June 1983 - Maritime Reporter and Engineering News

Philadelphia Resins System Solves Alignment Problems On World's Largest Movable Flood Barrier

To protect more than a million Londoners and an estimated $8- billion worth of property, the world's largest movable flood barrier has been put into operation on the River Thames, eight miles downstream from Parliament Square.

The entire island of England, Scotland, and Wales is tilting into the sea, with the southeast corner — where London is located — leading the way. London is also sinking a foot per century into its bed of clay. To further compound this potentially catastrophic problem, melting of the polar ice caps has raised the tide level in the Thames by 2V> feet (760 mm) during the past 100 years.

Surge tides, which result from a combination of meteorological conditions in the North Sea, have p e r i o d i c a l l y caused numerous deaths along the Thames. In 1953, flooding of the Thames Estauary claimed 300 lives.

To exclude surge tides from the upper estuary, a 1,760-foot (520-meter) barrier, consisting of 10 separate movable steel gates, was put into service last winter after almost nine years of construction and more than a quarter century of planning. Conceived and designed by Rendel Palmer and Tritton, as consulting and supervising engineers for The Greater London Council, the Thames Barrier is now owned and operated by the council.

If a dangerously high tidal surge threatens, six main flood gates -— fabricated from heavy steel plate—are swung up 90 degrees from the riverbed to form a continuous barrier, together with four subsidiary gates which are lowered into place facing downstream to stem the tide. In normal times, each main gate rests within a concrete sill in the riverbed to allow free passage of shipping through the pier openings.

It takes no more than a half hour to raise or lower the flood barrier.

The main gates were transported to the site by barge in three sections. Each end section was bolted to the pivot shafts on each pier onto which the main span was bolted. The bolted joints called for extreme accuracy which could not be obtained by machining although many attempts were made. After comprehensive tests to satisfy the overseeing consultants, these heavily stressed joints were made true by the use of special epoxy resin compounds manufactured by Philadelphia Resins Corporation of Montgomeryville, Pa. These special epoxy resins are known as Chockfast systems.

The huge gates are operated by massive hydraulic rams, which have to be lined up very accurately to their pivoted connections in order to turn the gates.

The Chockfast epoxy resins were used to align and support every gate component and the operating machinery.

The design engineering services and the installation of the forty-one tons of Chockfast were handled by Industramar Limited, High Wycombe, Bucks, England, one of Philadelphia Resins' worldwide teams of chocking special- ists. The contribution of Industramar and Philadelphia Resins' Chockfast systems were hailed in a leading British civil engineering journal as one of the "unsung success stories of the River Thames Barrier Project." For free literature on the Chockfast systems, Write 60 on Reader Service Card

Other stories from June 1983 issue


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