Pre-splitting method for tunneling construction

The invention discloses a presplitting method for tunneling construction. The presplitting method comprises the following steps: step 1, presplitting an upper area of a tunnel: distributing and drilling holes in the upper area of the tunnel; pre-splitting flat holes and crushing and discharging slag; 2, pre-splitting the lower area of the tunnel, wherein holes are distributed and drilled in the two sides of the lower area of the tunnel; pre-splitting the vertical hole, crushing and discharging slag; pre-splitting flat holes and crushing and discharging slag; step 3, pre-splitting an inverted arch area: pre-splitting a vertical hole; and crushing and discharging slag. According to the pre-splitting method used in the tunneling construction, a flat hole pre-splitting method and a vertical hole pre-splitting method are combined for use, the excavation contour line is accurately controlled, back break is effectively prevented, and the tunnel excavation and tunneling construction progress is remarkably improved; t