KHOA HOC & CONG NGHE
Khai thae cac thong tin thu duorc tCrthf nghiem cat CT^^
trong xOr ly nen dat yeu cr Viet Nam
Exploiting information from the vane shear test in soft ground treatment in Vietnam
Chu Tuan Vu
Tom tat Thi nghiem cat canh trong dai yeu co rat nhilu Uu diem nhung van chUa dUdc iii dung rong rai 6 Viet Nam. Viec sul dung ket qua thi nghiem cat canh, hien mdi chi Aiinq il sdc khang cat T va do nhay S^, hieu qua chua cao.
Vi vay de khai thacva suTdung hieu qua cac thong tin thu dutfc tif thi nghiem cat canh,
bai bao hifdng tcri gi^i quyet van de.
- Xay dung moi quan he tuong quan giila sii'c khang c^t cua dat xac djnh bang thi nghiem cat canh vdi lu'c dinh ket cua dat xac dinh bang th) nghiem trong phong.
Titkhoa: Thinghiem cot canh
Abstract Vane lest is useful but the results of such methods
have not been widely publicized in Viet Nam.
Because the applications are not so good, nowadays just have only shear strength and sensitivity of soil.
For exploit the effective application informations from vane test, the paper show problem, - Establish Ihe correlative relation of shear strength from vane test and stid<iness of soil indicate by
laboratory test Key words: Vane test
ThS. Chu Tudn Vu
Bo mon Dia ky ihiidl, Khoa Xdy dimg DT: 0963672525
Emaihchutuanvu34@gmail com
Ngay nhan bai Ngay Slla bai:
Ngay duyet dang
1. Tong quan
Trong ITnh vuc dja ky thual hien nay cd r i i nhieu phuang phap xac dinh sue chdng elt ciia d i t nhu. Cac phuang phap thi nghiem trong phdng bao gdm thi nghiem e l l phang, thi nghiem nen ba tryc, Ihi nghiem nen mdl Iruc Cac phuang phap ihi nghiem ngoai Irdi nhu nen sap, nen d l y ngang... Day la nhirng phuang phap Iruyin Ihdng da dugc sir dung rdng rai d Viet Nam va duae xay dung thanh nhtfng quy Irinh, quy pham hoan ehinh Tuy nhien nhtPng phuang phap nay eung bdc Id nhu'ng ban ehi do vide lly mau, van ehuyin miu va gia cdng mau ggp khd khan ddi vdi thi nghiem trong phdng Hoae thudng ddi hdi kinh phi Idn dli vdi thi nghiem ngoai trdi.
Thi nghiem o i l canh cd nhtrng uu diim gon nhu: van hanh dan gian, k l l qua thi nghiem khach quan phan anh dung Irang thai t i n lai eua d i t Nhung cac kit qua dd chi ia nhu'ng thdng lin v i sire khang cat a trang thai nguydn dang Sf^max va trang thai pha hiiy Si^min eiing vdi dd nhay S,. NhO'ng so lieu nay hien van chua duae su dung mdt each chinh thing nhu cac gia tn t^, C Irong thiit k l nln mdng. Do vay, thi nghiem e l l eanh ehua dugc sir dung rgng rai d Viet Nam, vm dae thCi eae thanh phi ldn va cae khu edng nghiep hlu h l l nam tren nln d i t yeu.
Cau hdi duge dai ra: lam t h i nao d i khai Ihac va sir dyng cae thdng lin thu duac Itr Ihi nghiem eai canh mdl each hieu qua.
2. HUo'ng giai quyet van de
De giai quyit vin d i da neu d tren, trude h i i cln de cap tai quan niem v i c^e dgc trung sire khang cit ciia dat va lir dd xay dung cac mdi quan he luang quan gitra sire khang e l l xac djnh bing cac phuang phap Iruyin thing va itr ihi nghiem e l l canh,
1. SLK khang cit cua dit
- Sire khang c i t x eiia dit la mdl dac trung ca hpc eua dat, nd ching nh&ng phy thudc vao ban chit eiia loai dit ma cdn duac quyit dmh bdi trang thai ton lai eiia nd bao gdm chidu sau va phuang e l l eho dti gia thiit d i t ding nhit, dang huang,.,
- cp, C va T quan he vdi nhau theo dinh nghTa sau:
T = a Igcp + C 6" day o la ap luc phap tuyln
Nhu vay cae Ihdng so (p, C dugc xac djnh bdi sue khang c i l T va a thdng qua he phuang trinh i, = a, Igcp + C,
Thi nghiem e l l eanh chi xac dinh duac T khdng cho bill dLcp'e gia trj a tuang ung vi t h i khdng lim duge gia tri ctia cp va C.
2. Xay difng cac mdi quan he tuvng quan gi(ya Sf^ max va C
Tren ca sd c^c kit qua thi nghiem e l l eanh hien truang cung voi cac k i t qua thi nghiem e l l phang trong phdng tuang irng dugc thue hien tren cac m l u dat tai cae vimg Ha Ndi, ven bien Thanh Hda - Vinh, viing duyen h^,i """hflnh p h i H i Chi IVlinh vdl so luang gan 1000 mlu da rijt ra duac mdt s i q^j , ,,|^u, „ „ „ .
+ Tai ciing mpt mlu thi nghiem, cac gia In Sft,min thu duoc o nhunq lan elt lien lilp la khdng thay doi. V i hien tugng nay cd t h i giai thich p.hw sau
- Mat e l l khdng thay doi d eae i l n e l l k l ca lan e l l d trang inai nguygn dana - Sau lin elt nguyen dang, cac lin e l l sau duac tidn hanh IB. mat c i l d i t d "
bi pha hiiy cac mdi hen kit, Tuy nhien can phai ndi ring theo thoi gon va tirna loai d i l ma kha nang phye hdi cae m i l lien k i l cd t h i xay ra 6 c c mirc do kh nhau.
7 2 TAP CHi KHOA HOC KIEN TRUC - XAY DUNG
Tir nhung nhan djnh dd cd the di den gia thuyet Sf„min = p N tg cp
Trong dd N la lue phap tuydn tren mat e l l
p la mgt hang so phy thudc vao kha nang phuc hoi cac mil lien k i t kiln trtie, linh chit biin dang cua mat c i t do cac lap chit gay ra sau i l n cat nguyen dang,
+ Trong cting mot loai d i l lue dinh k l l C la gia Irj khdng Ihay d i l Iheo chilu sau cdn sire khang e l l Sf^ max la gia Iri tang theo chieu sau vi vay khdng the xay dung quan he luang quan bac nhit tuyin tinh mdl ehilu eho Ige dinh k l l C va sire khang e l l Sfv max. Glai phap eho v i n d i nay la dua vao ddng thai 2 thing sd Sf^, max va Sfv min theo hUo'ng dd giua eae thdng so ciia thi nghiem elt canh va luc dinh k i t xac djnh bang Ihi nghiem e l l phang trong phdng cd quan he tuang quan long quat nhu sau:
S(vmax - Sf^min = aC + a
Dllu nay phii hgp vdl gia thuyit Sf^min = |3 N Igcp So vdi cac quan he ma cac tac gia khac da thiit lap thi trong quan he nay C chang nhung phu thudc vao Sf„ max ma cdn phy thude vac S|v min. Trgng cdng thirc tren a la mdt hing sd phu thupe vao mirc dp ddng nhlt.
Nlu dat ding nhit a = 0
Niu d i t khdng ding nhat a>0. Doi vo'i d i t set hoae btin set pha lan vd sd vting Thanh Hda - Vinh a = 0,05 - 0,15KG/
cm^,
a la he s i phy thupe vao su phan loai d i t Do eae tai lieu de xac djnh ve luoi va ngudn gdc viing ven biln Thanh Hda - Vinh va vfjng duyen hai thanh phd Ho Chi IVIinh chua d i y du ndn d nhtVng vting nay khdng chia ra thanh cac tuoi nguin goe khae nhau ma budc d i u chia ra lam 7 loai dat cd eae he s6 a nhu sau:
STT
1 2 3 4 5 6 7
Daf bun set, bun set pha
T i n g Ttiai Binh alV3 tb Tang Hai Hu'ng T i n g Vinh Phuc VCing Thanh Hoa . Vinh Vting duyen hai thanh ph6 H6 Chi Mmh Dk huu CCf tang Hai Hung Bat bun set, set pha l i n vo so vung Thanh Hoa - Vinh
a
1,0.1,2 0,8-1,1 0,7 - 0,9 0,9-1,3 1,0-1.6 0,4-1.7
a (KG/cm^)
0 0 0 0 0 0 0,05-0,15 3. Ket luan
1. Thi nghiem cat canh eho phep nhan duac Igc dinh k i t C thdng qua quan he luang quan Sf^,max - Sf^min = aC + a.
2. Ngoai viec xac dinh C dua vao quan he tuang quan c l n luu y ring nhiiu lae gia da lap dugc nhu'ng quan he gitra S^, max vdi ehi so qua ed k i t ORG, vai md dun long biin dang E, hoae tai Hdi nghj ca hgc d i t va n i n mdng hgp 6' Riodejanero thang 8 nam 1989 dua ra mdi quan he giii'a sue khang cat T xac djnh bing thi nghiem e l l eanh hien truo'ng d irng suit truac co k i t
Pc = aF„. Su Fv{KPa}
Xong l i t ea nhii'ng k i t qua iren v i n ehua duge Ihir nghiem Iren n l n d i l y l u d Viet Nam.
Nhu vay blng nhieu nghidn ciru tilp theo thi nghiem cat canh chang nhO'ng giiip linh loan sire ehiu tai dat nen ma edn cung e l p nhtrng thdng sd iien quan d i n x.ir ly va cai lao n i n d i t y l u nhu xae dmh duac mddun long biln dang eua dai, ung suat truoc co ket /
Tai lieu t h a m khao
I. Tsytovich NA Soil Mechanics. 4thed. Moscow StroiizdatI959 1961 Z Cue Bia chat Vi$t Nam - Tdi lieu khdo sat thanh Idp ban do dm chdt ty le 1/50 000
(tiep theo trang 71)
Tai lieu t h a m khao
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