kinzua bridge micropiles case history

Mi il f R h bilit ti fMicropiles for Rehabilitation of the Kinzua Viaduct

Jonathan Bennett, PE, D.GE – Chief EngineerEarth Support DivisionSeptember 22, 2010

PRESENTATION OVERVIEW• Built in the late 1800’s, The Kinzua Viaduct in Mt. Jewett, PA was once the 

tallest railroad bridge in the world. • In 2003, the viaduct was partially destroyed by a tornado. Supplemental 

uplift resistance was needed for the Viaduct’s tower piers in order to rehabilitate the remaining structure and convert it into a working sky walkrehabilitate the remaining structure and convert it into a working sky walk observation deck. 

• Tension micropiles were selected to provide this uplift resistance. There were a number of challenges that had to be overcome for successfulwere a number of challenges that had to be overcome for successful implementation. This case history tells the story…

PRESENTATION OUTLINE

• Brief History of Kinzua Viaduct• Destruction of Viaduct in 2003• Structure Rehabilitation and Conversion• Micropiles for Rehabilitation of Tower Piers• Micropiles for Rehabilitation of Tower Piers• Design Details• Discussion of Major Issues• Installation and Testing

Project LocationKinzua Bridge State Parkg

Hamlin Township – McKean County – near Mt. Jewett, PA

ErieErie

PittsburgPittsburg

Harrisburg

HistoryHistory

• Built in 1882 by the Phoenixville Bridge WorksBuilt in 1882 by the Phoenixville Bridge Works Company, the Kinzua Viaduct was the highest railroad bridge in the world. It was constructed as gan alternate to laying an additional eight miles of track over rough terrain along the line leading to McKean County’s coal, timber and oil lands.

• Built of iron, the original viaduct was 301 feet ghigh, 2,053 feet long, and weighed 3,105,000 pounds.

HistoryHistory

HistoryHistory

• By 1900 it became necessary to rebuild theBy 1900, it became necessary to rebuild the entire structure with steel to accommodate heavier trainsheavier trains.

• In May of 1900, about 100 to 150 men working ten hour days completed the job inworking ten hour days completed the job in 105 days. The new steel viaduct had the same measurements but now weighed 6 715 000measurements but now weighed 6,715,000 pounds (approximately twice the original).

HistoryHistory

HistoryHistory

• Freight traffic on the bridge was discontinued inFreight traffic on the bridge was discontinued in June of 1959.

• In 1963 Governor William Scranton signed a lawIn 1963, Governor William Scranton signed a law creating the Kinzua Bridge State Park.

• The bridge was placed on the National Register of• The bridge was placed on the National Register of Historic Civil Engineering Landmarks in 1977.

• The Knox and Kane Railroad offered excursion• The Knox and Kane Railroad offered excursion trips across the bridge until June of 2002 when it was closed for restorationwas closed for restoration.

HistoryHistory

HistoryHistory

• Beginning in February 2003, W.M. Brode Co.Beginning in February 2003, W.M. Brode Co. of Newcomerstown, OH began working to perform repairs on the Kinzua Viaduct.

• On Monday July 21, 2003 at approximately 3:15PM, an F1 tornado (wind speed 73‐112 mph) struck the side of the Viaduct. Eleven towers from the center of the bridge were 

f h i i d ll d htorn from their piers and collapsed onto the valley floor.

HistoryHistory

Post‐Collapse RehabilitationPost Collapse Rehabilitation

The Pennsylvania Department of ConservationThe Pennsylvania Department of Conservation and Natural Resources formed a design team and solicited bids to renovate the remainingand solicited bids to renovate the remaining towers and construct a sky walk observation 

deck The construction project was awarded todeck. The construction project was awarded to J.D. Eckman, Inc. of Atglen, PA in 2009. 

Post‐Collapse RehabilitationPost Collapse Rehabilitation

Project TeamProject Team

• Owner – Pennsylvania Department ofOwner  Pennsylvania Department of Conservation and Natural Resources (DCNR)

• Geotechnical Engineer GeoMechanics Inc• Geotechnical Engineer – GeoMechanics, Inc.• Structural Engineer – HRG• Prime Contractor – J.D. Eckman, Inc.• Micropile Contractor – GeoConstructors, Inc.p ,

Micropile SelectionMicropile Selection

Micropile pier anchors were selected to provideMicropile pier anchors were selected to provide supplemental uplift resistance and protection for the existing piers from excessive loadingfor the existing piers from excessive loading. Micropiles were the ideal approach for this project due to limited access installation theproject due to limited access installation, the requirement for tensile load resistance, and installation through existing foundationinstallation through existing foundation 

elements.

Scope of WorkScope of Work

• Core Drilling Through Existing Stone PiersCore Drilling Through Existing Stone Piers• Micropile and Secondary Anchor Installation

f i f i il• Proof Testing of Micropiles• Construction of Anchorage Assembly (by J.D. Eckman)

• Lockoff of Micropile Tension Loadp

Construction ChallengesConstruction Challenges

• Site and Pier AccessSite and Pier Access• Material HandlingCl ( 0”) i l illi Cl• Close (10”) Horizontal Drilling Clearance

• Water for Grout Mixing• Cold Weather Concerns• Drilling Through Existing Sandstone PiersDrilling Through Existing Sandstone Piers

Site and Pier AccessSite and Pier Access

Woody Allen says that “Eighty percent of success is showing up ”success is showing up…

In this case, getting the drilling and grouting equipment where it needed to be was eighty 

percent of the job…

Site and Pier AccessSite and Pier Access

Site and Pier AccessSite and Pier Access

Site and Pier AccessSite and Pier Access

Site and Pier AccessSite and Pier Access

Site and Pier AccessSite and Pier Access

Site and Pier AccessSite and Pier Access

Site and Pier AccessSite and Pier Access

Site and Pier AccessSite and Pier Access

Material HandlingMaterial Handling

With long full length micropile reinforcementWith long full length micropile reinforcement with partial encapsulation needing to be 

inserted in the drilled holes material handlinginserted in the drilled holes, material handling was almost as challenging as getting the drilling 

and grouting equipment in placeand grouting equipment in place.

Material HandlingMaterial Handling

Material HandlingMaterial Handling

Material HandlingMaterial Handling

Water for Grout MixingWater for Grout Mixing

Due to logistical issues with getting water to theDue to logistical issues with getting water to the site, onsite water from a cistern was used  The water was tested before and during use towater was tested before and during use to ensure that it was of sufficient quality to use 

for mixing groutfor mixing grout.

Water for Grout MixingWater for Grout Mixing

Cold Weather ConcernsCold Weather Concerns

With average temperatures during WinterWith average temperatures during Winter installation at approximately 20 F with lows of  ‐5 to ‐15 F precautions were taken with regard5 to  15 F, precautions were taken with regard to mixing and placing grout. A heated shack was constructed and heating was provided atwas constructed and heating was provided at 

the micropile locations as well.

Cold Weather ConcernsCold Weather Concerns

Drilling Through Existing PiersDrilling Through Existing Piers

The existing sandstone block piers are from theThe existing sandstone block piers are from the original bridge construction and have been encased in concrete shells We had the goodencased in concrete shells. We had the good fortune of having drawings of the pier block layouts from 1918 With rock drilling beinglayouts from 1918. With rock drilling being performed with a Down Hole Hammer, diamond core drilling was utilized to getdiamond core drilling was utilized to get 

through the piers so as to not risk damaging the piers with the DHHthe piers with the DHH.

Drilling Through Existing PiersDrilling Through Existing Piers

Drilling Through Existing PiersDrilling Through Existing Piers

Pier after jacket removal

Drilling Through Existing PiersDrilling Through Existing Piers

Drilling Through Existing PiersDrilling Through Existing Piers

Drilling Through Existing PiersDrilling Through Existing Piers

Drilling Through Existing PiersDrilling Through Existing Piers

Installation & LockoffInstallation & Lockoff

• Removal of Concrete Jackets on Ex PiersRemoval of Concrete Jackets on Ex. Piers• Core Drilling for Micropiles

i il ll i• Micropile Installation• Replacing the Concrete Pier Jackets• Fabrication of Micropile Connection• Micropile Testing and Final LockoffMicropile Testing and Final Lockoff

Jacket RemovalJacket Removal

Jacket RemovalJacket Removal

Core DrillingCore Drilling

Micropile InstallationMicropile Installation

Jacket ReplacementJacket Replacement

Jacket ReplacementJacket Replacement

Connection FabricationConnection Fabrication

Connection FabricationConnection Fabrication

SummarySummary

• Tension micropiles were the ideal applicationTension micropiles were the ideal application for the Kinzua Viaduct Pier Rehabilitation. The characteristics of micropiles were a match for the requirements for the project application.

• Through teamwork, all of the construction challenges were able to be effectively overcome.

• All of the micropiles were successfully installed, tested and accepted by the Owner.

THANK YOU!for Your Time and Attention

You will be rewarded accordingly…

Sho ld o ha e f rther q estion onta t jbennett@ eostr t res omShould you have further question, contact jbennett@geostructures.com.