Space effect of soil-nailing excavation protection

A three-dimension elastoplastic model had been developed to study the space effect of the soil-nailing excavation protection.The positive corner effect,negative corner effect and layered excavation were emphatically analyzed.The researches showed that: the negative corner of excavation could reduce the displacement of excavation and the force of soil-nail;and its influence was once more than the depth of the excavation;meanwhile,the displacement of the excavation and the force of soil-nailing were much larger in the positive corner;and its influence is near to 3 times of the depth of the excavation;the space effect of soil-nailing pit could be used plenarily by layered excavation;its influence was near to the depth of the excavation.It was proved that three-dimension numeric analysis of the soil-nail structure was very useable.