Technical Manual: Conduits through Embankment Dams (FEMA 484)

Conduits through Embankment DamsFigure 63.—Longitudinal reinforcement acrossa conduit joint experienced tensile failurecaused by lateral spreading of theembankment dam.the conduit and for bending stresses due to nonuniform foundation conditions alongthe length of the conduit section. Figure 63 shows an example of longitudinalreinforcement that experienced tensile failure caused by lateral spreading of theembankment dam.Reclamation’s experience has shown that cracking in reinforced cast-in-placeconduits due to shrinkage and temperature can be minimized by placing conduits in12- to 16-foot sections (figure 64). The interfaces between conduit sections aretypically control joints. Control joints are used to provide for control of initialshrinkage stresses. Waterstops should be used across all control joints, and a bondbreaker, such as curing compound, should be applied to control the joint surfaces todirect cracking toward the joints. The longitudinal reinforcement is continuousacross the control joint to limit movement between adjoining ends of conduitsections. The conduit sections should be constructed in an alternating pattern, suchthat any concrete volume shrinkage occurs prior to adjoining conduit sections beingplaced. The preferred placement method for transverse sections of concrete in smallCt.JCt.JCt.JCt.J12 to 16 FeetFigure 64.—Concrete placement for a reinforced cast-in-place conduit.92