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Where a pipe is required as part of an embankment construction, it may be installed by compacting layers of fill uniformly on either side. It is important to bring the layers up uniformly on either side of the pipe. After a sufficient layer is compacted over the top of the pipe, ordinary embankment construction may […]

Underground structures may be built by a variety of means including embankment construction, open-trench construction, jacking, tunneling, and microtunneling. The proper design and installation of the foundation, bedding, and backfill for embankment and trench installations are critical to the performance of underground structures. They are also essential factors for achieving an accurate structural analysis of […]

For a waterway crossing, the designer must consider the backwater elevation and flow velocity for both the proposed and existing structures. It is recommended that the same hydraulic model be utilized for both the existing and proposed structure. Any increase in backwater elevation or stream velocity must be thoroughly analyzed and the upstream and downstream […]

Almost any size and shape of culvert can be utilized for the replacement of an existing bridge. However, reinforced concrete three — and four-sided box culverts, special shape reinforced concrete structures, metal box culverts, and long-span corrugated metal structures are particularly suited for this application. This is because they tend to have larger open-end areas […]

5.9.1 Introduction America’s transportation infrastructure—particularly the Interstate Highway System— is past its original anticipated design life and its age is showing. The age of the system coupled with high user demand and limited financial resources requires innovative thinking from the design engineer. One solution frequently utilized is the replacement of deficient bridges with prefabricated structures. […]

Steel tunnel liner plate and steel rib and lagging are flexible structures placed by a tunneling operation. Like other flexible structures, they are designed to deflect verti­cally under load so that the lateral side pressure will be established and essentially uniform radial pressure will develop about the perimeter of the structure. Because these structures are […]

Deflection of flexible pipes is not a design criterion in most specifications, because if pipes are properly installed with approved soil and compaction level, deflections will be within normal limits. However, the deflection for given loading and backfill conditions can be approximated for a round pipe. The traditional method of predicting deflection is the Iowa […]

Introduction. Gravity flow thermoplastic pipes used in highway drainage applications are typically manufactured of high-density polyethylene (HDPE) or polyvinyl chloride (PVC). To a lesser extent acrylonitrile-butadiene-styrene (ABS) pipe is also used but is limited to drain, waste, and vent applications. Plastic pipes are always circular in cross­section. They may be either of a solid wall […]

Introduction. Corrugated metal structures are typically manufactured of either steel or aluminum. These structures are generally designed for ring thrust by a semiempirical method that includes checks for wall area, buckling, and seam strength. A check is also FIGURE 5.39 Coefficients for calculating moment (M), thrust (N), and shear (V) in concrete pipe under linear […]

Introduction. There are two general types of rigid underground structures—those with a curvilinear shape, and those made up of straight walls and flat slabs. A reinforced concrete pipe is an example of the former, while a reinforced concrete box is an example of the latter. Rigid structures built in a curvilinear shape tend to act […]