  We suggest to use "minimal" choice of quantum gravity theory, that is the
quantum field theory, in which space-time is seen as Riemannian space and
metric (or vierbein field) is the dynamical variable. We then suggest to use
the simplest acceptable action, that is the squared curvature action. The
correspondent model is renormalizable, has the correct classical limit without
matter and can be explored using Euclidian path integral formalism. In order to
get nonperturbative results one has to put this model on the lattice. While
doing so serious problems with measure over dynamical variables are
encountered, which were not solved until present. We suggest to solve them
using the representation of Riemannian space as a limiting case of Riemann -
Cartan space, where the Poincare group connection plays the role of dynamical
variable. We construct manifestly gauge invariant discretization of Riemann -
Cartan space. Lattice realization of Poincare gauge transformation naturally
acts on the dynamical variables of the constructed discretization. There exists
local measure invariant under this gauge transformation, which could be used as
a basic element of lattice path integral methods. The correspondent lattice
model appears to be useful for numerical simulations.
