simulation of wet powder

Hello,

I am trying to simulate a wet powder and calculate the friction between the substrate and the powder.

I'm trying to calculate the friction force from the spring force.
This is a simple model.
Spring the substrate and the block together and move the block. This creates friction between the block and the powder. This is calculated as the spring force equals the friction.

Now the "fix insert/pack" command doesn't work for creating particles.

I've posted the file and would like your advice.