Ngoc Binh (2006), Cdm Nang
nganh Lam Nghiep, Ddt va dmh duang dit. Bg Nong nghiep & PTNT .
[3] TCVN 9403-2012. Gia c6 nkn dk yh bang tru dit xi mSng. NXB Xay drag, HaNgi.
[4] DBJ08-40-94 - Quy pham ky thuat xir ly nen mong (ban dich). Tieu chuan TP Thugng Hai, Trung Qu6c.
[5] JGS 0821-2000 - Japanese Geotechnical Society Standard "Practice for Making and Curing Stabilized Soil Specimens Without Compaction"
[6] N. Z. Mohd Yunus, D. Wanatowski va L. R. Stace," Lime Stabilisation of Organic Clay and the Effects of Humic Acid Content" Geotechnical Engineering Joumal of the SEAGS &
AGSSEA Vol.44 No.l March 2013 ISN 0046 - 5828.
[7] W. Zhu, C. F. Chiu, C. L. Zhang, and K. L. Zeng, (2009) "Effect of humic acid on the behaviour of solidified dredged material," Can. Geot. J., vol. 46, no. 9, pp. 1093-1099,2009.
[8] S. Koslanant, K. Onitsuka, and T. Negami, (2006), "Influence of salt additive in lime stabilization of organic clay," Geot. Eng. J., vol. 37, pp. 95-101,2006.
[9] P. Harris, O. Harvey, S. Sebesta, S. R. Chikyala, A. Puppala, and S.Saride, "Mitigating the effects of organics in stabilized soil," TechnicalReport No. 0-5540-1, Texas Transportation Institute, USA, 2009.
TAP CHf KHOA HOC VA C O N G N G H E T H O Y LOI S(5 25 - 2015 35
