DKA6B/C5306/dis2011/Deep Foundations For a Rail Bridge Replacement

Picture courtesy of callaac.com

A rail bridge replacement in sandpoint, Idaho, presented a host of challenges that resulted in a deep foundation solution. The site included difficult soft soils to great depths. Train traffic had to be maintained during construction, and there were site and permitting constraints. The 4,800 ft long railroad bridge spans Lake Pend Oreille in the Idaho Panhandle, providing an essential commerce link between the pacific Northwest and Chicago. Thus dictated that the bridge be replaced under live track conditions.

Originally built by Northern Pacific Railway as part of the first northern transcontinental railroad, the bridge was founded on timber piles driven to about 50 ft, supporting a concrete pier and spaced 50 ft for most of the length of the bridge. Portion of the bridge were replaced in the late 1950s or early 1960s. Replacement piers were supported on 90 ft pipe piles. By 2008, the bridge was functioning past the originally intended service life, and track maintainance across the bridge had become an increasing nuisance. Several of the existing piers had settled and rotated, causing track problems for the high speed freight trains.

"Courtesy of Deep Foundation Institute"

The site issues arised within the actual site condition are as follows:
 -Lake Pend Oreille is filled with more than 300 ft of soft silty clay. Beneath the clay lies a deposit of sand that becomes denser with increasing depth.
-The clays are soft, exhibiting low shear strength, and are highly compressible.
-Their residual shear strength is much less than the peak shear strength.
-Foundations bearing in the sand will have excellent load/settlement behaviour.

As an engineer of Geo-Penalistrik Consultant:
-Give your own general opinion on project constructability.
-Suggest a specific pile that can be used for the project.
-Explain to the client on construction method without bothering actual train traffic.

p/s: Submission due date 13 March 2012

Prelude to "Penalistrik"

Assalamualaikum and a very good day. Welcome to my brand new blog named "Penalistrik". It's my pleasure to introduce a brand new platform that specifically play an important role to share knowledge on civil engineering field. The blog been produced to provide an alternative method of online blogging interaction between both lecturer and students.

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