Excavating construction method for special stratum cave

The invention relates to the field of cave excavation, and particularly relates to an excavating construction method for a special stratum cave. The method comprises the steps that one, construction instruments preparation and personnel configuration are conducted, and measuring sample releasing is conducted on a construction region; two, excavating and supporting are conducted on a small cave, excavating is conducted by adopting blasting or a tunnel boring machine, slags are timely discharged, the excavating length of each circulation is 0.5 m-0.7 m, and a steel arch frame and an anchoring net are timely adopted to perform supporting after the slags are completely discharged; three, the excavating and supporting of the upper portion of a middle pilot tunnel are conducted; four, the reverse expanding excavating of upper steps of a large cave is conducted; five, the excavating and supporting of a middle step of a large cave are conducted; six, the excavating and supporting a lower step(inverted arch) of the la