Problems with rock deformation due to simulated infiltration

Hi all. i have recently been simulating a process in the Richards Mechanics module and have run into some problems.
The process I am trying to simulate is a deformation of a rock mass due to water infiltration in the upper part of the rock mass. The boundary conditions I have set up are that there is no displacement on the sides or bottom, the water is flowing from top to bottom, the water flows in from the top and out from the bottom, and there is no inflow or outflow of water from the sides. The result “pressure” has some problems. Maybe there is something wrong with my boundary conditions, but I don’t know how to change them, so I hope you can help me.

Here is my documentation on this. (55.9 KB)

In addition, I would like to know how to set my boundary conditions if I want to change the infiltration of water to the change of hydraulic head.

Thank you all!