  The problem of the description of the orbit space $X_{n} = G_{n,2}/T^n$ for
the standard action of the torus $T^n$ on a complex Grassmann manifold
$G_{n,2}$ is widely known and it appears in diversity of mathematical
questions. A point $x\in X_{n}$ is said to be a critical point if the
stabilizer of its corresponding orbit is nontrivial. In this paper, the notion
of singular points of $X_n$ is introduced which opened the new approach to this
problem. It is showed that for $n>4$ the set of critical points
$\text{Crit}X_n$ belongs to our set of singular points $\text{Sing}X_{n}$,
while the case $n=4$ is somewhat special for which $\text{Sing}X_4\subset
\text{Crit}X_4$, but there are critical points which are not singular.
  The central result of this paper is the construction of the smooth manifold
$U_n$ with corners, $\dim U_n = \dim X_n$ and an explicit description of the
projection $p_{n} : U_{n}\to X_{n}$ which in the defined sense resolve all
singular points of the space $X_n$. Thus, we obtain the description of the
orbit space $G_{n,2}/T^n$ combinatorial structure. Moreover, the $T^n$-action
on $G_{n,2}$ is a seminal example of complexity $(n-3)$ - action. Our results
demonstrate the method for general description of orbit spaces for torus
actions of positive complexity.
