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Advanced Technology for Cyclones Storm Damage Risk Reduction Systems and Flood
Protection Levees
Amir Shahkolahi
Global Synthetics, Brisbane, AustraliaE-mail: [email protected]
Drew Loizeaux
Propex, USAE-mail: [email protected]
Flood Protection Levees:OVERTOPPING OF THE L-550 LEVEE IN ATCHISON COUNTY, MISSOURI, DURING A MISSOURI RIVER FLOOD, JUNE 2011 (SOURCE: USACE).
Flood Protection Levees Armouring:• Armouring will increase resiliency against severe wave overtopping caused by
hurricane storm surges.
• Armouring will help reduce scour and protect the integrity of the flood defence structure when confronted with severe wave overtopping.
What is the best Armouring technique?
Armouring Types:• · Grass
• · Soil Cement Treatments
• · Erosion Control Blankets
• · Turn Reinforcement Mat
• · Rock Riprap
• · Gabions
• · Concrete Slope Paving
• · Open Stone Asphalt
• · Fabric Formed Concrete
• · Articulated Concrete Block (ACB)
Research Background:• In 2005: Cyclone/Hurricane Katrina,
Southeast Louisiana, Category 5.
• Approximately 80% of New Orleans was flooded.
• Flood depths exceeding 15 feet in many areas.
• Surge and waves caused 50 major levee
breaches
• Thirty-four of the city's pumping stations were
damaged,
• Rainfall: 14 inches in a 24-hour period.
• More than 1,500 lives were lost.
Research Background• In 2006: US Army Corps of Engineers (USACE) started the $14.5 Billion program,
“Hurricane and Storm Damage Risk Reduction System (HSDRRS)”
Focus:
Strengthening levees, floodwalls, gated structures and pump stations
Goal:
What is the most cost effective, environmentally friendly and high performance solution
Research Background• In 2005-2006: USACE used ArmrMax® Engineered Earth Armouring Solution
(EEAS) on Penn flood levee as the armouring system as a trial.
•What is ArmorMax® EEAS?
ArmorMax® Engineered Earth Armouring Solution (EEAS):
• Combination of:
Engineered Earth Anchors (EEA)
High Performance Turf Reinforcement Mat (HPTRM)
Research Background• In 2008:
Category 3 Cyclone, winds of 208 km/h
What happened to Penn levee
with ArmorMax® EEAS?
Research Background
• No damage and erosion occurred
• ArmorMax® EEAS could protect the levee
• As a results, USACE decided to investigate this system in details and in comparison to other systems
Research details:
Two phases:Phase 1: Full-scale field test: To investigate the requirements of HPTRMs to withstand installation and maintenance (e.g. mowing) loads
Phase 2: Full Scale Overtopping Test: To investigate the performance of these systems under real overtopping condition
Phase 1: Full-scale field test result• HPTRM minimum requirements:
Property Test Method Average Roll Value
Mass per unit area ASTM D6566 ≥ 288 g/m2
Thickness ASTM D6525 ≥ 7.6 mm
Light Penetration (% passing) ASTM D6567 ≤ 45%
Tensile Strength ASTM D6818 ≥ 45 kN/m
Elongation ASTM D6818 ≤ 65%
Resiliency ASTM D6524 ≥ 70%
UV Resistance @2500 hrs ASTM D4355 ≥ 80%
Phase 2: Full-scale Overtopping Test • Colorado State University (CSU)
• Can simulate average overtopping discharges as high as 370 l/s per m
HPTRM Opening/Light Penetration
HPTRMs with smaller percent light penetration (to a minimum necessary value) improved vegetation performance in hydraulic testing
Conclusion:• HPTRM reinforced vegetation systems perform as well as if not better than the rock
armour protection layers for hydraulic applications such as storm water channels and flood protection levees.
• A HPTRM solution is a more cost effective and environmentally friendly solution than traditional hard armour solutions.
• Engineered Earth Armouring Solution (EEAS) which consist of a High Performance Turf Reinforcement Mat (HPTRM) and Engineered Earth Anchors (EEAs) can increase the safety factor of the armouring system against hydraulic forces and also provide slope surface stability.
Conclusion:• Tensile strength is the key component for durability and long-term performance of
HPTRMs, especially for storm water and flood protection applications.
• FHWA minimum requirement for tensile strength of HPTRMs is 45 kN/m.
• UV resistance is another key parameter for the durability of HPTRMs.
• HPTRMs with smaller percent light penetration, improves the vegetation performance in hydraulic testing whether established from seed or turf.
• Light penetration of 10% as minimum and 50% as maximum is suggested for HPTRMs to provide the required short term and long-term performance.