Post on 13-Apr-2016
description
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Self‐Hardening Slurry Wall Installation by Hydromill
at the Herbert Hoover Dike ‐An Innovative Solution
Mario Mauro
TREVIICOS ‐ 38 Third Ave. ‐ Charlestown, MA 02129 ‐ Ph: 617 – 241 4800 – www.treviicos.com
US Army Corps of Engineers – Jacksonville District
Florida DEP
South Florida Water Management District
Deep Foundation Institute
Acknowledgments
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1. Project Background
2. Selection of Cutoff Wall Construction Method
3. Quality Control & Validation
4. Conclusions
Outline of the Presentation
1.Project Background
• Originally constructed by farmers in theearly 1900’s for flood protection
• Two severe hurricanes in the late 1920’scaused massive flooding and loss of life
• The levee system was upgraded in the1930’s
• The levee system was upgraded againafter two more severe hurricanes in the1940’s, for a total of 143 miles.
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Herbert Hoover Dike Construction
• Through the years, the dike has experienced a high degree of seepage under and through the embankment, which could cause a failure of the system
• In 2007 USACE placed HHD on DSAC 1 list of dams with highest priority for action
• Priority Area is Reach 1, 22 mile stretch from Belle Glade to Port Mayaca
Courtesy of USACE
HHD in recent years
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Rehabilitation Concept
Courtesy of USACE
2. Selection of CW Construction Method
IDIQ Contract and performance based specifications
Contractor allowed to select wall installation method provided performance specifications requirements and acceptance criteria were met
Method selected had to be proved in a 500‐ft long demonstration section
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Previous Experience at HH Dike
Factors That Influenced the Selection of Cutoff Wall Construction Method
Variable nature of the ground and rock conditions
Depth of cutoff wall to 80 feet
Need for a reliable wall construction method
Strict acceptance criteria
Need for removal all peat and organic materials along the wall alignment
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Cutoff Construction Approach
Panel construction utilizing Self‐Hardening Slurry (SHS)
SHS is a mixture of water, cementitious material, bentonite and additives
SHS provides support of the open trench during excavation, and later becomes the permanent wall material
Hydraulic and mechanical clamshells to completely remove upper soils including peat, topsoil and miscellaneous fill material
Followed by a Hydromill cutter to excavate to a final depth of about 80 feet through limestone of variable continuity and hardness
SHS Cutoff Wall by Panel Method
• Continuous cutoff wall withoverlapping primary andsecondary panels
• Secondary panels providepartial overlap on each side of theadjacent primary panels ensuringwall continuity.
• Panel verticality is measured inreal‐time during excavation. Ifexcessive deviation occurs, thepanel verticality is corrected.
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Hydromill System
Desanding Equipment
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Use of the Hydromill with SHS
No previous experience in the US market
Standard Hydromill equipment is not designed for the use with self‐hardening slurry
Wear and tear on the equipment is a challenge, which requires attention
“Desanding” of SHS requires modifications of the standard desanding equipment
Self‐Hardening Slurry (SHS) Plant
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Work Platform and Site Access
Guide Wall Installation
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Clamshell Excavation under SHS
Excavation Equipment
Hydraulic clamshell Mechanical clamshell
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Hydromill Equipment
Hydromill Excavation under SHS
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SHS Cutoff Wall Construction
3. QC Control & Validation
Construction QA / QC testing
Panel verticality (real time monitoring via inclinometer in Hydromill)
Panel width (ea 100 ft) and depth (ea 20 ft) measurements
Panel centerline, locations, joints via GPS
Slurry plant samples (temperature, unit weight, viscosity, UCS and laboratory permeability)
Wet slurry grab samples at three depths (35, 55, 70/75 feet) of wall at 200 foot intervals hardened properties at 7 and 28 days (UCS, laboratory permeability)
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SHS Cutoff Wall ValidationVerification borings: @ 170 /200 ft
Borehole televiewer with inclinometer
In‐situ permeability: <1x10‐6
cm/sec
Strength: 100 psi min to 500 psi max (for 10‐point moving ave.) with no value below 75 psi
Homogeneous and continuous wall
Typical Core Sample
Borehole Televiewer
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In‐situ Permeability (Task Order 3)
1.0E‐10
1.0E‐09
1.0E‐08
1.0E‐07
1.0E‐06
1.0E‐05
Apr‐09 Jun‐09 Jul‐09 Sep‐09 Oct‐09 Dec‐09 Jan‐10 Mar‐10 Apr‐10
Perm
eab
ility (cm
/sec)
CW Acceptance Criteria: In situ permeability lower than 1 x 10‐6
cm/sec
Permeability Lab Testing – Post Placement Samples (Task Order 3)
1.0E‐10
1.0E‐09
1.0E‐08
1.0E‐07
1.0E‐06
1.0E‐05
May‐09 Jun‐09 Jul‐09 Jul‐09 Aug‐09 Sep‐09 Oct‐09 Nov‐09 Dec‐09 Jan‐10 Feb‐10 Mar‐10 Apr‐10
Perm
eab
ility (cm
/sec)
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Strength Testing (UCS) – Panel Joint
UCS testing of Panel Joint (VB‐3)Core Specimen at Panel Joint (VB‐2, 58 ft depth)
Exposed Lakeside of Cutoff WallExposed Top of Cutoff Wall
Visual Inspection of Top of Cutoff Wall
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Performance specifications were the right approach for this project
The innovative use of the Hydromill cutter allowed successfulconstruction of the SHS cutoff wall through heterogeneous materialsand rock (over 7.2 miles, 2.5 M sqft of wall)
The Clamshell/Hydromill SHS construction method provided a cut‐off wall that is homogeneous, continuous and meets strength andpermeability performance criteria
Carefully designed self‐hardening slurry produced good bondingbetween primary and secondary panels and prevented desiccationand cracking of the top of the hardened wall
The hard work and dedication of all TREVIICOS personnel was key tosuccess.
4. Conclusions
TREVIICOS ‐ 38 Third Ave. ‐ Charlestown, MA 02129 ‐ Ph: 617 – 241 4800 – www.treviicos.com