how can i increase the load gradually

Hi my friends,

i am using Abaqus 6.6, i want to apply a load on rock sample, this load increases with increasing time, for example, the first minute the magnitude of load is 100 Psi, and the second minute 200 psi, and the third minute 300 psi, and so on.

how can i do this?

thanks alot

Gamal