Impact Force plotting using Abaqus/Explicit

Hello Everyone

I am trying to simulate material dumping process from shovel onto mining dump truck. And for that i am using Abaqus/Explicit.  When i plot the contact force of material falling onto truck body under gravity, it gives me the maximum value of 0.12e+11, where as a simple theoretical analysis shows that the resulting impact force for 100 tons of material falling under gravity should be 9e5 N. I am not been able to understand the reason that why Abaqus /Explicit is exaggerating the impact/contact force so much. And i dont know how to correct this thing.

Units are as follows:

Mass= kg

Distance/Displacement = mm

Kindly help me out in this situation.

Thanks,

Danish