Development and application of composite soil nailing walls in Shenzhen

The history of development and application of composite soil nailing walls in Shenzhen area were introduced.Four types of new composite soil nailing walls usually used in Shenzhen area were summarized.These composite walls included combination of soil nailing with cut-off wall(deep mixing piles or jet grouting piles) and prestressed anchors,combination of soil nailing with prestressed anchors,combination of soil nailing with micropiles and prestressed anchors,and combination of soil nailing with prestressed anchors,cut-off wall and micropiles.Design and calculation methods using a circular sliding method for checking the overall stability and the calculation method of pullout resistance of soil nailing were presented.The structural characteristics of soil nail,cut-off wall,prestressed anchor and micropile were also introduced.Finally,a successful application example using composite soil nailing wall was described.In the example,the composite soil nailing was used as a supporting system for deep foundation pit excavation at a site where difficultly geological conditions exist.