  Based on the realistic nuclear force of the high-precision CD-Bonn potential,
we have performed comprehensive calculations for neutron-rich calcium isotopes
using the Gamow shell model (GSM) which includes resonance and continuum. The
realistic GSM calculations produce well binding energies, one- and two-neutron
separation energies, predicting that $^{57}$Ca is the heaviest bound odd
isotope and $^{70}$Ca is the dripline nucleus. Resonant states are predicted,
which provides useful information for future experiments on particle emissions
in neutron-rich calcium isotopes. Shell evolutions in the calcium chain around
neutron numbers \textit{N} = 32, 34 and 40 are understood by calculating
effective single-particle energies, the excitation energies of the first $2^+$
states and two-neutron separation energies. The calculations support shell
closures at $^{52}$Ca (\textit{N} = 32) and $^{54}$Ca (\textit{N} = 34) but
show a weakening of shell closure at $^{60}$Ca (\textit{N} = 40). The possible
shell closure at $^{70}$Ca (\textit{N} = 50) is predicted.
