Cd t h i Qng dung trong tfnh todn sO bp ode kfch thude cpc, sd cpc trong ndn mdng coc theo phuong tidn tfnh thu cdng hoac ldp trinh theo phuong phdp sd gidi bdng mdy vi tfnh.[r]
(1)DIIN DAN KHOA HOC C6NG NGHE
A i T R O N G THANG DUlNG T R O N G N E N M O N G C Q C
D O A N D J N H T H O A - T r u n g T a m G r o u p f o r m L KHAI QUAT
odi vdi n i n mdng cpc, tfnh toan thilt k l va lua chpn cac dae trung co ban cua cpc vd ddi cpc, de don gian va thuc hdnh thuan tien, ngudi ta thudng phai bo qua nhQng y l u td dnh hudng luc nho hon nhieu so vdi nhQng y l u td can ban vd dnh hudng luc Idn rd ret hon Trong thuc t l vide tfnh todn ban d i u trudc h i t chi xet cac tai trpng thdng dQng vd cdc phan luc ngupe can bing Thudng chi xdt trpng lupng ban than ket c l u , de mong hay dai cpc, cdc trang thiet bi k i t c l u , tac dpng trpng tdi cua ngudi sQ dung tren cong trinh theo djnh mQc ky thuat quy dinh Cdc phan luc thudng cd phan luc tai d i u mui cpc, luc ma sdt giQa than cpc va d i t n i n , dp luc day ngupe cua nudc n g i m d i t n i n bdo hda nudc tdc dpng vdo cdng trinh Cdc tai trpng khong thudng xuyen nhu gid bao, cdc dpng luc khdc , thudng dung d l tfnh todn k i l m tra khd nang chju luc hoac chdng b i l n dang vd hieu chinh kfch thude coc Cd t h i bd qua khong xdt d i n n l u cdng trinh nho hoac tam thdi Mpt each tdng qudt, phuong trinh can b i n g luc mo td su tuong tac luc theo nhdm cdc y l u td dnh hudng gdm nhdm luc chu dpng va nhdm phdn luc cua cdc dai lupng vat ly b i l u thj cdc y l u td anh hudng nhu vdy
J L PHUONG TRINH CAN BANG LUC TRONG NEN iUIONG CQC
1 Phirong trinh dang khdi qudt
Phuong trinh cdn bdng gidi ban cudng dp d i t n i n c6 t h i diln ta theo dang sau:
Pn = (Pm + Pxq) [1]
Trong dd:
Pz = Np+Npc = [(Nct+Pd)+Nc.Pc ]; Np=(Nct+Pd); Npc=Nc.Pc;
Pn=Pz+Fz
Hidn thudng dung cdeh tfnh ddng luc ty Id vdi trpng lupng cdng trinh Fz=k.Pz He sd dpng luc k thudng dung bdng tra s i n
=>Pn=Pz.(1+k); Pm =(Rd.Fc.Nc +Fn); Pxq = (Tbq.Sxq.L.Nc)
2 Phu'Png trinh dang khai trien Dang khai triln cu t h i hPn cd:
Np Fz+Pc.Nc = Fld.Fc.Nc+Nc.Tbq.sxq.L+Fn [2]
Hoac dudi dang rut gpn hon nQa da chpn chilu ddi cpc L vd cdc kfch thude mat d t ngang cpc trdn dudng kfnh D hoac cpc vudng a, cpc chQ nhdt a,b thi c6 the diJng phuong trinh dang:
VT=Nc.VF } [3] VT = (Np + Fz - Fn) } VF =(Rd Fc + Tbq Sxq L - yc Fc L) }
3 Cdc ky hieu d?i l u p n g vat ly
+ Np: Tai trpng k i t c l u cdng trinh vd cdc tdi trpng cong tdc truyin xudng d l mdng Net, trpng lupng ban
than ban d l mdng hay dai cpc Pd
+ Fz-Tong cac dpng luc tam thdi hoac luc xung tOc thdi c6 anh hudng d i n cudng dp chju tai eua n i n mdng cpc Hien thudng dung Fz=k.Pz nhu da neu tren
+ Fn-Tdng phan luc ngupe cua nudc ngam
n i n d i t bao hda d n ke d i n
+ Nc, L, Fc, Pc- s d cpc mdng Nc, chilu dai cpc L, dien tfch t i l t dien ngang mpt cpc Fc, trpng lupng ban than mpt cpc Pc
+ Rd, Tb, Sxq, •^c, yd- Qng s u i t phan luc d i u mui cpc Rd, Qng s u i t t i l p trung binh xung quanh than cpc Tbq, chu vi mat e l t ngang mpt cpc Sxq, trpng lupng ridng cua vat lieu lam cpc c, trpng lupng rieng ciia dat
nin d
Chi d l cap d i n kha nang chju cudng dp tai trpng cua cpc theo d i t n i n va coi nhu kha nang chju cudng dp tai trpng cua vat lieu cpc da dat yeu cau hay da xdt trudc rdi khdng c i n phaj d l cap d i n
III CAC HE QUA DAN XUAT
I T i m s d cpc Nc, da b i l t cpc ddi L va mat cat ngang Fc
a Cach tfnh hien hinh
Hien thuc t l tfnh toan dang sQ dung each tfnh toan tim sd cpc d n thilt bang each tim kha nang chju tai dQng cua mpt cpc Pcgh, rdi chia tai trpng thang dQng cho trj sd trpng tai dd, d l tim sd cpc c i n thilt, nhutrong cdc cdng thQc [a,b,c] sau:
L
Pcgh = Rd.Fc + \{T.Sxq).dz = Rd.Fc
• ^ {zbq.Sxq).Az 1=1
Pcgh = (Rd.Fc + Tbq.Sxq.L)
Pcgh
M
Pctt =
Fat
s d cpc d n thilt tdi t h i l u hay ft nhdt mdng Nc vd s6 cpc tfnh todn d n t h i l t bao dam an todn cdng trinh Nctt se la:
Pn Pn FatPn ^ , , , , Nc = => Nctt = = =FatNc [c]
Pcgh Pctt Pcgh
Trong dd: Pn = Pz.(l-i-k); vd thudng chpn Nctt > Nc.Fat
b Cach tfnh true tiip
He qua dupc khai trien tQ cac phuong trinh can bdng de tfnh true t i l p tim sd cpc ft n h i t Nc co dang:
Nc = } [4]
VF
VT = (Np + Fz - Fn) }
(2)T A I T R Q N G T H A N G o O l ^ G j
VF =(Rd.Fc + Tbq.Sxq.L - yc.Fc.L) } Vd c6 Nctt nhu tren :
.VT Fat.VT
Nctt = Fat.Ne }
Pctt Pcgh
Thudng chpn Nctt > Nc.Fat
Lfng s u i t phan luc tai mui cpc Rd thudng dung bang tra sdn theo k i t qua thuc nghiem vdi Rd=qp d l tfnh sd cpc, dd qp la sQc khang mui cpc gidi ban don vj cua d i t nen dudi d i u mOi cpc
2 Tim chiiu dii cgc L, di biit Nc vi Fc
a Tfnh theo kha nang chiu tii cua mdt cgc nhu each tfnh hien hinh
L = ( P c g h - Rd.Fc)/(Tbq.Sxq) [d] b Niu tfnh theo cich true thi theo cdng thUc [5]
06i vdi cpc chdng thi L >= H la dp sau cua t i n g da gdc hoac t i n g d i t cQng tua mui cpc chdng k i t qua khao sat cung d p tai lieu, khong d n tfnh todn thdm Rieng ddi vdi cpc treo hay cpc ma sdt thi cd the tfnh so bp chilu dai cpc L theo cong thQc:
VTz
LC = T T ^ } [5]
VFz
} VTz = (Np + Fz - Fn - Rd.Fc.Nc)
VFz = Nc.(Tbq.Sxq -yc.Fc) } Oa bilt kfch thude t i l t dien cpc Fc Sd cpc da djnh vj sdn Nc Chilu dai cpc Lc tfnh theo cdng thQc [5]
3 Cac bien phap khdc tfnh c h i l u ddi cpc L Ngoai cdc bidn phdp tren cdn cd t h i djnh lupng so bp L theo cac cong thQc khdc nhu sau:
a Mong cgc diiu kiin nin tU nhien + Tfnh Lz tu nhien mdng tach rdi
Chi khae sd hang Rd
VT
Rd=Rdz = Hoac Rd=Rdz=Lc.yd [6]
NcFc
+ Tfnh Lzb tu nhien mdng bd VT
Rd=Rdb = Hoac Rd=Rdb=Lc.yd
Fb
[7]
b Mong diiu kiin biin dang lun cho phep Sp ddi vdi tUng loai cdng trinh
Khi dd d n hieu chinh cdc so hang Rd theo ti>ng trudng hpp cu t h i
+> Tfnh Lp cho phep mdng tdch rdi Sp.E.]d
Rd-Rdz.i\-2v^)
+>Ti'nh Lpb cho phdp mdng bd:
Rd= 'P-^-^
[8]
[9]
Rdb.(l-2v^)
c Viic chon chiiu dii cgc tfnh toin Ltt
Hoac chpn Ltt= Lc [1 Oa] Hoac chpn Ltt=Lzp=(Lz+Lp)/2 • [10b]
Hoac chpn Ltt=(Lc+Lzp)/2 [10c] Hoac Ltt=Max(Lc,Lz,Lp) [lOd] Cac sd hang Lz va Lp tuong Qng vdi tQng loai
mong tach rdi hoac mdng bd
4.Tfnh mat cdt ngang mot cpc Fc, da b i l t Nc va L Viec chpn kich thude t i l t dien ngang cpc thudng
dua vdo ddc tamg d i t n i n vd kfch thude san xuat djnh hinh cac xudng due s i n vd cung d p vdi cdc lo^i cpc ddng hoac dp Ridng cdc cpc dd tai chd thi phai tfnh todn kfch thude t i l t dien ngang hpp ly Tuy nhien bidn phdp tfnh toan ndy ciing cd t h i sQ dung chung cho cdc loai cpc mdng c i n thilt
+ Cpc trdn dudng kfnh D c6 Fc=0,25.SD^ => D = 1.129 V ^
+ Cpc vudng canh a cd Fc=a.a => a= -JFC
+ Doi vdi cpc vuong d n tim c^nh a, cpc chQ nh|t
d n tim a vd b = axa vdi a =[1,3] thi Fc=a.b = a.a.a
=> a = •,J{Fe I a)
+ N I U tfnh theo khd nang chju tai eua cpc dPn nhu
trudc thi:
Fc = Pcgh/(Rd -nTbq.az L -yc.L) [g] + N I U tfnh theo cdeh true t i l p thi theo cdng thQc sau:
VTc
'"Wo ' '"' VTc = (Np + Fz - Fn) } VFc = Ne.(Rd-Kxz.Tbq.L -yc.L) }
az = Sxq/Fc } IV KET LUAN
Vide trinh bdy khdi qudt ndy d l cap d i n trudng hop chi xdt tdi trpng t h i n g dQng cdng trinh truyin xudng ndn mdng cpc Odi vdi cdc loai tai trpng ngang, momen udn tac dung tai d i u trdn cua cpc Id nhQng vdn d§ phQc tap thudng dupe nghien cQu tdch ridng vdi trudng hpp tai trpng t h i n g dQng cdng trinh truyin xudng d i t n i n Vide djnh lupng thdnh p h i n tdi trpng dong, ode xung luc tdc ddng vdo n i n mdng cdng trinh Fz rit phQc tap Cdc y l u td dnh hudng luc eung phQc tap nufa nhu phdn luc d i u mui cpc, luc t i l p tuyen hay ma sdt xung quanh cpc vdi ddt n i n , phdn luc ngupe tac dpng nudc n g i m n i n bao hda nudc Fn Id nhQng dai lupng khd djnh lupng, thudng sQ dung theo kinh nghidm sdn cd tra cQu qui pham thilt k l hidn hdnh hoac cd nhQng bidn phdp tfnh khdc
Tdc gid d l x u i t cdc edch tfnh true t i l p vd cdc h§ qua d i n x u i t , thilt lap cdc cdng thQc tfnh todn ddnh sd tQ [1] d i n [11] Cd t h i Qng dung tfnh todn sO bp ode kfch thude cpc, sd cpc ndn mdng coc theo phuong tidn tfnh thu cdng hoac ldp trinh theo phuong phdp sd gidi bdng mdy vi tfnh Hien tdc gid da lap trinh vd chay thQ nghidm mdt chuong trinh PILEFOUND ngon ngO VB d l gidi quylt cdc loai bdi toan ndy tuong ddi tien dung, k i t qua khd tuong duong vd phu hpp vdi thuc t l ; tdc dp n h i n nut Id cd k i t qud chua d i n mpt gidy r i t cao tdc, nhanh chdng
Viec phdt t r i l n Idm thay ddi hinh thQc vd npi dung phuong phdp tfnh todn thilt k l n i n mdng cpc ndi Chung doi vdi cac loai n i n mdng cpc thudng gap da Idm ndi trpi nhQng khfa canh mdi me ro ret vd tao thudn tien hon nOa ddi vdi vide Qng dung cdng nghd tin hpc tfnh todn sd ddi vdi ndn mdng cpc, gpn gang vd tien dung hon.a