GEOGRID-REINFORCED WALL WITHSTANDS EARTHQUAKE

The design and construction are described of a geogrid reinforced wall system on a dramatic hillside in San Bruno, California to create stable panoramic building sites within 300 feet of the San Andreas fault. The hill consists of a 50 foot high natural 1H:1V slope at its base, surmounted by an 18 foot high reinforced soil wall with attractive masonry facing units. The hill is topped by a 3 foot high 2H:1V engineered fill slope leading to a roadway above. The geogrid system used had the advantage of developing much of its strength and stability from the reinforced soil mass instead of relying entirely upon the integrity of the outboard weathered bedrock to support the wall foundation. This it could withstand a large surcharge load and would be a low height. The reinforced soil system also is compliant under conditions of differential movement. This geogrid reinforced wall system has proved to be a cost effectivce and aesthetically pleasing design alternative for a site with significant slope, geologic and soil constraints.