Spatial Effect Research For Soil-nail Supported Stucture

In this paper three-dimension elasto-plastic model had been builded by software FLAC3D to take into accout the function between soil and the soil_nail supported structure .used Cable Element to simulate the function between soil and soil_nail;also three-dimension elasto-plastic model had been developed to study the space effect of the soil-nailing pit protection. The positive corner effect, negative corner effect and layered excavation were emphatically analyzed. Anaylsis showed that, the positive corner of pit can reduce the displacement of pit and the force of soil-nail, and its incidence was larger than the depth of the excavation pit; otherwise, the displacement of the pit and the force of soil-nail were much larger in the negative corner, and its incidence was near to 2 times of the depth of the pit;layered excavation can plenty use the space effect of soil-nailing pit, reduce the development of the deform of the soil and the force of the soil-nail, this is good for the stabiliy of the pit, and its incidence was near to the depth of the pit In the end , it introduced the Strength Reduction Fern , and used it to analyse the stablility of slopes, the result agreed with the result of 《Technical specification for retaining and Protection of Building Foundation Excavation》 .