Abstract: The foundation excavations near the mountainside usually have a large excavation depth. After the foundation construction, if the gap between the foundation and the supporting system can be left open, the supporting system should be permanently stabilized. If the gap needs to be restored to its original appearance, the backfill method will usually be considered first. Excessive lateral earth pressure might adversely affect the safety of the foundation system. This paper presents a cover slab system design over gap between the excavation supporting system and the foundation. Vegetation is planted on the cover so that the site is environmentally friendly. For the backfill portion, the foundation is designed for the lateral earth pressure induced from the backfill soils; for the opening portion, the supporting system is designed for the permanent conditions; for the covered portion, the cover and supporting system have the same design requirement as the foundation system for the stability requirement such as, seismic conditions.

Key words: foundation excavation, cover slab, backfills, overlaying soils, cover slab