Lecture 31, 32, 33Temporary Earth Retaining StructuresJuly 29, 2009Meeting 11
CofferdamsTemporary Structures to keep out water and soil to permit construction in the dryTypesSheet Pile Wall with bracing (used for compact structures)Cellular cofferdams (used for large construction areas)
Typical Z Section Piling
Cofferdam Construction StepsPre-dredge to remove soft material and level area
Install temporary support pilesSet bracing frame and hang from temp piles
Drive Sheet Pile Wall using frame a guideExcavate bottom of cofferdamPlace concrete sealDewater and commence construction
Tremie PipeConcrete Seal
Compact CofferdamSteel Sheet PilesBracingConcrete Seal
Cellular CofferdamsMainCellConnecting Arc
Cellular CofferdamsUsed to dike off a large construction areasPractical to depths of 75 ft.Cells are filled with granular material
Cellular Cofferdam ConstructionFalsework ring templates must be usedGuide rings are temporarily supported by temporary pilesSheeting installation starts with the Y section.Pile layouts should be marked on the guide ringAfter Sheet piling is complete Cells are filled
Typical Flat Sheet Pile SectionsFabricated Y
Cofferdam Example
Cofferdam Detail
Other Earth Retaining Structures
Trench Boxes Prefabricated structure that is moved as the work progresses
Trench Box
Vertical Wood SheatingVertical woodsheatingTimber waleTimber cross bracing
Steel Soldier Piles and Horizontal SheatingHorizontal sheating set behind the flangeDriven sheet H piles
Braceless Systems Using Tie BacksTendonStressing UnitGrout
Tie back Example
Installing Tie backs
*
Top Related