Civil Engineering Association

This Geoguide recommends a standard of good practice for the design and construction supervision of permanent reinforced fill structures and slopes in Hong Kong. It is a companion to Geoguide 1 − Guide to Retaining Wall Design (GEO, 1993) and is aimed at qualified engineers who are conversant with the relevant engineering principles and procedures. Reinforced fill is a compacted mass of fill with predominantly horizontal layered reinforcing elements to improve its tensile and shear capacities. Permanent reinforced fill features are made of reinforced fill, which may also comprise facing elements to form slopes or structures with an intended design life longer than two years. A reinforced fill feature with a face inclination of more than 20º from the vertical shall be considered as a reinforced fill slope. A reinforced fill feature otherwise shall be considered as a reinforced fill structure. The geotechnical standards set out in this Geoguide is for new permanent reinforced fill features, including retaining walls, bridge abutments, segmental block retaining walls and reinforced fill slopes. Temporary reinforced fill structures and slopes can also be designed using the document. The Geoguide does not cover soil nailing, reinforced fill dams, maritime structures, structures which are in an estuarine or marine environment, reinforced fill foundations for embankments on soft ground and the stability assessment of existing reinforced fill structures and slopes. General considerations relating to potential applications, advantages and limitations of different reinforced fill systems are provided in Chapter 2. The concept and principles of reinforced fill, together with the factors that affect the behaviour of reinforced fill are explained in Chapter 3. In addition, general design formulae for assessing interaction between fill and reinforcement (i.e. pullout and direct sliding resistance) are provided for various forms of reinforcement (i.e. strips, grids sheets, anchors) in Chapter 3. Details of the construction materials commonly used to form reinforced fill structures and slopes are given in Chapter 4. Chapter 5 covers the specific ground investigation and testing associated with the design and construction of reinforced fill features. In line with Geoguide 1, the limit state approach has been adopted in this Geoguide. The appropriate partial safety factors on loading, materials and fill-reinforcement interaction, together with the factors which need to be considered in design are given in Chapter 6. Guidance on the design of reinforced fill structures including segmental block retaining walls is given in Chapter 7. Chapter 8 covers the design of reinforced fill slopes. Guidance on aesthetics and landscape treatment of reinforced fill structures and slopes is covered in Chapter 9. The procurement of and specification for reinforced fill construction relating to common construction practices are addressed in Chapter 10. Guidance on construction control is given in Chapter 11. There are a few terms used with specific meanings in this Guide. These meanings are given in the Glossary of Terms at the end of the document.