it appears that no thrust block
has been introduced to the upper 90 degree bend in the shaft.
The boundary condition of the bottom thrust block
represents a semi-rigid connection.
The work also involved retrofit welding restrained joints at a location where a thrust block
restraining a 90-degree bend would be eliminated to accommodate the construction of the new box culverts.
Even though the savings was only about $20,000, for us it meant we wouldn't have to sub out the welding." Since you can't go straight from concrete cylinder to ductile iron, there were some challenges at the valve chamber where they had to jack hammer away at the existing thrust block
and the concrete cylinder pipe to expose the steel cylinder.
The elbow was secured with a concrete thrust block
. Other manholes included a 10-ft diameter structure built with block and mortar, and two 8-ft diameter manholes that were modified by using a 60-in.
Moreover, thrust block
restraints are not required for most applications, which is a major cost factor with other piping systems."
The HPD system does not use a thrust block
or a ballast foundation.