Hydrodynamic Performance and Design Evolution of Wedge-Shaped Blocks for Dam Protection against Overtopping
Abstract
:1. Introduction and Background
2. Materials and Methods
2.1. Experimental Facility
- Measuring devices for water levels and discharge of skimming and seepage flows:
- Electromagnetic flowmeter to measure the pumped flow rate.
- Triangular thin-plate weir to measure the flow that leaks through the open joints between adjacent blocks and seeps through the granular layer.
- Electromagnetic limnimeters (4) for measuring the water level at the following points: the inlet tank, the upstream end of the chute, the abovementioned triangular thin-plate weir and the rectangular thin-plate weir at the end of the stilling basin.
- Pressure measurement system to register the water pressures at several points on the block tread, base and the riser step of the WSBs [27], formed by:
- A set of 12 Messtech submersible XA-700 pressure transducers connected to measuring tubes installed on one of the measuring blocks.
- A pressure gauge (Scanivalve DSA3207 Corp. model) with 12 sockets measuring tubes installed on a second measuring block.
2.2. Flow Test Characterization
2.2.1. Flow Regimes
2.2.2. Inception Point
2.2.3. Uniform Flow Area
2.3. Testing Program
3. Results and Discussion
3.1. Hydrodynamic Pressures
3.1.1. Pressures on the Block Tread
Armorwedge™ Block (w1) Tests with Free Draining Conditions (d1)
Effect of Drainage Layer (d2) on ArmorwedgeTM Block (w1)
Comparison of the ArmorwedgeTM (w1) and ACUÑA (w2) Blocks
Effect of Sealing Joints between Blocks
3.1.2. Pressures on the Block Riser
3.1.3. Pressures on the Base of the Block
ArmorwedgeTM Block (w1) Tests in Free Draining Scenario (d1)
Comparison of the ArmorwedgeTM (w1) and ACUÑA (w2) Blocks
3.2. Hydrodynamic Forces on the WSBs
3.3. Drainage Flow
3.4. Effect of the Joints among WSBs on the Drainage Flow
4. Conclusions
- Hydrodynamic pressures on the blocks tread were similar for the ArmorwedgeTM and ACUÑA blocks, although a slightly higher pressure was observed on the ACUÑA block for the highest discharge flows in the lower part of the chute. Although a limited effect, this is favorable for the stability of the block.
- Pressure records in the riser of the ACUÑA block were negative or close to zero, with the greatest suction located in the upper third of the riser. This fact was also previously observed by numerical modeling and led to the new WSB design, ACUÑA, with air vents in the upper part of the riser.
- Negative suction pressures were registered at the base of the two types of blocks when the drainage layer was not saturated. This is favorable for the stability of the block. The suction at the base was higher when the longitudinal joints between blocks were sealed. The effect of sealing just the upper part of the chute was remarkable. The leakage towards the drainage layer was significantly reduced, delaying or avoiding its saturation and, hence, the uplift force.
- The drainage flow rate increased significantly with the inlet discharge flow when the drainage layer was not saturated; however, it (expressed as a fraction of the inlet flow) decreased with inlet flow if the drainage layer was saturated.
- It should be noted that in some cases, positive pressures, although low, were detected in the lower part of the riser. In these cases, the air vents presumably allowed the water to enter the drainage layer if air vents were located at the base of the riser, as was the case for the ArmorwedgeTM block.
- In the upper part of the channel, the hydrodynamic stabilizing force increased systematically with the discharge flow. The ACUÑA block was more stable than the ArmorwedgeTM block for all the tested cases. In the lower part of the channel, the stabilizing force was reduced with the discharge flow due to the saturation of the drainage layer and uplift pressures appearing at the base of the block. In this situation, the ArmorwedgeTM block was more stable than the ACUÑA block.
- When the joints between blocks were sealed, and the drainage layer was unsaturated, the stabilizing forces increased with the discharge flow, and the ACUÑA block was more stable than the ArmorwedgeTM block for all cases with the skimming flow regime.
- In both WSBs, the longitudinal joints between blocks were the source of the highest percentage of the total leakage flow. In addition, these leaks came mostly from the upper area of the flume.
- Although joint sealing is not a usual practice, it is advisable to consider the benefits and implement a cost-effective way for sealing the joints in new WSB dam protection against overtopping or spillways, especially in the upper sections.
5. Patents
Supplementary Materials
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Nomenclature
Cu | uniformity coefficient |
d1 | free drainage condition |
d2 | the granular layer drainage condition |
D10 | size of which 10% of the particles, in weight, are finer (m) |
D50 | size of which 50% of the particles, in weight, are finer (m) |
F* | roughness Froude number |
hc | critical depth |
hs | height of the block riser |
Li | longitudinal distance between the critical depth position on the crest of the dam and the horizontal face where the inception point is located |
Lu | longitudinal position from the dam or flume crest of the beginning of the quasi-uniform region |
l | the partially exposed length of the top surface of the block |
ls | the total exposed length of the top surface of the block |
L′ | partial length of the base of the block |
L′b | the total length of the base of the block |
p | average hydrodynamic pressure |
q | flow-rate inlet in the chute |
qd | drainage flow-rate |
w1 | ArmorwedgeTM block |
w2 | ACUÑA block |
x | coordinate horizontal to the crest of the dam |
y | coordinate perpendicular to the crest of the dam |
γ | water volumic weight |
θ | the angle of the slope of the chute |
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h′ (hc hs−1) | 4.51 | 3.99 | 3.44 | 2.84 | 2.52 | 2.17 | 1.37 |
q (m2 s−1) | 0.24 | 0.20 | 0.16 | 0.12 | 0.10 | 0.08 | 0.04 |
Flow Rate q (m2 s−1) | H′ (hc hs−1) | Row Number | Distance of the Inception Point Li | |||
---|---|---|---|---|---|---|
Observed | Observed Interval | Relvas [18] | Chanson [43] | Matos [44] | ||
0.04 | 1.37 | 3 | 673–880 | 779 | 684 | 617 |
0.08 | 2.17 | 4–5 | 1035–1293 | 1283 | 1121 | 1035 |
0.10 | 2.52 | 5–6 | 1190–1500 | 1507 | 1314 | 1223 |
0.12 | 2.84 | 6 | 1293–1500 | 1718 | 1496 | 1401 |
0.16 | 3.44 | 6–7 | 1293–1707 | 2114 | 1837 | 1737 |
0.20 | 3.99 | 7–8 | 1500–1914 | 2482 | 2154 | 2053 |
0.24 | 4.51 | 9–10 | 1914–2328 | 2831 | 2453 | 2352 |
Flow Rate q (m2 s−1) | h′ (hc hs−1) | Uniform Flow Depth Location (m) | |||||
---|---|---|---|---|---|---|---|
CIRIA Guide Hewlett et al. [3] | Boes and Minor [48] | Relvas [18] | |||||
Distance (m) | Row | Distance (m) | Row | Distance (m) | Row | ||
0.04 | 1.37 | 1.09 | 5 | 1.83 | 8 | 1.56 | 7 |
0.08 | 2.17 | 1.73 | 8 | 2.91 | 13 | 2.57 | 12 |
0.10 | 2.52 | 2.01 | 9 | 3.38 | 16 | 3.01 | 14 |
0.12 | 2.84 | 2.27 | 10 | 3.81 | 18 | 3.44 | 16 |
0.16 | 3.44 | 2.75 | 13 | 4.62 | 22 | 4.23 | 20 |
0.20 | 3.99 | 3.20 | 15 | 5.36 | 25 | 4.96 | 23 |
0.24 | 4.51 | 3.61 | 17 | 6.05 | 28 | 5.66 | 27 |
WSB | Drainage Conditions | q (m2 s−1) | Measured Variables | Joints and Air Vents Conditions | Number of Tests Performed |
---|---|---|---|---|---|
w1 | d1 | 0.04–0.24 | P on rows 5 and 25/L | Without sealing | 3 |
P on rows 10 and 30/L | Without sealing | 2 | |||
P on rows 15 and 35/L | Without sealing | 2 | |||
P on rows 15 and 43/L | Without sealing | 1 | |||
L | Without sealing | 1 | |||
L | LJ sealing | 1 | |||
L | LJ and TJ sealing | 1 | |||
w2 | d1 | 0.04–0.24 | L | Without sealing | 1 |
LJ sealing | 1 | ||||
LJ and TJ sealing | 1 | ||||
d2 | 0.04–0.20 | P on rows 10 and 25/L | Without sealing | 2 | |
LJ sealing | 2 | ||||
LJ and TJ sealing | 2 | ||||
w1 | d2 | 0.04–0.20 | P on rows 10 and 25/L | Without sealing | 1 |
LJ sealing | 1 | ||||
LJ and TJ sealing | 1 | ||||
w2 | d2 | 0.04–0.20 | L | Without sealing | 1 |
LJ and TJ sealing of rows 1 to 8. | 1 | ||||
LJ/TJ/AV sealing of rows 1 to 8. | 1 | ||||
LJ and TJ sealing of rows 1 to 16. | 1 | ||||
LJ/TJ/AV sealing of rows 1 to 16. | 1 | ||||
LJ and TJ sealing of rows 1 to 24. | 1 | ||||
LJ/TJ/AV sealing of rows 1 to 24. | 1 | ||||
LJ and TJ sealing of rows 1 to 32. | 1 | ||||
LJ/TJ/AV sealing of rows 1 to 32. | 1 |
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Caballero, F.J.; Toledo, M.Á.; Moran, R.; San Mauro, J. Hydrodynamic Performance and Design Evolution of Wedge-Shaped Blocks for Dam Protection against Overtopping. Water 2021, 13, 1665. https://doi.org/10.3390/w13121665
Caballero FJ, Toledo MÁ, Moran R, San Mauro J. Hydrodynamic Performance and Design Evolution of Wedge-Shaped Blocks for Dam Protection against Overtopping. Water. 2021; 13(12):1665. https://doi.org/10.3390/w13121665
Chicago/Turabian StyleCaballero, Francisco Javier, Miguel Ángel Toledo, Rafael Moran, and Javier San Mauro. 2021. "Hydrodynamic Performance and Design Evolution of Wedge-Shaped Blocks for Dam Protection against Overtopping" Water 13, no. 12: 1665. https://doi.org/10.3390/w13121665