Large-section chamber layered tunneling construction method

The invention discloses a layered tunneling construction method for a large-section chamber, and belongs to the field of chamber construction methods, a slope ramp with a proper gradient is arranged as a measure lane, a construction surface is lifted to an upper layer of the large section of the chamber, the upper layer is firstly tunneled during construction, and middle and lower layers are sequentially constructed after the upper layer is completely constructed, so that the large-section chamber is constructed. The construction safety problem that the exposed area of a top plate is too large and the exposed time is too long during middle and lower layered construction is avoided, the construction mode of the top layer of the chamber is set to be the mode of small pilot tunnel tunneling and temporary supporting-expanding brushing and temporary supporting-smooth blasting and anchor net spraying supporting, and after small pilot tunnel expanding brushing is completed, a compensation space is formed in the midd