\documentclass{article} % say
\usepackage{tikz}
\begin{document}
%We are working on
\usetikzlibrary{patterns}

% traits horizontaux

\begin{tikzpicture}%[scale=1.5]

\node (A) at (-8,8) [coordinate] {} ;
\node [above left] at (A) {$A$} ;
\node (B) at (-8,3) [coordinate] {} ;
\node [below left] at (B) {$B$} ;
\node (C) at (0,0.5) [coordinate] {C} ;
\node [below right] at (C) {$C$} ;
\node (D) at (4,5) [coordinate] {} ;
\node [above right] at (D) {$D$} ;

\draw (A) -- (B) -- (C) -- (D) -- (A) -- (C);
\draw [dashed] (B) --  (D) ;

\node (a) at (2,3) [coordinate] {} ;
\node [below right] at (a) {$a$} ;
\node (b) at (-8,5.5) [coordinate] {} ;
\node [above left] at (b) {$b$} ;

\draw [line width=2pt, dashed] (B) --  (a) -- (b);
  
  
  \draw (-8,-1.5) -- (2,-1.5);
  
  
\draw[line width=0cm, color=white](0,3) coordinate (j_1) -- (-2,0.5) coordinate (j_2);
\coordinate (j) at (intersection of B--C and j_1--j_2);
 \draw (j_1) -- (j);
 \draw[line width=0cm, color=white](0,3) coordinate (j_1) -- (0,6) coordinate (j_3);
 \coordinate (j_4) at (intersection of b--a and j_1--j_3);
  \draw (j_1) -- (j_4);
    \draw (j) -- (j_4);
    
    \draw[line width=0cm, color=white](-1.5,3) coordinate (k_1) -- (-3.5,0.5) coordinate (k_2);
\coordinate (k) at (intersection of B--C and k_1--k_2);
 \draw (k_1) -- (k);
 \draw[line width=0cm, color=white](-1.5,3) coordinate (k_1) -- (-1.5,6) coordinate (k_3);
 \coordinate (k_4) at (intersection of b--a and k_1--k_3);
  \draw (k_1) -- (k_4);
    \draw (k) -- (k_4);

  \draw[line width=0cm, color=white](-3,3) coordinate (m_1) -- (-5,0.5) coordinate (m_2);
\coordinate (m) at (intersection of B--C and m_1--m_2);
 \draw (m_1) -- (m);
 \draw[line width=0cm, color=white](-3,3) coordinate (m_1) -- (-3,6) coordinate (m_3);
 \coordinate (m_4) at (intersection of b--a and m_1--m_3);
  \draw (m_1) -- (m_4);
    \draw (m) -- (m_4);

  \draw[line width=0cm, color=white](-4.5,3) coordinate (p_1) -- (-6.5,0.5) coordinate (p_2);
\coordinate (p) at (intersection of B--C and p_1--p_2);
 \draw (p_1) -- (p);
 \draw[line width=0cm, color=white](-4.5,3) coordinate (p_1) -- (-4.5,6) coordinate (p_3);
 \coordinate (p_4) at (intersection of b--a and p_1--p_3);
  \draw (p_1) -- (p_4);
    \draw (p) -- (p_4);

  \draw[line width=0cm, color=white](-6,3) coordinate (q_1) -- (-7.5,0.5) coordinate (q_2);
\coordinate (q) at (intersection of B--C and q_1--q_2);
 \draw (q_1) -- (q);
 \draw[line width=0cm, color=white](-6,3) coordinate (q_1) -- (-6,6) coordinate (q_3);
 \coordinate (q_4) at (intersection of b--a and q_1--q_3);
  \draw (q_1) -- (q_4);
    \draw (q) -- (q_4);

\draw (-3.5,5.5) node{$\pi_2$};
\draw (1.5,4) node{$\pi_1$};
\draw (-4.2,1.5) node{$\pi_0$};
\draw (-4,-1.8) node{$\tau$};

\draw[->] (-3,0.2) -- (-3,-1);
\draw (-3.3,-0.4) node{e};
  
        \end{tikzpicture}
\end{document}

