Gully landform tunnel portal structure and construction method thereof

The invention relates to a gully landform tunnel portal structure and a construction method thereof. The related structure comprises an upward slope and a side slope which are arranged on a gully landform mountain body; a tunnel portal is formed in the slope bottom of the upward slope of the gully landform; the top of the gully landform mountain body is provided with an intercepting ditch; a side ditch is arranged at the foot of the slope of the gully landform. The related construction method comprises the steps of firstly clearing surface layer weathered rock bodies in a gully, and constructing the tunnel intercepting ditch at the mountain top of the gully; excavating the side slope and the upward slope of a tunnel from top to bottom, and constructing a platform as an intercepting ditch at a platform of the upward slope and the slope of the gully; then constructing a sleeve arch and a pipe shed and performing tunnel primary support bracing under protection of the pipe shed; finally constructing the side ditch outside the tunnel portal. According to the method, an open cut tunnel does not need to be lengthened, the whole length of the tunnel is shortened, the engineering construction cost is reduced, and the economic benefits are improved.