Underground cavern construction method and supporting structure

The invention provides an underground cavern construction method and a supporting structure, and relates to the technical field of underground cavern construction.The underground cavern construction method comprises the following steps that an upper cavern is excavated along a preset route, a top arch layer is permanently supported, and tie anchor rods are installed; a lower cavern is excavated downwards, two-time deep presplitting blasting is adopted, the depth of each time is half of the total blasting depth, rock ballast is removed, and temporary supporting is carried out; reinforced concrete is poured on the top arch layer to form a lining, inclined rafts are reserved, and anchor cables are symmetrically arranged on the side edge of the concrete lining of the top arch layer; performing deep pre-splitting blasting and anchor-shotcrete support on the lower cavern in sequence until the lower cavern is formed; and finally, bottom plate and side wall concrete of the lower cavern is poured and is connected with