Authors present a composite support style consisting of composite soil nail and row of piles uniting ring inner support.

In this article, basing on successful instances of design of foundation pits with arch brace, the superiority of arch brace to normal brace concerning structural and construction characteristic is analyzed.

Based on the analysis of a deep excavation case in soft soil of Wuhan,one kind of new stage composite retaining and protecting structure is presented,including the combined bolting and shotcrete for upper slope cutting and unloading supporting,the hole drilling grout pile and the single-layer double-circular beam bracing system for the lower part supporting.

Then,emphases are put on some of the key techniques,including treatment of micro confined groundwater,design of the north side which is close to the Huangpu River,design of super large circular structs,and design of the peripheral part of the bottom slab which is used as struct.

Based on a practical project in downtown,discuss retaining structure for deep designand construction,adoption retaining structure for deep of two roundness bracing system underground wall,solved the problem of waterstop,displacement,excavated earthwork.