自己的沖刷公式

1、河灘部分一般沖刷,,,注:非粘性土河床的一般沖刷(就一個公式),,,,,,,,,

hp=[(htm/htq)5/3Q1/(μBtj)/(VH1)]5/6,,,,,Q1=QPQt1/(QC+Qt1),,,,,,,

htm—橋下河灘最大水深；123.45－116.75=6.70m,,,,,,,,,,,,

htq—橋下河灘平均水深；6.0m,,,,,,,,,需要填充的數(shù)據(jù),,,

Btj—河灘部分橋孔凈長；1240－362－38=840m,,,,,,,,,,,,

VH1—河灘水深1m時非粘性土不沖刷流速；0.38m/s,,,,,,,,,,,,

htm,Btj,VH1,htq,μ,QP,QC,Qt1,,,,,

6.5,1125.97,0.33,5.22,0.995,24300,7123,16974,,,,,

Q1=,17116.99,,,,,,,,,,,

hp=,33.13,17.174,,,,,,,,,,

h=,26.63,10.674,,,,,,,,,,

2、河槽部分一般沖刷計算,,,,注:64-2簡化式非粘性土河床的一般沖刷,,,,,,,,

hp=1.04(AdQ2/QC)0.90{BC/[(1－λ)μBcg]}0.66hcm,,,,,,,Ad—單寬流量集中系數(shù),,,,,

,,,,,,,Ad=(√BC/HC)0.15,,,,,

BC—天然狀態(tài)下河槽寬度；362m,,,,,,,BC,HC,,,,

HC—平灘水位時河槽平均水深；4.04m,,,,,,,500,4.17,,,,

Q2—橋下河槽部分通過的設計流量；,,,,,,Ad=,1.29,,,,,

Q2=QPQC/(QC+Qt1),,,,,,,,,,,,

hcm,Bc,μ,QP,QC,Qt1,λ,Bcg,,,,,

11.15,500,0.995,24300,7123,16974,0.067,500,,,,,

Q2=,7183.01,,,,,,,,,,,

hp=,15.39,,,,,,,,,,,

h=,4.24,,,,,,,,,,,

3、河灘局部沖刷,,,注:65-1,,,,,,,,,

按65-1式計算,,,,,,,,,,,,

V=Ed1/6hp2/3,,,式中：V—一般沖刷后墩前行進流速；,,,,,,,,,

E,d,hp,Kξ,L,b,B1,n1,,,,,

0.46,0.2,17.17,1,6,4,2,0.62,,,,,

V=,2.34,V0=,0.57,Kη1=,2.67,V'0=,0.23,hb,4.25,,,

V0=0.0246(hp/d)0.14√(332d+(10+hp)/d0.72),,,,,E-含砂率，見P28,,,,,,,

式中：V0—河床泥沙起動流速；,,,,,,,0.081747645,,,,,

∵V>V0,,,,,,,,,,,,

∴hb=KξKη1B10.6(V－V0’)/[(V－V0’)/(V0－V0’)]n1,,,,,,,,,,,,

式中：Kξ—墩形系數(shù)；Kξ=1.10,,,,,,,,,,,,

B1—橋墩計算寬度；B1=L－b=6－4=2m,,,,,,,,,,,,

Kη1—河床顆粒影響系數(shù)；,,,,,,,,,,,,

Kη1=0.8(1/d0.45+1/d0.15),,,,,,,,,,,,

V0’—墩前泥沙始沖流速；,,,,,,,,,,,,

V0’=0.462(d/B1)0.06V0,,,,,,,,,,,,

式中：d—河床泥沙平均粒徑;0.5mm(由地質資料可知),,,,,,,,,,,,

n1—指數(shù),,,,,,,,,,,,

n1=(V0/V)**（0.25d-0.19）,,,,,,,,,,,,

4、河槽橋墩局部沖刷,,,,,,按65—2式計算,,,,,,

V0=0.28(d+0.7)0.5,,,,,,,,,,,,

式中：V0—河床泥沙起動流速；,,,,,,,,,,Ad—單寬流量集中系數(shù),,

V=(Ad0.1/1.04)(Q2/QC)0.1{BC/[(1－λ)μBcg)]}0.34(hcm/hc)2/3VC,,,,,,,,,,Ad=(√BC/HC)0.15,,

式中：V—一般沖刷后墩前行進流速；,,,,,,,,,,BC,HC,

HC—平灘水位時河槽平均水深；4.04m,,,,,,,,,,500,4.17,

Q2—橋下河槽部分通過的設計流量；,,,,,,,,,Ad=,1.29,,

Q2=QPQC/(QC+Qt1),,,,,,,,,,,,

QC—天然狀態(tài)下河槽流量；6700m3/s,,,,,,,,,,,,

Qp—設計流量；13960m3/s,,,,,,,,,,,,

hcm,Bc,μ,QP,QC,Qt1,λ,Bcg,VC,hC,d,V0,Kξ

11.15,500,0.995,24300,7123,16974,0.067,500,1.54,9.25,0.2,0.27,1.1

Q2=,7183.01,hp=,15.39,Kη2=,0.33,V'0=,0.10,n2=,0.83,B1,,

V=,1.77,hb=,3.87,,,,,,,2,,

式中：V—一般沖刷后墩前行進流速；,,,,,,,V0’—墩前泥沙始沖流速；,,,,,

∵V>V0,,,,,,,V0’=0.12(d+0.5)0.55,,,,,

∴hb=KξKη2B10.6hp0.15[(V－V0’)/V0]n2,,,,,,,n2—指數(shù)；,,,,,

式中：Kξ—墩形系數(shù)；Kξ=1.10,,,,,,,n2=(V0/V)0.23+0.19lgd,,,,,

B1—橋墩計算寬度；B1=L－b=6－4=2m,,,,,,,,,,,,

hp=1.04(AdQ2/QC)0.90{BC/[(1－λ)μBcg)]}0.66hcm,,,,,,,,,,,,

Kη2—河床顆粒影響系數(shù)；Kη2=0.375d0.24+0.0023/d2.2,,,,,,,,,,,,

,"按6.2.1—1式計算,Lj=Kq(QP/QC)n3Bc",,,,,,,,,,,

,Kp,Qp,Qc,n3,Bc,,,,,,,

,0.95,24300,7123,0.87,500,,,,,,,

,Lj,1381.51,,,,,,,,,,

,"按6.2.1—2式計算,Lj=QP/(βqC),β=1.19(Qc/Qt)0.10",,,,,,,,,,,

,β—