  The formation and evolution of the cosmic web in which galaxy superclusters
are the largest relatively isolated objects is governed by a gravitational
attraction of dark matter and antigravity of dark energy (cosmological
constant). We study the characteristic density contrasts in the spherical
collapse model for several epochs in the supercluster evolution and their
dynamical state. We analysed the density contrasts for the turnaround, future
collapse and zero gravity in different LCDM models and applied them to study
the dynamical state of the supercluster A2142 with an almost spherical main
body. The analysis of the supercluster A2142 shows that its high-density core
has already started to collapse. The zero-gravity line outlines the outer
region of the main body of the supercluster. In the course of future evolution
the supercluster may split into several collapsing systems. The various density
contrasts presented in our study and applied to the supercluster A2142 offer a
promising way to characterise the dynamical state and expected future evolution
of galaxy superclusters.
