Setting three-dimensional drainage system which is composed drainage culvert and horizontal

vertical and acclivitous drainage bore in loess landsliding body

is an effectual method for dropping the underground water level and improving the stability of slope

but its effection estimation is a problem. The 3D seepage numerical analyze is an effectual method to solve the difficulty. The three-dimensional drainage system in a typical loess landsliding body at Guanzhong section of Weihe River is simulated with 3D seepage numerical analyze method. The results show that because of complexity of stratum in landsliding body

the infiltrative coefficients obtained with indoor testing do not accord with naturalness

the anti-analyze is needed according to the determined underground water level on the spot; the space and position between drainage bore hugely influence the effect of dropping the underground water level.