Flow influence line-based mountain torrent prewarning method for small and medium bridges

Abstract

The invention relates to a flow influence line-based mountain torrent prewarning method for small and medium bridges, comprising the following steps of: through calibrating a water mark elevation, actually measuring or determining a flow Qs of a bridge site section below the water mark elevation by utilizing a manning formula, corresponding water rising duration time T1 and water-break duration time T2 and a rainfall series generating the water mark elevation; assuming a maximum value Cmax of the flow influence line, calculating the maximum flow of the corresponding rainfall series according to a flow influence line formula, and comparing the maximum flow with the Qs; selecting the Cmax value satisfying the precision requirement; and determining the flow influence line of the corresponding bridge; and then calculating the real time flow according to the flow influence line and the real time rainfall, and carrying out hydrological checking on the bridge and prewarning. The method is simple and convenient for operation, the flow influence line is calibrated by utilizing the historical water mark, the flow is calculated according to the rainfall series, the flood damage degree and the time of a flood peak reaching the bridge are predicted, the precision is high; and the method is suitable for predicting flood damage of the small and medium bridges.

Description

technical field

[0001] The invention discloses a flash flood warning method for medium and small bridges based on flow influence lines, and belongs to the interdisciplinary technical field of hydrology and structural mechanics. Background technique

[0002] Flood damage to bridges is a serious natural disaster faced by bridge communities all over the world. The analysis of 500 bridges destroyed in the United States from 1989 to 2000 shows that floods and impacts caused the highest frequency of bridge failures. In 1993 alone, the proportion of bridges damaged by flooding and erosion was as high as 53%.

[0003] At present, in the field of hydrology, the flow unit line method proposed by J.E Nashi is often used to estimate the flow of small and medium bridges based on rainfall. The unit line method has the following three assumptions

[0004] Assume that the 1 unit line flow has a linear relationship with the net rain;

[0005] Assume 2 that the bottom length of the unit li...

Examples

specific Embodiment 1

[0119] Specific Example 1——Maojiang Bridge on Shanghai-Kunming Line

[0120] 1. Survey results

[0121] 1.1 River bottom line of bridge site section

[0122] Table 1 River Bottom Line of Maojiang Bridge Site Section of Shanghai-Kunming Line

[0123] i

1

2

3

4

5

6

7

8

9

10

11

12

x

01.14

08.04

14.89

19.29

21.6

24.19

30.54

33.19

43.4

44.64

52.34

52.34

y

78.10

71.60

71.10

70.80

70.60

69.80

69.50

69.80

70.70

71.10

78.1

78.10

[0124] In Table 1: x is the distance (m), and y is the elevation (m).

[0125] 1.2 Roughness coefficient

[0126] The x of the intersection of the left bank and the main slot z =21.6(m), x of intersection point of right bank and main groove y = 43.4(m).

[0127] left beach roughness coefficient Main groove roughness coefficient Roughness co...

Embodiment 2

[0281] Embodiment 2 - Daguan Bridge on Beijing-Guangzhou Line

[0282] 1. Survey results

[0283] 1.1 River Bottom Line

[0284] Table 2 The Bottom Line of Daguanqiao River on Beijing-Guangzhou Line

[0285]

[0286] In Table 2, x is the distance (m), and y is the elevation (m).

[0287] 1.2 Roughness coefficient

[0288] The intersection coordinates of the left bank and the main groove (12.1, 29.8), and the coordinates of the intersection point of the right bank and the main groove (22.8, 30.2).

[0289] Left beach roughness coefficient N z =15, main groove roughness coefficient N zh =32, right beach roughness coefficient N y =15.

[0290] 1.3 Slope of the water surface in front of the bridge

[0291] I=0.0025(rad)

[0292] 1.4 Distance from the basin center to the bridge site

[0293] L h =4(km)

[0294] 1.5 Elevation of the water mark left on the pier by the flood on May 28, 2008

[0295] h b =32.7(m)

[0296] 2. Calculate by the following steps of the pre...

technical field

[0001] The invention discloses a flash flood warning method for medium and small bridges based on flow influence lines, and belongs to the interdisciplinary technical field of hydrology and structural mechanics. Background technique

[0002] Flood damage to bridges is a serious natural disaster faced by bridge communities all over the world. The analysis of 500 bridges destroyed in the United States from 1989 to 2000 shows that floods and impacts caused the highest frequency of bridge failures. In 1993 alone, the proportion of bridges damaged by flooding and erosion was as high as 53%.

[0003] At present, in the field of hydrology, the flow unit line method proposed by J.E Nashi is often used to estimate the flow of small and medium bridges based on rainfall. The unit line method has the following three assumptions

[0004] Assume that the 1 unit line flow has a linear relationship with the net rain;

[0005] Assume 2 that the bottom length of the unit li...

Examples

specific Embodiment 1

[0119] Specific Example 1——Maojiang Bridge on Shanghai-Kunming Line

[0120] 1. Survey results

[0121] 1.1 River bottom line of bridge site section

[0122] Table 1 River Bottom Line of Maojiang Bridge Site Section of Shanghai-Kunming Line

[0123] i

1

2

3

4

5

6

7

8

9

10

11

12

x

01.14

08.04

14.89

19.29

21.6

24.19

30.54

33.19

43.4

44.64

52.34

52.34

y

78.10

71.60

71.10

70.80

70.60

69.80

69.50

69.80

70.70

71.10

78.1

78.10

[0124] In Table 1: x is the distance (m), and y is the elevation (m).

[0125] 1.2 Roughness coefficient

[0126] The x of the intersection of the left bank and the main slot z =21.6(m), x of intersection point of right bank and main groove y = 43.4(m).

[0127] left beach roughness coefficient Main groove roughness coefficient Roughness co...

Embodiment 2

[0281] Embodiment 2 - Daguan Bridge on Beijing-Guangzhou Line

[0282] 1. Survey results

[0283] 1.1 River Bottom Line

[0284] Table 2 The Bottom Line of Daguanqiao River on Beijing-Guangzhou Line

[0285]

[0286] In Table 2, x is the distance (m), and y is the elevation (m).

[0287] 1.2 Roughness coefficient

[0288] The intersection coordinates of the left bank and the main groove (12.1, 29.8), and the coordinates of the intersection point of the right bank and the main groove (22.8, 30.2).

[0289] Left beach roughness coefficient N z =15, main groove roughness coefficient N zh =32, right beach roughness coefficient N y =15.

[0290] 1.3 Slope of the water surface in front of the bridge

[0291] I=0.0025(rad)

[0292] 1.4 Distance from the basin center to the bridge site

[0293] L h =4(km)

[0294] 1.5 Elevation of the water mark left on the pier by the flood on May 28, 2008

[0295] h b =32.7(m)

[0296] 2. Calculate by the following steps of the pre...

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