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Certification of Reinforced Fill Products
  1. Reinforced Fill Applications in Hong Kong

    In Hong Kong, the common applications of the reinforced fill technique have included the following:

    • Highway bridge abutments
    • Retaining walls for highways, railways and building platforms
    • Embankments for highways and railways
    • River training works
    • Repairs of failed slopes
    • Barriers for blast shelters and landslide/boulder fall mitigation

    Since 1981, about 100 reinforced fill structures have been, or are being constructed in Hong Kong. Many of these structures are situated in the new towns such as Tuen Mun, Yuen Long and Tsing Yi, which were developed in the 1980s to accommodate the increasing population. Extensive use of the reinforced fill technique has been made on the West Rail Project. Most of the completed reinforced fill structures range between 5 to 15 m in height, but a reinforced fill structure up to about 40 m was constructed on the mountainous coastal terrain of North West Tsing Yi to support a highway interchange that links Route 3 with the North Lantau Expressway.


    40 m high reinforced fill structure at North West Tsing Yi

    40 m high reinforced fill structure at North West Tsing Yi

     

    16m high segmental block wall at Discovery Bay

    16m high segmental block wall at Discovery Bay

  2. Common Reinforced Fill Products

    The common reinforced fill products are formed from metallic or polymeric materials. Metallic products are usually made from galvanised steel and formed as strips, grids or anchors. Polymeric products in the forms of grid or strip are commonly manufactured from polyester fibres or high density polyethylene (HDPE). Polymeric grids can be manufactured from drawn polymer sheets containing holes or formed from woven/knitted or solid structural polymeric elements (e.g. polymeric strips/bars) welded or knitted together.


    Galvanized steel strips   

    Galvanized steel strips

    Galvanized steel meshes

    Galvanized steel meshes

    Polymeric grids

    Polymeric grids

    Polymeric strips

    Polymeric grids

  3. Certification of Reinforced Fill Products

    The Civil Engineering and Development Department (CEDD) of the Hong Kong SAR Government operates a certification system to regulate reinforced fill products whose long-term tensile strength and stress-strain characteristics are temperature and/or time dependent (e.g. polymeric reinforcing products). Metallic products, the tensile strength and stress-strain characteristics of which are not dependent on temperature and time in normal application, do not require certification. According to the Environmental, Transport and Works Bureau Technical Circular (Works) No. 24/2003 "Permanent Reinforced Fill Structures and Slopes", only metallic products or certified products shall be used in permanent reinforced fill features in Government projects.


    The certification system confers a level of acceptance on reinforcing products used in permanent reinforced fill features. Permanent reinforced fill features are defined as structures or slopes constructed using the reinforced fill technique, with or without facing elements, and having an intended design life longer than two years. The certification system ensures consistent and satisfactory standards in the provision of these products, facilitates their specification, and saves time for designers, contractors, manufacturers, product distributors and the Government by eliminating repetitive checking of project proposals. Notwithstanding a certificate for the reinforced fill product, a permanent reinforced fill structure or slope incorporating a certified reinforced fill product will still need to be adequately designed, and checked by the Geotechnical Engineering Office (GEO) of CEDD.


    Application for reinforced fill product certification requires the applicant to submit sufficient information to justify the long-term tensile strength of the submitted products. The current evaluation process adopted by GEO requires the applicant to provide a submission containing physical description of the reinforced fill products, history of its use, manufacturer quality control and quality assurance programme, detailed assessment of the long-term tensile strength and the pullout and sliding resistance of the products. A detailed breakdown of the submission requirements can be viewed by clicking Download PDF (41KB). The submission shall be forwarded to the Head of GEO for assessment. The electronic copies of the current certificates including the product images can be viewed and downloaded by clicking here. Samples of the products could also be inspected in the Geotechnical Projects Division of GEO.

  4. Guide to Reinforced Fill Structure and Slope Design

    Geoguide 6 - Guide to Reinforced Fill Structure and Slope Design (2002) recommends a standard of good practice for the design and construction supervision of permanent reinforced fills structures and slopes in Hong Kong. It provides a model specification, which stipulates the general requirements on the quality of materials, standard of workmanship, testing methods and acceptance criteria for reinforced fill construction. It can be used as a reference for the preparation of particular specification.

  5. GEO Technical Guidance Note No. 40 - Guidelines on Temporary Drainage Provisions and Precautionary Measures against Severe Rainfall during Site Formation Works and Construction of Reinforced Fill Structures serves to remind practitioners of the need for adequate temporary drainage provisions and precautionary and mitigation measures against severe rainfall during site formation works and construction of reinforced fill structures. It is intended to supplement the guidance given in Sections 8 and 9 of the Geotechnical Manual for Slopes (GCO, 1984) and Sections 7, 8 and 11 of Geoguide 6 (GEO, 2002).