How to set boundary conditions

[PEI0214]

Hi，
I am simulating the shear process of the soil, but when there is a deviating stress, it creates a very large horizontal displacement, which is not normal. What is the reason for this? I set the boundary conditions as follows:

[Functions]
  [zhouya]
    type = PiecewiseLinear
    x = '0 3600 10800 21600'
    y = '0 5e5  5e5   1e6'
  []
  [weiya]
    type = PiecewiseLinear
    x = '0 3600 10800 21600'
    y = '0 5e5  5e5  5e5'
  []
[]

[BCs]
  [Pressure]
    [load1]
      boundary = 'upface'
      function = zhouya
    []
    [load2]
      boundary = 'boundface'
      function = weiya
    []
  []

  [no_z_disp_at_bottom]
    type = DirichletBC
    variable = disp_z
    value = 0
    boundary = 'downface'
  []

  [topdrained]
    type = DirichletBC
    variable = porepressure
    value = 0
    boundary = 'upface'
  []
[]

Thanks for your help.

[GiudGiud]

hello

@PEI0214 what units are the pressures in zhouya and weiya?

Guillaume

[lynnmunday]

How many dimensions is your problem? I only see a bc set on disp_z.