1. Luis Leonardo González Jiménez; CE, MSc Jorge Enrique Saénz Samper; CE
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INCIDENCE OF THE NEW BRIDGE CONSTRUCTION OVER THE MAGDALENA RIVER IN BARRANQUILLA (COLOMBIA) ON THE HYDRAULIC CONDITIONS
Luis Leonardo González Jiménez; CE, MSc
Jorge Enrique Saénz Samper; CE
Pittsburgh, USA, September 2017

2. INTRODUCTION
The objective of the study was evaluating the influence of the new bridge construction on the river hydraulics near the crossing. New bridge is located parallel to the existing one.
- Existing bridge: piles arranged in pairs with 2.5m diameter each and 5m diameter for the central piers.
- New bridge: span of 380m between central piers, each one supported on a dice with piles of 2.8m diameter.
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3. 1- Water levels at Canchera School
Main Topics Analyzed
1- Water levels at Canchera School
2- Hydraulics and scouring at the New Bridge
3- Pasadena Channel Hydraulics
4- Ahuyama Branch Hydraulics
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4. N Location CARIBBEAN SEA PACIFIC OCEAN 19-09-2017 “SMART RIVERS 2017”
New Bridge Piles
Barranquilla
To San Marta
Existing Bridge
Rondón Island
MAGDALENA RIVER
CARIBBEAN SEA
PACIFIC OCEAN
Barranquilla
MAGDALENA RIVER
Location New Bridge N
Barranquilla
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5. Magdalena River General Characteristics
Width of the Magdalena River on site: 1150 m
Mean Annual Discharge :7200 m3/s
Distance to Caribbean Sea: 21 km
Manning’s n Main channel: 0.024
- Manning’s n Island and banks: 0.035
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6. 1- Water levels at Canchera School
MAGDALENA
RIVER
Existing Bridge
New Bridge Piles
500 m aprox N
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7. 1- Water levels at Canchera School
Based on the topographic information and the hydraulic modeling, water levels that can be reached by the river and affected property were stablished.
Magdalena River
Location current Bridge and New Bridge
Aprox 500 m
Hydraulic Profiles
Site closest to Canchera School
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8. 1- Water levels at Canchera School
For the construction of the Canchera School, a period return period of 50 years was considered.
Return Period
(Years)
Water Level (msnm)
Protection Level
(msnm) 5
1.98
2.13 10
2.21
2.36 20
2.40
2.55 50
2.61
2.76
100
2.75
2.90
It was recommended to raise the terrain level to a height of 2 masl. The first floor should start at 2.75 masl.
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9. 2- Pasadena channel hydraulics
CHANNEL PASADENA
MAGDALENA RIVER
BARRANQUILLA
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10. 2- Pasadena Channel hydraulics
According to the topography of the area, the channel projected for the Channel Pasadena in the sector where the camp is located is hydraulically studied. This included hydrology, channel layout and cross-sections.
Hydraulic Modeling - HECRAS
- Design flow - Tr 50 years: 10.8 m3/s corresponding to 54 ha
Boundary Conditions: Levels in the Magdalena river at the place of channel delivery and variation of water levels by tide effect.
Manning’s n: 0.015, corresponding to concrete
Slopes: 0.12% and 0.64%
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11. 2- Pasadena channel hydraulics
Channel bottom is below the natural terrain as a result of the interference with existing pipes and cross section changes.
The possibility of a hydraulic jump for a period of Tr = 50 years and a minimum level in the Magdalena river was considered. Although improbable, it will happen in the lined section of the channel and will be submerged by the water level of the Magdalena River.
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12. 3- Hydraulic Evaluation and Scouring at the New Bridge
Analysis were conducted to study the behavior of the river at the project site during the construction of the new bridge.
This condition is considered the most critical during the next 3 years and which will be at the same time the following structures:
Piles of the existing bridge
Piles of the new bridge
Four temporary jetties for construction of the new bridge
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13. 3- Hydraulic Evaluation and Scouring at the New Bridge
Palermo
Piles of the existing bridge
Rondón Island
380 m
Piles of the New Bridge
Barranquilla
Temporary jetties for construction of the new Bridge
Magdalena River N
Rondón Island
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14. 3- Hydraulic Evaluation and Scouring at the New Bridge
Piles of the existing bridge = 30 piles
Piles of the new bridge = 54 piles, 2.0m diam + 20 Piles, 2.8m
Four temporary jetties during construction
2*( )= 258 piles, 0,90m diam.
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15. 3- Hydraulic Evaluation and Scouring at the New Bridge
Hydraulic Modeling
New bridge
Existing bridge
Jetty
Magdalena River
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16. 3- Hydraulic Evaluation and Scouring of the New Bridge
Model Results
Return Period (years)
Flow
(m3/s)
Water level (masl)
Existing bridge Scenario
Scenario during construction
Future scenario only with the New bridge
Original design (2014)
Jesyca (2015) 2
11 819
1.63
1.64 5
13 790
2.08
2.11
2.09 10
14 800
2.32
2.35
2.33 20
15 619
2.52
2.55
2.53 50
16 521
2.74
2.77
2.75
100
17 111
2.89
2.92
500
18 279
3.18
3.21
1000
18 717
3.29
3.32
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17. 3- Hydraulic Evaluation and Scouring at the New Bridge
It can be concluded that the effect of the piles during construction on the hydraulic behavior of the Magdalena River, is minimal and does not imply any complication from the point of view of changes in the water levels or the average velocities in the central channel or the banks.
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18. 3- Hydraulic Evaluation and Scouring of the New Bridge
General scour was estimated by the Lischtvan-Lebediev formulation. Local scour by the formulations in HEC-18 for a composite pile.
According to the total estimated scour, the final profile theoretically exceeds the coral rock boundary.
Since it is a competent stratum, the scour is limited to rock level.
Longitudinal profile main channel
Maximun water level 3.13 masl - Average water level 1.69 masl
Scour estimated assuming sandy bed
Coral rock
Shallow fill
Alluvial filling
Alluvial - Lacustrine filling
Residual Soil 1
Residual Soil 2
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19. 4- Ahuyama branch hydraulics
MAGDALENA RIVER N
BARRANQUILLA
CAÑO AHUYAMA
Existing dyke
NEW BRIDGE PILES
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20. 4- Ahuyama branch hydraulics
Another aspect to determine the effect of the area is the influence of the tributaries that reach the Magdalena River, in this case the Caño Ahuyama. Evaluation of Tr=100 year discharge was analized in respect of the existing dyke.
Two scenarios were analized:
-The first one contemplates high levels in the Magdalena river that generate flow towards the Ahuyama branch,
- The second one when the Ahuyama branch flows to the Magdalena river because of the runoff from the urban zone.
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21. 4- Ahuyama branch hydraulics
Scenario - 1
Flow DIrection
Projected Piles
CAÑO AHUYAMA
2.92 masl
2.87 masl
Dyke Projection
MAGDALENA RIVER
Q=20 m3/s
Projected Piles
Flow Direction
MAGDALENA RIVER
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22. 4- Ahuyama branch hydraulics
Scenario - 2
Flow Direction
MAGDALENA RIVER
CAÑO AHUYAMA
Projected piles
3.13 masl
3.43 masl
Q=55.05 m3/s
2.92 masl
Dyke Projection
The most critical condition to evaluate the water levels next to the Ahuyama branch is the Scenario 2.
As for the effect of the piles on the Ahuyama branch, this is minimal with over elevations of only 1cm.
It is recommended that the existing dyke be raised up to 3.5 masl along its entire length (300 m).
Q=98.4 m3/s
Q=20 m3/s
MAGDALENA RIVER
Projected piles
Flow Direction
Q=55.05 m3/s
Q=98.4 m3/s
Tr 25 años
Tr 2 años
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23. CONCLUSIONS
The evaluations performed for each of the mentioned scenarios were carried out using a free computational tool in 1 dimension (HEC-RAS). This software was sufficient to estimate levels and affectations in the study areas.
The determination of flood levels for the Canchera School, allowed to have the respective levels from which the new area to be built was projected and thus to avoid damages of floods.
In the same way, the modeling made it possible to dimension hydraulic structures such as the Pasadena channel and the dyke along the Ahuyama channel in the right bank.
The incidence of the New Bridge in the hydraulic conditions of the area, does not generate a considerable affectation in the water levels and the speeds in the sector in spite of flowing through 362 piles. This is due that most of the piles are in zones near to the banks, where the speeds are smaller than those registered in the center of the main channel.
The scour is limited by the coral rock, which is approximately 10 m below the natural bed.
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24. Source: Giovanny Escudero – El Heraldo 16 de Noviembre de 2016
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