悬臂支护结构设计计算书Word文档格式.docx
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水土分算
填土
2
19
10
20
否
粘性土
3.5
21
15
18
22
是
16
3、荷载参数
类型
荷载q(kpa)
距支护边缘的水平距离a(m)
垂直基坑边的分布宽度b(m)
平行基坑边的分布长度l(m)
作用深度d(m)
满布荷载
/
条形局部荷载
4
矩形局部荷载
5
4、计算系数
结构重要性系数γ0
1
综合分项系数γF
1.25
嵌固稳定安全系数Ke
圆弧滑动稳定安全系数Ks
1.3
突涌稳定安全系数Kh
1.1
二、土压力计算
土压力分布示意图
附加荷载布置图
1、主动土压力计算
1)主动土压力系数
Ka1=tan2(45°
-φ1/2)=tan2(45-12/2)=0.656;
Ka2=tan2(45°
-φ2/2)=tan2(45-12/2)=0.656;
Ka3=tan2(45°
-φ3/2)=tan2(45-18/2)=0.528;
Ka4=tan2(45°
-φ4/2)=tan2(45-18/2)=0.528;
2)土压力、地下水产生的水平荷载
第1层土:
0-0.8m
H1'
=[∑γ0h0+∑q1]/γi=[0+3]/19=0.158m
Pak1上=γ1H1'
Ka1-2c1Ka10.5=19×
0.158×
0.656-2×
10×
0.6560.5=-14.229kN/m2
Pak1下=γ1(h1+H1'
)Ka1-2c1Ka10.5=19×
(0.8+0.158)×
0.6560.5=-4.258kN/m2
第2层土:
0.8-2m
H2'
=[∑γ1h1+∑q1]/γsati=[15.2+3]/20=0.91m
Pak2上=γsat2H2'
Ka2-2c2Ka20.5=20×
0.91×
0.6560.5=-4.26kN/m2
Pak2下=γsat2(h2+H2'
)Ka2-2c2Ka20.5=20×
(1.2+0.91)×
0.6560.5=11.484kN/m2
第3层土:
2-4m
H3'
=[∑γ2h2+∑q1]/γsati=[39.2+3]/22=1.918m
Pak3上=[γsat3H3'
-γw(∑h2-ha)]Ka3-2c3Ka30.5+γw(∑h2-ha)=[22×
1.918-10×
(2-0.8)]×
0.528-2×
15×
0.5280.5+10×
(2-0.8)=6.144kN/m2
Pak3下=[γsat3(H3'
+h3)-γw(∑h2-ha)]Ka3-2c3Ka30.5+γw(∑h2-ha)=[22×
(1.918+2)-10×
(4-0.8)]×
(4-0.8)=38.816kN/m2
第4层土:
4-5.5m
H4'
=[∑γ3h3+∑q1+∑q1b1/(b1+2a1)]/γsati=[83.2+3+1.167]/22=3.971m
Pak4上=[γsat4H4'
-γw(∑h3-ha)]Ka4-2c4Ka40.5+γw(∑h3-ha)=[22×
3.971-10×
(4-0.8)=39.432kN/m2
Pak4下=[γsat4(H4'
+h4)-γw(∑h3-ha)]Ka4-2c4Ka40.5+γw(∑h3-ha)=[22×
(3.971+1.5)-10×
(5.5-0.8)]×
(5.5-0.8)=63.936kN/m2
3)水平荷载
临界深度:
Z0=Pak2下h2/(Pak2上+Pak2下)=11.484×
1.2/(4.26+11.484)=0.875m;
第1层土
Eak1=0kN;
第2层土
Eak2=0.5Pak2下Z0ba=0.5×
11.484×
0.875×
0.5=2.512kN;
aa2=Z0/3+∑h3=0.875/3+3.5=3.792m;
第3层土
Eak3=h3(Pa3上+Pa3下)ba/2=2×
(6.144+38.816)×
0.5/2=22.48kN;
aa3=h3(2Pa3上+Pa3下)/(3Pa3上+3Pa3下)+∑h4=2×
(2×
6.144+38.816)/(3×
6.144+3×
38.816)+1.5=2.258m;
第4层土
Eak4=h4(Pa4上+Pa4下)ba/2=1.5×
(39.432+63.936)×
0.5/2=38.763kN;
aa4=h4(2Pa4上+Pa4下)/(3Pa4上+3Pa4下)=1.5×
39.432+63.936)/(3×
39.432+3×
63.936)=0.691m;
土压力合力:
Eak=ΣEaki=0+2.512+22.48+38.763=63.755kN;
合力作用点:
aa=Σ(aaiEaki)/Eak=(0×
0+3.792×
2.512+2.258×
22.48+0.691×
38.763)/63.755=1.366m;
2、被动土压力计算
1)被动土压力系数
Kp1=tan2(45°
+φ1/2)=tan2(45+18/2)=1.894;
Kp2=tan2(45°
+φ2/2)=tan2(45+18/2)=1.894;
2.5-3.7m
=[∑γ0h0]/γi=[0]/21=0m
Ppk1上=γ1H1'
Kp1+2c1Kp10.5=21×
0×
1.894+2×
1.8940.5=41.287kN/m2
Ppk1下=γ1(h1+H1'
)Kp1+2c1Kp10.5=21×
(1.2+0)×
1.8940.5=89.016kN/m2
3.7-5.5m
=[∑γ1h1]/γsati=[25.2]/22=1.145m
Ppk2上=[γsat2H2'
-γw(∑h1-hp)]Kp2+2c2Kp20.5+γw(∑h1-hp)=[22×
1.145-10×
(1.2-1.2)]×
1.8940.5+10×
(1.2-1.2)=88.997kN/m2
Ppk2下=[γsat2(H2'
+h2)-γw(∑h1-hp)]Kp2+2c2Kp20.5+γw(∑h1-hp)=[22×
(1.145+1.8)-10×
(3-1.2)]×
(3-1.2)=147.907kN/m2
Epk1=bah1(Pp1上+Pp1下)/2=0.5×
1.2×
(41.287+89.016)/2=39.091kN;
ap1=h1(2Pp1上+Pp1下)/(3Pp1上+3Pp1下)+∑h2=1.2×
41.287+89.016)/(3×
41.287+3×
89.016)+1.8=2.327m;
Epk2=bah2(Pp2上+Pp2下)/2=0.5×
1.8×
(88.997+147.907)/2=106.607kN;
ap2=h2(2Pp2上+Pp2下)/(3Pp2上+3Pp2下)=1.8×
88.997+147.907)/(3×
88.997+3×
147.907)=0.825m;
Epk=ΣEpki=39.091+106.607=145.698kN;
ap=Σ(apiEpki)/Epk=(2.327×
39.091+0.825×
106.607)/145.698=1.228m;
3、基坑内侧土反力计算
-φ1/2)=tan2(45-18/2)=0.528;
-φ2/2)=tan2(45-18/2)=0.528;
Psk1上=(0.2φ12-φ1+c1)∑h0(1-∑h0/ld)υ/υb+γ1H1'
Ka1=(0.2×
182-18+15)×
(1-0/3)×
0.012/0.012+21×
0.528=0kN/m2
Psk1下=(0.2φ12-φ1+c1)∑h1(1-∑h1/ld)υ/υb+γ1(h1+H1'
)Ka1=(0.2×
(1-1.2/3)×
(0+1.2)×
0.528=57.802kN/m2
Psk2上=(0.2φ22-φ2+c2)∑h1(1-∑h1/ld)υ/υb+[γsat2H2'
-γw(∑h1-hp)]Kp2+γw(∑h1-hp)=(0.2×
12/12+[22×
0.528+10×
(1.2-1.2)=57.796kN/m2
Psk2下=(0.2φ22-φ2+c2)∑h2(1-∑h2/ld)υ/υb+[γsat2(H2'
+h2)-γw(∑h2-hp)]Kp2+γw(∑h2-hp)=(0.2×
3×
(1-3/3)×
(3-1.2)=42.705kN/m2
Psk1=b0h1(Ps1上+Ps1下)/2=0.5×
(0+57.802)/2=17.341kN;
as1=h1(2Ps1上+Ps1下)/(3Ps1上+3Ps1下)+∑h2=1.2×
0+57.802)/(3×
0+3×
57.802)+1.8=2.2m;
Psk2=b0h2(Ps2上+Ps2下)/2=0.5×
(57.796+42.705)/2=45.225kN;
as2=h2(2Ps2上+Ps2下)/(3Ps2上+3Ps2下)=1.8×
57.796+42.705)/(3×
57.796+3×
42.705)=0.945m;
Ppk=ΣPpki=17.341+45.225=62.566kN;
as=Σ(asiPski)/Ppk=(2.2×
17.341+0.945×
45.225)/62.566=1.293m;
Psk=62.566kN≤Ep=145.698kN
满足要求!
三、稳定性验算
1、嵌固稳定性验算
Epkapl/(Eakaal)=145.698×
1.228/(63.755×
1.366)=2.054≥Ke=1.2
2、整体滑动稳定性验算
圆弧滑动条分法示意图
Ksi=∑{cjlj+[(qjbj+ΔGj)cosθj-μjlj]tanφj}/∑(qjbj+ΔGj)sinθ
cj、φj──第j土条滑弧面处土的粘聚力(kPa)、内摩擦角(°
);
bj──第j土条的宽度(m);
θj──第j土条滑弧面中点处的法线与垂直面的夹角(°
lj──第j土条的滑弧段长度(m),取lj=bj/cosθj;
qj──作用在第j土条上的附加分布荷载标准值(kPa);
ΔGj──第j土条的自重(kN),按天然重度计算;
uj──第j土条在滑弧面上的孔隙水压力(kPa),采用落底式截水帷幕时,对地下水位以下的砂土、碎石土、粉土,在基坑外侧,可取uj=γwhwaj,在基坑内侧,可取uj=γwhwpj;
滑弧面在地下水位以上或对地下水位以下的粘性土,取uj=0;
γw──地下水重度(kN/m3);
hwaj──基坑外侧第j土条滑弧面中点的压力水头(m);
hwpj──基坑内侧第j土条滑弧面中点的压力水头(m);
min{Ks1,Ks2,……,Ksi,……}=1.741≥Ks=1.3
3、渗透稳定性验算
渗透稳定性简图
承压水作用下的坑底突涌稳定性验算:
Dγ/(hwγw)=∑hiγi/(hwγw)=(3.5×
21)/(6×
10)=1.225
Dγ/(hwγw)=1.225≥Kh=1.1
四、结构计算
1、材料参数
钢桩类型
槽钢
钢桩型号
20a号槽钢
钢材的惯性矩I(cm4)
1780.4
钢材的截面抵抗矩W(cm3)
178
钢材的弹性模量E(N/mm2)
20600
钢材的抗弯强度设计值f(N/mm2)
205
钢材的抗剪强度设计值τ(N/mm2)
125
材料截面塑性发展系数γ
1.05
2、支护桩的受力简图
计算简图
弯矩图(kN·
m)
Mk=14.917kN.m
剪力图(kN)
Vk=37.58kN
3、强度设计值确定
M=γ0γFMk=1×
1.25×
14.917=18.646kN·
m
V=γ0γFVk=1×
37.58=46.975kN
4、材料的强度计算
σmax=M/(γW)=18.646×
106/(1.05×
178×
103)=99.765N/mm2≤[f]=205N/mm2
b`=(hb2-(b-tw)2(h-2t))/(2(hb-(b-tw)(h-2t))=(200×
732-(73-7)2(200-2×
11))/(2(200×
73-(73-7)(200-2×
11))=51mm
S=t(b-b`)2=11×
(73-51)2=5324mm3,
τmax=VS/It=46.975×
5324×
103/(1780.4×
104×
11)=1.277N/mm2≤[f]=125N/mm2