The project is located in the ancient city district of Kunming. It is consisted of the ground 10 to 22-story residential buildings, three layers podiums and underground garages and other buildings. The total area is about 110m × 82m, which are configured two basements. The foundation depth is -10.4m, which is a large deep pit.
Apply reinforced soil nailing support system in the height between 0~-4m and extended soil nailing system between -4.0~-10.4m).
According to geological survey data, take C averagely 20.0 kPa, γ is 21.0 kN / m, φ is 20o; according to the calculated erect excavation,β is taken as 90 °, and the calculated result is 3.6 meters. Soil Nailing row spacing distance is 1.5 m.
Positioning
According to the design of rod spacing, position each bolt on the slope and make marks, and holes error should be less than 100mm.
Drilling and Installing
(1) The hole diameter is not less than the designed diameter (100-130mm);
(2) The angle should be controlled between 50-100;
(3) Drilling should make a record, and after passing the examination it can be carried out in the next process.
Grouting
Grouting cement ratio is 0.5 to 0.55, but it can be properly adjusted in the special formation. The pressure can not be less than 0.3MPa. Cement injected should be full enough.
Netting
Netting and banding according to the designed spacing and protective layer. The lap length should meet the regulatory requirements, and hooks mesh reinforcement and soil outside the top of the rod should be welded into a whole.
Finally, spray concrete.