Parameters confusion

I have some problems with the parameters section of the code file.
First,there are four spring stiffness, km , kg, kt and ktm. My understanding is that km represents side wall normal stiffness and kg is grain’s narmal stiffness, kt is grain grain tangential stiffness , ktm is bottom and top wall’s tangential stiffness, but why the right wall and left wall’s tangential stiffness is not involved .I don’t know if my understanding is correct.
Second, I have questions about nuf , nugt and mug. I 'm confused about these parameters.
Third, there’s a code line like that: real r=1e-3;
I want to make sure that the parameter, ‘r’, is the conversion factor from millimeter to meter.
The last question is about the model. If I want to build a container, 5 meters long and 0.6 meters high, how should I do? If spacing of each grids is 0.1 millimeter , I shoud modify the code as follows:
#ifndef lx
#define lx 50001
#endif
#ifndef ly
#define ly 6001
#endif
This operation will result in a huge memory occupied that cannot be calculated, prompt error:core has been dumped.
I noticed that there’s a parameter named scale. What do I need to do to use the parameter, scale, to model without using equal proportion?
Could you please give me some help?