THIET KE MONG COC

VATLIEUTCVN 5574/1991Mac BetongRn(KG/cm2)Rk(KG/cm2)AoaoEb(KG/cm2)Loai thepRa(KG/cm2)Ra(KG/cm2)Ea(KG/cm2)Gii han chay(KG/cm2)1506560.4280.62210,000AI210016802,100,0002400200907.50.4280.62240,000AII280022402,100,00030002501108.80.4120.58265,000AIII360028802,100,0004000300130100.4120.58290,000CI200016002,100,0002000350155110.3990.55310,000CII260020802,100,0002600400170120.3990.55330,000CIII340027202,000,000340050021513.50.3850.52360,000CIV500040002,000,000500060025014.50.3650.48380,000

TINH LUN MONG COC BTCTTNH TOAN O LUN CHO MONG COC BTCT.TEN MONG:M1Mo hnh tnh toan o lun la na khong gian bien dang tuyen tnh vi han che quy c nen co chieu day t emong en o sau tai o ng suat gay lun bang 20% ng suat do trong lng ban than at gay ra.Cong thc tnh o lunng suat gay lun tai trong tam e mong :Trong o :s tctb =35.76(T/m2)higi =25.7(T/m2)Bmq =2.37(m) - Be rong mong khoi quy c.Lmq =2.37(m) - Chieu dai mong khoi quy c.gmq =0.876(T/m3) -Dung trong at ay mong khoi quy c.(co ke en ay noi khi lp at nam di mc nc ngam)Vays glz =0 =10.01(T/m2)Chia chieu day lp at thanh cac lp co chieu day hi = Bmq/5 =0.47(m)BANG TNH NG SUAT DO TRONG LNG BAN THAN VA TAI TRONG NGOAIs i gl = Ko x sz =0 gl(T/m2)s i bt = g z +higi(T/m2)IEMz(m)Lmq/Bmq2*z/BmqKos i gls i bts i bt /s i gl00.001.0001.00010.025.72.610.471.000.40.9609.626.22.720.951.000.80.8008.026.63.331.421.001.20.6066.127.04.441.891.001.60.4494.527.46.1Vung hoat ong nen lun cua at nen lay en o sau z = 4.45m so vi e mong .BANG TNH O LUNLP AThi(cm)s btP1is gls tb glP2ie1ie2iSi(cm)1472.5752.5951.0010.9813.5760.5800.5700.302.6160.9612472.6162.6370.9610.8813.5180.5770.5690.242.6570.8013472.6572.6780.8010.7043.3820.5760.5690.212.6990.6074472.6992.7200.6070.5283.2480.0000.0000.002.7400.449TONG O LUN S (cm)0.75Ghi chu:1. Cac gia tr ng suat trong bang tnh o lun co n v tnh ( KG/cm2)2. Cac cong thc tnh :Ket luan :Ta co S < Sgh = 8cm, do o thoa man yeu cau bien dang

Fa- DAI MONG COC BTCTTNH KET CAU AI COCTEN MONG:M1ng knh coc d =0.25(m)Vat lieu ai coc :+ Be tong mac :200, Rn =90(KG/cm2)+ Thep :CII, Ra =2600(KG/cm2)Kch thc mong:+ Canh dai :2.2(m)+ Canh ngan:2.2(m)Kch thc co cot:+ Canh dai :0.8(m)+ Canh ngan:0.8(m)I. CHON O CAO AI COC h :h =1(m)Ta co thap xuyen thung bao trum cac au coc nen kha nang xuyen thung khong co.II. BANG TNH LC TAC DUNG LEN AU COC Q :Tong so x2i y2iV tr cocNttMttxMttyQGhi chucoc n(m2)(m2)xd(m)yn(m)(T)(T.m)(T.m)(T)81.281.280.750.7579.72.83330.9Coc bien81.281.28-0.75-0.7579.72.833-11.0Coc bien81.281.280.750.979.72.83331.381.281.28-0.750.979.72.833-7.4III. TNH COT THEP AI COC Fa :1. S o tnh :Xem ai coc la ban consol ngam tai mep cot con au t do tai mep mong.2. Tai tac dung:La phan lc cac au coc3.Bang tnh toan :(Vi ho = h -15cm)Xet mat ngamM(T.m)Fa (cm2)Chon thepFa (cm2)a (mm)theo phngS.thanh.knh(chon)Canh ngan37.118.7181636.2120Canh dai37.118.7181636.2120.Yeu cau ky thuat :1.au coc ngam vao ai coc toi thieu 15cm.ho = h -15cm

&LT&"VNI-Times,Normal"NH TOAN MONG COC BE TONG COT THEP&L&"VNI-Times,Normal"THIET KE : KS. NGUYEN TRAN KHOA

KT THEP TRONG COC BTCTKIEM TRA COT THEP DOC TRONG COC BTCT KHI VAN CHUYEN VA LAP DNGCac thong so ve coc:+ Chieu dai oan coc L=10(m)+ Canh coc d=25(cm)+ Be tong coc mac :300, Rn =130(KG/cm2)+ Thep coc :CII, Ra =2600(KG/cm2)+ S.thanh thep 1 canh coc :2+ .knh thep doc trong coc :16I. KHI VAN CHUYEN COC:1. S o tnh :dam n gian, goi ta tai v tr moc cau khi van chuyen. V tr moc cau cach moi au coc 1 oan0.207L (L: chieu dai oan coc), nham tao momen goi va momen nhp bang nhau2. Tai trong q(T/m) :la trong lng ban than coc ke them he so ong khi van chuyen la 1.5q = 1.5 (d/100)2 gbt =0.234375(T/m)3. Momen M(T.m) :M =0.502(T.m)4. Dien tch cot thep can thiet Fa(cm2) :Fa = M / 0.9*Ra*ho =1.073(cm2)5. Ket luan :am bao an toan khi van chuyenII. KHI LAP DNG COC:1. S o tnh :dam n gian, goi ta tai v tr moc cau khi lap dng va v tr dng coc. V tr moc cau cach aucoc 1 oan 0.297L (L: chieu dai oan coc), nham tao momen goi va momen nhp bang nhau2. Tai trong q(T/m) :la trong lng ban than coc ke them he so ong khi van chuyen la 1.5q = 1.5 (d/100)2 gbt =0.234375(T/m)3. Momen M(T.m) :M =1.034(T.m)4. Dien tch cot thep can thiet Fa(cm2) :Fa = M / 0.9*Ra*ho =2.209(cm2)5. Ket luan :am bao an toan khi lap dng

&L&"VNI-Times,Normal"THIET KE:KS.NGUYEN TRAN KHOA

MONG COC BTCTTNH TOAN MONG COCTEN MONG :M1Yeu cau ve cach bo tr coc :I.- XAC NH S BO KCH THC AI COC- Khoang cach gia cac truc coc ln hn hoac toi thieu bang 3 lan canh coc d.- Lc doc tnh toan tai co mong Ntto =70(T)- oi vi mong nha khoang cach t mep ai en truc hang coc bien : d- Sc chu tai cua coc c chon e tnh mong Qc =50.6(T)- Dung trong trung bnh at va be tong mong gtb =2(T/m3)- o sau chon mong Df =1.1(m)- Tong chieu dai coc Lp =4(m)- Canh coc d =25(cm)- Khoang cach cac coc bo tr trong ai la 3d =0.8(m)- Ap lc dnh gia nh do phan lc au coc gay ra:Ptt = Qc / ( 3d)2 =89.9(T/m2)- Dien tch s bo ai coc :F = Ntto /(Ptt -1.1g tb Df)=0.8(m2)- Trong lng cua ai va at tren ai :N = 1.1F Df gtb =1.9(T)- Lc doc tnh toan tai cao trnh ay ai Ntt :Ntt = Ntto + N =71.9(T)II.- XAC NH SO LNG COC nc & BO TR HE COC TRONG AI.nc = 1.2*Ntt /Qc =1.7(coc)- So coc chon:8(coc)- nhx=3(So hang coc theo phng x)- nhy=3(So hang coc theo phng y)- L =2.0(m - Canh dai cua ai mong)- B =2.0(m - Canh ngan cua ai mong)- Dien tch thc cua ai sau khi bo tr he coc (m2):F =4- Trong lng cua ai va at tren ai :Nt = 1.1F Df gtb =9.7(T)- Lc doc tnh toan tai cao trnh ay ai Ntt :Ntt = Ntto + Nt =79.7(T)- Momen tnh toan tai tam ay ai Mtt :Mtt y=33.0(Tm)Mtt x=2.8(Tm)III.- KIEM TRA TAI TRONG TAC DUNG LEN COCLc truyen xuong 1 coc hang bien:Qttmax= Ntt /nc + Mtty* xmaxnen/ x2i+ Mttx* ymaxnen/ y2iQttmin= Ntt /nc - Mtty* xmaxnen/ x2i- Mttx* ymaxnen/ y2iTrong o :xmaxnen =0.75(m) - khoang cach t tam hang coc chu nen ln nhat theo phng x en tam aiymaxnen =0.75(m) - khoang cach t tam hang coc chu nen ln nhat theo phng y en tam ai x2i=1.28(m) - Tong bnh phng khoang cach theo phng x t tam cac hang coc en tam ai y2i=1.28(m) - Tong bnh phng khoang cach theo phng y t tam cac hang coc en tam aiVayQttmax=30.94(T)Qttmin =-11.02(T)Ta co :Qttmax > Qc .Nen dieu kien kiem tra khong thoa manIII.- KIEM TRA ON NH NEN DI MONG KHOI QUY C.Bang tnh goc ma sat trong trung bnh.Lp athi (m)j (o)hi * jjtb (o)2817.27138.16017.63218.8437.680008.5890.0000027.9910.000Tong10175.840Ghi chu:hi : chieu day cua lp at th i tnh t ay ai mong.Goc truyen lc :a = jtb /4 =4.4(o)Chieu dai ay mong khoi quy cLmq = (L - d) + 2Lp tga =2.37(m)( Canh dai mong L:2.0(m) )Chieu rong ay mong khoi quy cBmq = (B - d) + 2Lp tga =2.37(m)( Canh ngan mong B:2(m) )Dien tch ay mong khoi quy c :Fmq =5.59(m2)Xac nh trong lng mong khoi quy c:Lp athi (m)g (T/m3)hi gT.lng lp i ( T)132633.6281.96715.73680.2322.0054.0120.4000.86200.0000.87600.0Tong25.7134.1Ghi chu:lp at th 1 tnh t ay ai mong tr len va dung trong la dung trong trung bnh gia at va be tongla 2 T/m3.Trong lng ban than he coc:Nc =5(T)Trong lng mong khoi quy c :Nmq =139.1(T)Lc doc tieu chuan tam ay mong khoi quy c:Ntcmq =200(T)Momen tieu chuan tam ay mong khoi quy c:Mtcmq = Mtco + Qtco (cao trnh ay MKQ -cao trnh nh ai)Mtcmq =169(T.m)o lech tam tieu chuane =0.84(m)Ap lc tieu chuan ay mong khoi quy c:smax =112.40(T/m2)smax =-40.89(T/m2)stb =35.76(T/m2)Cng o tieu chuan cua at nen di mong khoi quy c :Trong o :m1 =1.3m2 =1.1ktc =1(V cac ac trng lay t phong th nghiem)jtc=jmq=18.840A, B, D : cac he so phu thuoc jtcA =0.465B =2.861D =5.454Be rong mong khoi quy c :Bmq =2.37(m)Dung trong at ay mong khoi quy cgmq =0.876(T/m3)(hi x g i) =25.7(T/m3)c mq =0.283(T/m2)Rtc =108.92(T/m2)Ket luan :Khong thoa man

&L&"VNI-Times,Normal"THIET KE:KS. NGUYEN TRAN KHOA

CHIA LOPCHIA LP AT COC L36,D35,H3TEN LPSTTHi (m)Zi(m)LP 1110.5222324426528`621072128214921610218110.319.15LP 2121.42013221.7141.123.25LP 3151.424.5161.626171.827.718229.619231.6201.133.15LP 4210.634221.735.15CHIA LP AT COC L49,D40,H3TEN LPSTTHi (m)Zi(m)LP 1110.5222324426528621072128214921610218110.319.15LP 211.4202221.731.123.25LP 311.424.521.62631.827.74229.65231.661.133.15LP 410.834.12235.53237.54239.55241.56243.57245.580.446.7LP 510.146.952248CHIA LP AT COC L21,D25,H3TEN LPSTTHi (m)Zi(m)LP 1110.5222324426528621072128214921610218110.319.15LP 211.720.15

SUC CHIU TAI COC BTCTXAC NH SC CHU TAI CUA COC BE TONG COT THEP.TEN MONG:M1I.- SC CHU TAI CUA COC THEO VAT LIEUTrong o:Mac beton200Rn=90(KG/cm2)Loai thepCIIRa=2600(KG/cm2)m =0.7(he so ke en anh hng uon doc coc)d=25(cm) - Canh coc.L=4(m) - Chieu dai coc.S.thanh thep:4.knh thep:14Aa=6.157(cm2)Vay :QVL =50.6(T)II.- SC CHU TAI CUA COC THEO CH TIEU C LY CUA AT NEN(Tieu chuan XDVN 205:1998)Sc chu tai cho phep cua coc n xac nh theo cong thc:Trong o:QTC :Sc chu tai tieu chuan tnh toan theo at nen cua coc n.KTC :He so an toan ke en anh hng cua nhom coc(Ktc = 1.4 - 1.75), s bo ta chon:KTC =1.65m=1(He so lam viec cua coc trong at )+ Xac nh sc chong mui coc Qp:mR=1(H.so lam viec cua at mui coc co ke en anh hng p.phap ha coc,tra bang A3 )qp (T/m2): Cng o chu tai cua at nen mui coc , tra bang A1 phu thuoc o sau mui coc va trang thai at mui coc.qp=615(T/m2)Vay sc chong mui coc:Qp=38.4(T)+ Xac nh thanh phan ma sat hong Qf:Trong o:+ u: chu vi mat cat ngang coc,(m)u=1.0(m)mR=1(H.so lam viec cua at mat ben coc co ke en anh hng p.phap ha coc,tra bang A3 )fsi : ma sat ben coc, tra bang A2 phu thuoc o sau trung bnh cua lp at, trang thai at.(T/m2)li : chieu day lp at th i ma coc i qua.(m)BANG NOI SUY TUYEN TNH.LP ATli (m)Zi (m)Bfsi (T/m2)fsi liThong so 1Giatr thso 1Thong so 2Giatr thso 2Thong so trung gianGiatr thso trung gian10.000.000.170.0000.01010501511707978.000.000.000.170.0000.0154002045019440.000.000.000.170.0000.0152902032020320.000.000.000.170.0000.00.90.310.21.26-0.060.000.000.170.0000.00.90.610.51.070.4322.001.000.153.5007.0104.6155.118.655.472.003.000.154.8009.6309.33510258.602.005.000.155.60011.2309.33510258.602.007.000.156.00012.0309.33510258.6032.009.000.146.35012.7106.5157.2157.200.0010.000.140.0000.00.0010.000.140.0000.0(Ghi chu : thong so 1 < thong so 2)TONGD roi52.5Vay thanh phan ma sat hong Qf:Qf=52.5(T)Do o:QTC=90.9(T)Ket luan : sc chu tai cua coc xac nh theo ch tieu c ly cua at nenQa=55.1(T)III.- SC CHU TAI CUA COC THEO CNG O CUA AT NEN(Tieu chuan XDVN 205:1998)Sc chu tai cho phep cua coc tnh theo cong thc:+ Xac nh sc chong mui coc Qp:Trong o:qp (T/m2): Cng o chu tai cua at nen mui coc tnh theo cong thc sau:V o sau chon mong cua mong coc rat ln so vi canh coc d nen thanh phan th 3 kha be so vi 2 thanh phancon lai ta bo qua.Do o Cng o chu tai cua at nen di mui coc xac nh theo cong thc:Vi :c =0.17(T/m2) - Lc dnh cua at mui coc.j=26.9(o) - Goc ma sat trong cua at mui coc.j=0.469(rad)Nq =15.7Nc =29.0s'vp : ng suat co hieu theo phng thang ng tai o sau mui coc do trong lng ban than at, (T/m2)Lp athi (m)g (T/m3)hi g11.52320.51.7440.87232.21.4963.291241.50.8621.293519.20.87616.8192Tong25.3Ghi chu:Lp at th 1 tnh t ay ai mong tr len va dung trong la dung trong trung bnh gia at va be tongla 2 T/m3.Vay cng o chu tai cua at nen mui coc:qp =402.4(T/m2)Do o sc chong mui la:Qp =25.1(T)+ Xac nh thanh phan ma sat hong Qf:Trong o:+ u: chu vi mat cat ngang coc,(m)u=1(m)fsi (T/m2) - ma sat ben tac dung len coc xac nh theo cong thc:Vi :ca =c(T/m2) - Lc dnh gia than coc va at.ja=j=(o) - Goc ma sat trong gia coc va at nen.s'h (T/m2) - ng suat hu hieu trong at theo phng vuong goc vi mat ben coc.li - chieu day lp at th i ma coc i qua.(m)LP ATZtb (m)c(T/m2)j(o)g (T/m3)li (m)gh (T/m2)Kss'h (T/m2)fsi (T/m2)fsi liGhi chu21.850.24913.7631.7250.53.1910.7622.4320.8450.4MNN nam gia lp 3,33.201.84015.0561.9892.25.8100.7404.3012.9976.61.989 la dung trong t nhien45.050.5306.8540.9141.57.5840.8816.6791.3332.0515.400.17026.9000.86719.216.5930.5489.0854.78091.8TONG100.8Ghi chu:Ztb: o sau trung bnh cua lp at.Vay thanh phan ma sat hong Qf:Qf=100.8(T)Vay sc chu tai cua coc xac nh theo cng o cua at nenQa=58.8(T)Ket luan : Sc chiu tai cua coc chon e tnh toan mong :Qchon=50.6(T)GHI CHU:1. - Ket qua tnh toan sc chu tai cua coc theo cng o cua at nen ch ap dung cho nen at la"at dnh".2. - oi vi "at ri", cng o chu tai di mui coc va ma sat ben tac dung len coc nhng o sau lon hn osau gii han Zc(m),th c lay bang gia tr tng ng o sau gii han.Ngha la:fs (Z>Zc) = fs ( Z= Zc)qp (Z>Zc) = qp (Z=Zc)o sau gii han Zc(m) xac nh theo goc ma sat trong cua at nen.(hnh B4-tuyen tap TCXDVN -trang436)3. - Bo qua lp at san lap day 2m va lay o lam cao o mat at t nhien.4. - Coc ong sauD roi(m)- t cao 0.00m o gia nh.(Nam di cao o khao sat a chat 2m).

&L&"VNI-Times,Normal"KS.NGUYEN TRAN KHOA

COCCHIUTAINGANGSC CHU TAI NGANG CUA COC - TCXDVN 205-1998.1-Cac thong so ve coc:+ Loai coc :V( V - coc vuong ; T- coc tron)+ Chieu dai coc L =24(m).+ Canh coc d =0.3(m).+ Mac beton:300+ Eb =290000(KG/cm2).+ Rn =130(KG/cm2).+ Loai thep:AII+ Ea =2100000(KG/cm2).+ Ra =2800(KG/cm2).2- Tai trong :+ Momen M =17.5(T.m)+ Lc ngang H =9.52(T)3- Tnh toan:Momen tnh toan tiet dien ngang cua coc:I =0.000675(m4)o cng tiet dien ngang cua coc:EbI =1957.5(T.m2)Chieu rong quy c cua coc:bc =0.950(m)He so ty le K -tra bang G1 tuyen tap TCXDVN :205-1998.K =500(T/m4)He so bien dang:abd =0.753(m-1)Chieu dai tnh oi cua coc trong at:Lc =18.080(m)Cac he so khong th nguyen tra bang G2 -tuyen tap TCXDVN:205-1998.Ao =2.441Bo =1.621Co =1.751Cac chuyen v ngang tai cao trnh mat at do ng lc n v at tai cao trnh nay.dHH =0.00292(m/T)dMH = dHM =0.00146(T-1)dMM =0.00119(m-1T-1)Chuyen v ngang tai cao trnh mat at .yo =0.0533(m)Goc xoay tai cao trnh mat at .Yo =0.0347(rad)Ghi chu:yo ,Yo :chuyen v ngang (m), va goc xoay (rad) cua tiet dien ngang coc mat at vi coc ai cao mc ay ai vi coc ai thap.lo =1.5- Chieu dai oan coc (m), tnh t ay ai en mat at.Chuyen v ngang tai cao trnh ay ai.Dn =0.1208(m)Goc xoay tai cao trnh ay ai.Y =0.0536(rad)BANG TNH AP LC TNH TOAN sz (T/m2),MOMEN Mz (T.m), LC CAT Qz (T).o sau zzeA1B1C1D1sz(m)(m)(T/m2)00.10.20.30.40.50.60.70.80.911.11.21.31.41.51.61.71.81.922.22.42.62.833.54

PHU LUC MONG COCTHAM KHAO TIEU CHUAN XAY DNG VIET NAM 205-1998BANG A1 - Sc chong cua at mui coc qp (T/m2).o sau cuaSc chong cua coc ong va coc ong khong nhoi be tong ,qp (T/m2)mui coc(m)Cua at cat chat vaSoiTho-Tho vaMnBui-Cua at set vi ch so o set IL bang00.10.20.30.40.50.63750660/400300310/200200/120110604830680/510380320/250210/160125705880700/620400340/280220/200130807970730/690430370/330240/22014085101050770/730500400/350260/24015090151170820/750560440/400290165100201260850620480/4503201801102513409006805203501951203014209507406503802101303515001000800600410225140BANG A2 - Ma sat ben fs (T/m2).o sauMa sat ben coc fs (T/m2)trung bnhCua at cat chat vacua lp atTho & tho vaMnBui------(m)Cua at set vi ch so o set IL bang0.20.30.40.50.60.70.80.9113.52.31.51.20.50.40.40.30.224.232.11.71.20.70.50.40.434.83.52.521.10.80.70.60.545.33.82.72.21.60.90.80.70.555.642.92.41.710.80.70.665.84.23.12.51.810.80.70.686.24.43.32.61.910.80.70.6106.54.63.42.71.910.80.70.6157.25.13.82.821.10.80.70.6207.95.64.1321.20.80.70.6258.66.14.43.221.20.80.70.6309.36.64.73.42.11.20.90.80.73510753.62.21.30.90.80.7BANG A3 - Cac he so mR,mf .Phng phap ha cocHe so ieu kien lam viec cua at c ke en 1 cachoc lap vi nhau khi tnh toan sc chu tai cua coc.Di mui coc mR mat ben coc mf1. Ha coc ac va coc rong co bt mui coc, bang bua hi (treo), bua may va bua diezel112. Ha coc bang cach ong vao lo khoan moi vi o sau mui coc khong nho hn 1m di ayho khoan,khi knh lo khoan moi:a) Bang canh coc vuong10.5b) Nho hn canh canh coc vuong 5cm.10.6b) Nho hn canh canh coc vuong hay knh coc tron (oi vi tru ng day tai ien) 15cm.113. Ha coc co xoi nc trong at cat vi ieu kien ong tiep coc met cuoi cung khong co10.9xoi nc4.Rung va ep coc vao :a) at cat chat va:- Cat tho va tho va1.21- Cat mn1.11- Cat bui11b) at set co o set IL =0.5- A cat0.90.9- A set0.80.9- Set0.70.9c) at set co o set IL < = 0115. Ha coc rong h mui bang bua co ket cau bat ky.a) Khi ng knh lo rong cua coc 40cm0.716. Coc tron rong , bt mui, ha bang phng phap bat ky, ti o sau ln hn 10m, sau o com rong mui coc bang cach no mn trong at cat chat va va trong at set co o set ILIL >0 xac nh bang cach noi suy.BANG A5 - He so mf .Loai coc vaphng phap thi cong cocHe so ieu kien lam viec mf cua at trongCatA catA setSet1)Coc che tao bang bien phap ong ong thep co bt kn mui roi rut dan ong thep khi o BT0.80.80.80.72)Coc nhoi rung ep0.90.90.90.93)Coc khoan nhoi trong o ke ca m rong ay, o be tong :a)Khi khong co nc trong lo khoan(phng phap kho) hoac khi dung ong chong.0.70.70.70.6b)Dc nc hoac dung dch set.0.60.60.60.6c)Hon hp be tong cng o vao coc co am( phng phap kho)0.80.80.80.74)Coc ong ha bang rung co lay at ra10.90.70.65)Coc - tru0.70.70.70.66)Coc khoan nhoi coc co lo tron rong gia, khong co nc trong lo khoan bang cach dungloi rung.0.80.80.80.77)Coc khoan phun che tao co ong chong hoac bm hon hp be tong vi ap lc 2-4 atm0.90.80.80.8BANG A6 - He so trong cong thc A.8; A.9Cac he soGoc ma sat trong tnh toan cua at jI (o)232527293133353739Aok9.512.617.324.434.648.671.3108163Bok18.624.832.845.56487.612718526040.780.790.80.820.840.850.850.860.87a50.750.760.770.790.810.820.830.840.85Khi L/dp=7.50.680.70.70.740.760.780.80.820.84100.620.650.670.70.730.750.770.790.8112.50.580.640.630.670.70.730.750.770.8150.550.580.610.650.680.710.730.760.7917.50.510.550.580.620.660.690.720.750.78200.490.530.570.610.650.680.720.750.7822.50.460.510.550.60.640.670.710.740.77>=250.440.490.540.590.630.670.70.740.77b