11 th Annual Technical Forum GEOHAZARDS IMPACTING TRANSPORTATION IN - PowerPoint PPT Presentation

Filename and location 11 th Annual Technical Forum GEOHAZARDS IMPACTING TRANSPORTATION IN THE APPALACHIAN REGION GEO-DESIGN APPLICATIONS IN KARST ENVIRONMENTS William D. Spencer, P.G., Jaye Richardson, and Chris Ramsey, P.E. AMEC, Nashville TN August 3, 2011 1

Filename and location KARST CAN OCCUR ANYTIME AND ANYWHERE 2

Filename and location KARST CAN OCCUR ANYTIME AND ANYWHERE 3

Filename and location NSC Mainline Track at MP 96.1A Morristown, Tennessee 4

Filename and location NSC Mainline Track at MP 96.1A Morristown, Tennessee 5

Filename and location NSC Mainline Track at MP 96.1A Morristown, Tennessee 6

Filename and location NSC Mainline Track at MP 96.1A Morristown, Tennessee 7

Filename and location NSC Mainline Track at MP 96.1A Morristown, Tennessee SUMMARY OF DEEP FOUNDATION OPTIONS PERCEIVED PERCEIVED OPTIONS ADVANTAGES DISADVANTAGES • Driven Piles Impossible to assess bearing strata Low cost (H-Piles) • Drilled Piers High load High cost; potentially large voids in (Caissons) capacity; low long bedrock might take large quantities of term risk concrete to fill. • Small Diameter Low long-term risk; Moderate to high cost; smaller than Drilled Pipe easy to make “normal” pile size for bridge bents; Piles (Micro Piles) adjustments requires real-time field engineering during construction to adjust. 8

Filename and location NSC Mainline Track at MP 96.1A Morristown, Tennessee AFTER BEFORE Micro pile and structural land bridge Karst engulfing the soil and ballast REMOVES the karst from play and provides for surface drainage under the track. 9

Filename and location Mack Hatcher Parkway Franklin, Tennessee 10

Filename and location Mack Hatcher Parkway Franklin, Tennessee 11

Filename and location Mack Hatcher Parkway Franklin, Tennessee 12

Filename and location Mack Hatcher Parkway Franklin, Tennessee 13

Filename and location Mack Hatcher Parkway Franklin, Tennessee 14

Filename and location Mack Hatcher Parkway Franklin, Tennessee 15

Filename and location Mack Hatcher Parkway Franklin, Tennessee 16

Filename and location Mack Hatcher Parkway Franklin, Tennessee 17

Filename and location Mack Hatcher Parkway Franklin, Tennessee 18

Filename and location Mack Hatcher Parkway Franklin, Tennessee SO HOW DO WE BUILD A BRIDGE FOUNDATION ON EXTREMELY KARSTIC AND VARIABLY BEDROCK?? BY A COMBINATION OF INTEGRAL ABUTMENTS, SPREAD FOOTINGS, WHERE POSSIBLE, AND MICROPILES 19

Filename and location Mack Hatcher Parkway Franklin, Tennessee WHY ? CAISSONS ARE DIFFICULT TO INSTALL IN IRREGULAR BEDROCK CONDITIONS THEY ARE COSTLY $$ HOW MUCH ADDITIONAL CONCRETE WILL BE USED TO FILL THE OPEN CAVITIES? HOW MUCH DOES IT COST TO USE PERMANENT CASING IN THE GROUND TO CONTROL CONCRETE PLACEMENT? 20

Filename and location Mack Hatcher Parkway Franklin, Tennessee HOW CLOSE IS THAT END BEARING H-PILE TO THE WEATHERED ROCK OR OPEN CAVITY? WE DON’T KNOW 21

Filename and location Micro-piles as a SOLUTION 22

Filename and location RECENT LOAD TESTING ON INSTALLED MICRO-PILES DESIGN LOADS WERE 300 KIPS COMPRESSION AND 180 KIPS TENSION COMPRESSION LOADING EXCEEDED 200% OR 600 KIPS TENSION LOADING FAILED AT 200% OR 360 KIPS DUE TO FOLIATION OF WEATHERED ROCK FOLLOW-UP LOAD TESTING EXCEEDED 200% OF DESIGN FOR TENSION AND COMPRESSION 23

Filename and location QUESTIONS?? 24

Filename and location THANK-YOU 25