双孔涵洞结构计算实例

席家泵站涵洞结构计算书一、已知条件

堤顶至顶板填土高度H d=1.08m

填土内摩擦角φ=25°

洞身每孔净宽B=2m

洞身每孔净高H=2m

底板厚d1=0.4m

顶板厚d2=0.4m

侧墙厚d3=0.4m

中隔板厚d4=0.3m

过流量Q=5.50m3/s

混凝土强度等级C25

工况为洞内无水

0.2*0.2

二、荷载计算

1、作用于洞顶的均布垂直土压力q t2

H d /B 1=1.08/5.1=0.02，查表得K s =1.0。 q t2=1.20×K s γH d =1.20×1.0×18×1.08=23.33kN/m 2、作用于侧墙水平分布土压力q t3、q t4 q t3=1.20×γ(H d +d 2)tan 2(45-2

φ)

=1.20×18×(1.08+0.4)tan 2

(45°-2

250

)=12.97kN/m

q t4=1.20×γ(H d +d 2+H)tan 2(45-2

φ)

=1.20×18×(1.08+0.4+2.0)tan 2

(45°-2

250

)=30.51kN/m

作用于侧墙的荷载无水压力，则 q 3=q t3=12.97 kN/m ，q 4=q t4=30.51 kN/m 3、洞顶承受的车辆荷载Q Q=

A P

=()()

4.230tan 26.130tan 219600++d d H H =

(

)()

4

.230tan 08.126.130tan 08.12196

0+⨯⨯+⨯⨯=18.87 kN/m 3、作用于顶板的垂直均布荷载总和q 2

q 2=q t2+1.05×γc d 2+1.2×Q=23.33+1.05×25×0.4+1.2×18.87=56.47kN/m 4、作用于底板底面的垂直均布荷载总和q 1 q 1=q 2+

1

43)

2(05.1B d d H c +γ

=56.47+1.05×25×2×(2×0.4+0.3)/5.1 =67.79 kN/m 二、固端弯矩计算

M F

AC =-12212L q =-12

35.247.562

⨯=-25.99kN·m

M F CA =- M F AC =25.99kN·m

M F

BD =12

211L q =1235.279.672

⨯=31.20kN·m

M F DB =- M F BD =-31.20kN·m

M F AB =()30

122

234223L

q q L q -+

=

()30

4.297.1251.3012

4.297.122

2

⨯-+

⨯=9.59kN·m

M F

BA =()20

12223422

3L q q L q --- =()20

4.297.1251.3012

4.297.122

2

⨯--

⨯-

=-11.28kN·m

三、抗弯劲度系数

K AC =132124L d =35

.2124.043

⨯⨯=0.00908

K BD =131124L d =35

.2124.043

⨯⨯=0.00908

K AB =K BA =2

33124L d =4.2124.043

⨯⨯=0.00889

四、杆端弯矩分配系数 μAC =AB AC AC K K K +=00889.000908.000908.0+=0.505

μAB =AB AC AB K K K +=00889.000908.000889

.0+=0.495

μBA =

BD BA BA K K K +=00908

.000889.000889

.0+=0.495

μBD =

BD BA BD K K K +=00908

.000889.000908

.0+=0.505

五、杆端弯矩传递系数

各杆件向远端传递系数均为1/2。 六、节点弯矩分配计算

七、各部位剪力、轴力及控制截面弯矩计算 1、顶板AC 和底板BD 剪力计算 Q AC =1

122L M M L q AC

AC +- =

35

.273

.3152.14235.247.56+--

⨯=59.03kN

Q CA =1

122L M M L q AC

AC +-- =35

.273

.3152.14235.247.56+--

⨯-

=-73.68kN Q DB =1

112L M M L q BD DB +- =

35

.230

.1863.37235.279.67+--

⨯=87.88kN Q BD =1

112L M M L q BD DB +-- =35

.230

.1863.37235.279.67+--

⨯-

=-71.43kN 2、侧墙AB 剪力计算 Q AB =2

234243)(2L M M L q q L q BA AB +--+- =()4

.230

.1852.1434.297.1251.3024.251.30--

⨯-+⨯-

=-21.01kN Q BA =2

234246)(2L M M L q q L q BA AB +--- =

()4

.230

.1852.1464.297.1251.3024.251.30--

⨯--⨯ =31.18kN

3、各加腋起点截面弯矩和跨间最大弯矩 加腋尺寸：0.2m×0.2m

底板(D)：x 1左=L 1-d 3/2-0.2=2.35-0.4/2-0.2=1.95m x 1右=0.2+d 4/2=0.2+0.3/2=0.35m 顶板(A)：x 2左=x 1右=0.35m x 2右=x 1左=1.95m