4.1 Structural plate structures function structurally as a flexible ring that is supported by and interacts with the compacted surrounding soil. The soil placed around the structure is thus an integral part of the structural system. It is therefore important to ensure that the soil structure is made up of acceptable material and is well constructed. Field verification of soil structure acceptability using Test Methods D1556, D2167, D6938, or D2937, as applicable, and comparing the results with either Test Methods D698 or D1557, in accordance with the specifications for each project, is the most common basis for installation of an acceptable structure. Depending on the backfill used, other qualitative or performance-based methods acceptable to the engineer may also be used. The required density and method of measurement are not specified by this practice, but must be established in the specifications for each project.

4.2 Structural plate structures are also occasionally used in alternative applications not requiring soil-structure interaction for support. Depending on the application the structure may provide temporary or permanent support, confinement, concealment, shielding, or other functions not related to soil-structure interaction. The nature of support required, design requirements, and proper sizing of the structure will be determined by a project design engineer and is not part of the scope of this standard.

1.1 This practice primarily covers procedures, soils, and soil placement for the proper installation of corrugated steel structural plate pipe, pipe-arches, arches, and underpasses produced to Specification A761/A761M, in either trench or embankment installations. This practice also covers installation of structural plate for alternative uses that do not involve backfilling or soil-structure interaction.

1.2 A typical trench installation and a typical embankment (projection) installation are shown in Figs. 1 and 2, respectively. Structural plate structures as described herein are those structures factory fabricated in plate form and bolted together on site to provide the required shape, size, and length of structure. This practice applies to structures designed in accordance with Practice A796/A796M.

FIG. 1 Typical Trench Installation

FIG. 2 Typical Embankment (Projection) Installation

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.

1.3.1 SI units are shown in brackets in the text for clarity, but they are the applicable values when the installation is to be performed using SI units.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.