Tap chiKHKTMo Bia chat, sd30, 4/2010, tr 24 28 NGHIEN CUtJ SlTC KHANG CAT CO K E T THOAT N U O C TREN THIET BI CAT PHANG NGUYEN THI NU, Trudng Dgi hgc Mo Dia chdt Tdm tat Bdi bdo trinh bdy kit qud xdc[.]
Tap chiKHKTMo - Bia chat, sd30, 4/2010, tr.24-28 NGHIEN CUtJ SlTC KHANG CAT CO K E T - THOAT TREN THIET BI CAT PHANG NUOC NGUYEN THI NU, Trudng Dgi hgc Mo - Dia chdt Tdm tat: Bdi bdo trinh bdy kit qud xdc dinh sire khdng cdt ciia ddt bdng thiit hi cat phdng theo so thi nghiim cd kit - thodt nude Thi nghiim time hiin theo lieu chudn ASTM D30S0 vd BS 13~":1990 Kit qua nghiin cini ddi vdi mot so logi ddt tgi khu viiv Hai Phdng Trd Vinh vd Sdc Trdng cho thdy thdi gian cd kit trirdc vd timg logi ddt: ddt trgng thdi nua cirng- deo eihig tir I din gid: Ugng thdi deo mim tir din gid: trgng thdi deo chay -elm' tir din gid tdc cat khoang 0.12mm phiit Gid tri sire khdng cdt hiru hiiu: set gey CL Uxing thdi chcy: c '=0.053kG''em': (p '=2fl8': set gdy CL trgng thdi deo chay: c '=0.058kG/enf: rp '=23"42': set bio CH, trgng thdi deo ehcy: e'=0.059kG/cm-: (p'=2f38': set gca' CL Ugng thdi deo mem: c'=0,076kG/cm-:(p'=25"38'; sit heo CH trgng thai deo mini: e'=0.0''8kG'eni': (p'=24'\S9': Sit gdy CL trgng thdi deo eimg:e'=0.08^kG/cin-: (p'=2d'0': set gdy CL trgng thdi nua cimg: e'=0.130kG/enr: (p'=28"42' xac djnh thai gian cd ket, tdc cat da dinh trudc Dat van de ma} cat irng bien cd dii chain de thi nghiem Hien nay, thiet bi cat phang dugc sir dung cat chain - cd ket la bet sire can thiet rdng rai tren the gidi va d Viet Nam Theo tieu Quy trinh thi nghiem xac dinh sue khang chuIn Viet N a m ^ C V N 4199-1995), xac dinh cat cd ket -thoat nude theo tieu chuan ASTM SU'C khang cat cua dat bang thiet bi cat phang 3080 va BS 1377:1990 - Part dugc thuc hien theo ba so dd khac nhau: cat De tien hanh xac dinh sire khang cat, thdng nhanh - khdng cd kef cat nhanh - cd ket hoac cat thudng chuan bi ba mau dat tir mot mau nguyen chain - cd ket Cac tieu chuan My (ASTM dang de thi nghiem cat dudi ba cap ap lire nen D3080) va Anh (BS 1377:1990) di cSp thiit bi khac Gia tri cac cap ap luc nen thang cat phang chi su dung de thi nghiem theo so dd dung lira chgn thudc vao trang thai ciia dat cat chain - cd ket nham xac dinh cac thdng sd Thi nghiem dugc tien hanh theo hai bude: khang cat huu hieu ciia dat Phan Idn cac cdng 2.1 Cd kit mdu trinh cd vdn dau tu nude ngoai, theo yeu cau ciia Tac dung ap luc nen thang dirng len mau chu diiu tu viec xac dinh sue khang cat thudng thi Theo ddi va dgc bien dang nen tren ddng hd nghiem dieu kien cd ket -thoat nude theo bien dang ke tii' tang tai tai cac thdi diem cac tieu chuan nude ngoai Mau dat thi nghiem khac de lap thj quan he giua bien dang dugc cd ket trirdc dudi ap luc nen thang du'ng cho thang du'ng (s) va thdi gian (t), s = f( VT) hoac den ket thiic giai doan cd ket tham, sau mdi s = f(lgt) Thi nghiem cd ket dugc tien hanh tiep tien hiinh cat vdi tdc du chain de khdng cd su tuc cho den qua trinh cd ket tham ket thiic bien ddi ap lire nude Id rdng cat Sd lieu thi nghiem cho phep thu dugc cac thdng sd sire 2.2 Cdt mdu khang cat huu hieu (c" cp") cua dat Tuy nhien Trudc tien hanh cat mau can xac dinh tdc cac tieu chuan ASTM D3080 va BS cat Tdc cat dugc xac djnh dua vao thdi 1377:1990 khdng dua cu the thdi gian nen cd gian pha buy mau tdi thieu va bien dang cat Then ket mau dat Mat khac tac dung lire cat, tdc gian pha hiiy tdi thieu dugc tinh tii' tso theo dd thi cat phai du chain de dam biio su bien ddi ap lire s = f(lgt) hoac t9o va tiootheo dd thi s = f( VT )• nude Id rdng cat ga} la khdng dang ke Hau * Theo tieu chuan BS 1377: 1990 [ I ] sir dung het cac phdng thi nghiem o' Viet Nam hien thi S = f( VT ) keo dai doan gan nhu tuyen tinh md} cat phang irng bien thudng mua d Trung CLia dd thi (thudng nam khoang thdi gian tii' Quoc loai hai hoac ba tdc cat nen khdng the din 50% cua cd ket tham) xudng dudi: xac djnh dieu chinh dugc tdc cat theo dung cac tieu diim giao giua dirdng vdi dudng nam ngang chuan nude ngoai na} Do vay, viec nghien ciru qua diem cudi tren dd thi cd ket thlm, gia trj dd la 24 ti.,1, tren true f\ Xac dinh thdi gian pha hu} tdi thieu t, (thdi gian huy ddng sue khang clt den cue dai cua mau) theo cdng thuc: t, = 12.7.t|oo Udc tinh biin dang cat nam ngang (df) cua mau tai thdi diem pha buy (mm) Tdc cat drdugc tinh theo cdng thuc: d, = — (mm/phiit) * Theo tieu chuIn ASTM D3080 [3] thdi gian tir luc bat dau cat den pha huy mau (t,-) dugc xac dinh theo cdng thirc :tr = 50.t5o dd tjo la thai gian de dat cd ket tham 50% Gia trj tso xac djnh true tiep tir thj s = lg(t) hoac dua vao thi s = f(V^) tinh dugc tyo (thdi gian de dat cd ket tham 90%) vii xac dinh tso theo cdng thirc:, - '"" 4.28 Tdc cat dr dugc tinh theo cdng thirc: d = -J^ (mm/phiit) t|- T'rong qua trinh thi nghiem cat, ddng thdi ghi cac chi sd ciia thiet bj luc ddng hd dich chuyen ngang ddng hd bien dang thang dirng va thdi gian cat Tii' bat dau thi nghiem den mau bi pha huy cat thi phai dgc dugc it nhat la 20 gia tri Khi mau gan bi cat sd lan dgc phai tang len nham xac djnh chinh xac thdi diem mau dat bj cat Sau mau bj cat xong can xac am ciia dat Ket qua thi nghiem xac lap dugc dd thi quan he giua irng suat cat x va ap lire nen a (T = f(a)) til' dd ,\ac djnh gia trj luc dinh ket bieu kien C" va gdc ma sat huu hieu cp' ciia dat Noi dung va ket qua nghien ciiu siic khang cat cd ket - thoat nude ciia dat 3.1 Lira chgn logi ddt nghien ciru Mau dat dugc lay tai khu vuc Hai Phdng Trii Vinh va Sdc Trang cd phan va trang thiii khac chii yeu la dat set set pha (CH CL) trang thai tir nira cirng, deo cirng, deo mem deo chay den cha}' Mail dat dugc thi nghiem xac dinh cac chi tieu \i"il 1} \'a phln hat Thi nghiem phan tich thiinh phln hat theo tieu chuan ASTM D420 xac djnh gidi ban cha} vii gidi han deo theo ASTM D4318 Goi ten dlt theo tieu chuan ASTM 0248"^ .vac djnh trang thai cua dat theo thi nghiem SPT Ket qua phan tich cho tha} dat chu }eu la CL (set gay), CH (set beo) Ngoai cdn I mau MH (bui dan hdi) (bang 1) Can cu' vao ti'ang thai, sd lugng mau nghien cuu sii'c khang cat nhu sau: Dat CL, trang thai chay: mau: Dlt CL, CH, MH, trang thai deo chay: 20 mlu: Dat CL, CH, trang thai deo mem: 23 mau: Dat CL, trang thai deo cirng: 15inau: Dat CL, trang thai nua cung: 7mau 3.2 Nghien ciru xdc dinh sire khdng cdt cd kit - thodt nude cua ddt Thi nghiem dugc tien hanh tren thiet bi may cat phang iing bien cua Trung Qude loai tdc Mau dat dugc cd ket trudc, thi nghiem dirng nhan thay qua trinh cd ket tham ket thuc Ve dd thj quan he giua kin va fi {s = i{f\)) Tren thj cd the nhan biet mau dat da ket thiic cd ket tham hay chua Theo ket qua nghien ciru thdi gian cd ket tham phu thudc vao tirng loai dat cu the nhu sau: Dat CL, trang thai chay: den gid; Dlt CL, CH, MH, trang thai deo chay: den gid: Dat CL CH, trang thai deo mem: den gid; Dat CL, trang thai deo cii'ng: den gid; Dat CL, trang thai nira ciing: I den gid Sau cac mau cd ket xong tien hanh cat mau vdi tdc chain nhat tren may cat phang irng bien Thdi gian cat thuc te (thdi gian pha hiiy tdi thieu mau) gan gidng vdi thai gian cat tinh toan theo ly thuyet (bang I) Tdc cat thuc te mau dat tinh toan khoang 0.12mm/phut Thdi gian cat thay ddi khoang 80 phiit den 190 phiit thudc vao loai dat Nhu vay, tdc cat cham nhat tren may irng bien tuong ddi phii hgp vd'i tdc cat tinh toan ly thuyet Ket qua xac dinh sue khang cat cua dat tren may cat phang iing bien cho gia tri d bang Ket qua thi nghiem dugc tac gia so sanh vdi ket quii nghien ciru cua mdt sd tac gia Bowles, Ladd et al (1977), Bjerrum and Simons (1960) Kanja and Wolle (1977), Olsen et al.(1986) [3.4.5] va gia tri sire khang cat cd ket - 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