  We study the orbital evolution of a three planet system with masses in the
super-Earth regime resulting from the action of tides on the planets induced by
the central star which cause orbital circularization. We consider systems
either in or near to a three body commensurability for which adjacent pairs of
planets are in a first order commensurability. We develop a simple analytic
solution, derived from a time averaged set of equations, that describes the
expansion of the system away from strict commensurability as a function of
time, once a state where relevant resonant angles undergo small amplitude
librations has been attained. We perform numerical simulations that show the
attainment of such resonant states focusing on the Kepler 60 system. The
results of the simulations confirm many of the scalings predicted by the
appropriate analytic solution. We go on to indicate how the results can be
applied to put constraints on the amount of tidal dissipation that has occurred
in the system. For example, if the system has been in a librating state since
its formation, we find that its present period ratios imply an upper limit on
the time average of 1/Q', with Q' being the tidal dissipation parameter. On the
other hand if a librating state has not been attained, a lower upper bound
applies.
