A series of numerical tests for soil-nailing structure in the sandy

silty and soft soil media are performed. Test results show that

in soft soil medium

the pit displacement is much larger than sandy medium

and the failure mode will change from overturning mode of sandy soil to flowing mode of soft clay; and the structure can not meet the demand of bearing capacity. Among soil parameters

c & ? values are the main factors causing above-mentioned change of failure mode; otherwise K0 value mainly change the magnitude of displacement. Among supporting parameters

nail-density evidently controls the displacement of soil between two rows nails. Nail-length remarkably controls the displacement of upside soil in sandy medium and of underside soil in soft soil medium respectively. The influence of nail-rigidity is embodied as that of rigidity ratio of nail to soil

which is not basically controlled by soil type

but reinforcing bars. Also

the critical supporting parameters are achieved.