  Observations indicate that most massive stars in the Galaxy appear in groups,
called OB associations, where their strong wind activity generates large
structures known as superbubbles, inside which the subsequent supernovae (SNe)
explode, in tight space and time correlation. Acknowledging this fact, we
investigate four main questions: 1) does the clustering of massive stars and SN
explosions influence the particle acceleration process usually associated with
SNe, and induce collective effects which would not manifest around isolated
supernova remnants?; 2) does it make a difference for the general phenomenology
of Galactic Cosmic Rays (GCRs), notably for their energy spectrum and
composition?; 3) can this help alleviate some of the problems encountered
within the standard GCR source model?; and 4) Is the link between superbubbles
and energetic particles supported by observational data, and can it be further
tested and constrained? We argue for a positive answer to all these questions.
Theoretical, phenomenological and observational aspects are treated in separate
papers. Here, we discuss the interaction of massive stellar winds and SN shocks
inside superbubbles and indicate how this leads to specific acceleration
effects. We also show that due to the high SN explosion rate and low diffusion
coefficient, low-energy particles experience repeated shock acceleration inside
superbubbles.
