The disc-binary interaction leads to the evolution of the binary’s orbit. The binary could lose
its orbital angular momentum which can be transported to the circumbinary disc through
orbital resonances. At the same time, the binary can acquire specific angular momentum from
the disc through viscous torques that cause the formation of spiral arms and the accretion of
material onto the binary through these arms. Previous simulations using the SPH code have
shown that the evolution of the binary’s orbit may be influenced by various parameters of
the system. In this study, we improve our setup by considering the the steady state thick disc
and varying parameters such as the mass ratio of the binary, the alpha viscosity, the size of
the disc, the mass of the disc and the resolution. Most importantly, we only allow the binary
to feel the disc after the disc reaches the quasi-steady state, which was not considered in
previous studies. Hence, the binary prevents from additional effects of the initial setup of the
simulation. Because the thick disc tends to form strong spiral arms, these spiral arms promote
the mass accretion onto the binary. As a result, the binary is expected to expand along with
the thick disc, and this is indeed observed in most of our simulations, except for those with
high viscosity and binary mass ratios of ? 1/3. We conclude that a thick disc may still shrink
due to the effect of the mass ratio. Our results have implications in a variety of astrophysical
objects including the orbital evolution of stellar binaries and the evolution of both stellar and
supermassive black hole binaries.