scope:

Overview

This standard sets out practices that are needed to produce geotechnically stable and resilient engineered fill for projects where the engineered fill will provide a foundation for lightweight structures.

The geotechnical designer shall assess whether it is appropriate to use this standard for each project.

Inclusions

This standard covers engineered fill construction for lightweight structures such as:

(a) Residential building development undertaken in accordance with NZS 3604, or other developments with similar foundation loadings and sensitivity to ground settlement;

(b) Commercial building developments with foundation loads and performance expectations similar to what is described in (a) above.

This standard is appropriate for the placement of fill associated with the following structure types, where these structures are being constructed for the purposes described above:

(c) Mechanically stabilised earth (MSE) slopes with a face inclined at less than 60º from the horizontal;

(d) Retaining walls (excluding drainage media and services).

C1.1.2

To assess if this standard is suitable for use with a proposed development, the geotechnical designer should carefully consider whether the unfactored bearing stress applied to the ground will be similar to or less than a light timber-framed (with lightweight wall and roof cladding) residential three-storey building. The geotechnical designer should assess the sensitivity of the proposed structure(s) to settlement or deformation. Construction of engineered fill in accordance with this standard, and using the criteria presented in Appendix A, should result in a fill platform that will limit the settlement or deformation to acceptable levels without causing loss of amenity during construction or when in use. This standard will probably not be suitable for developments where a structure is more sensitive to differential or total settlement or deformation.

Exclusions

The following are not covered by this standard:

(a) Managing contaminated materials;

(b) Permanent cut slopes;

(c) Stability of temporary cut batters;

(d) Evaluating the suitability of existing natural ground for founding earthworks;

(e) Retaining-wall construction and retaining-wall drainage;

(f) Service construction and backfilling of service trenches;

(g) Chemically stabilised fill (for example, cement or lime);

(h) Pavement sub-base, base course, or surfacing;

(i) Contractual aspects of earthfill construction.

The processes associated with undertaking site investigations and the design of engineered fill are not covered by this standard, except to define the minimum considerations that have to be addressed in the investigation and design to achieve a stable and resilient engineered fill.