Method for constructing underground large building by combining top-down construction method technology with sequence construction method technology

The invention discloses a method for constructing an underground large building by combining the top-down construction method technology with the sequence construction method technology. The method comprises the following steps of: firstly, closing and dividing one half road surfaces into at least three segments through intervals ranging from 30 to 40 meters, and digging pile holes until reaching a supporting layer; secondly, carrying out reinforced concrete construction on the pile holes until reaching the height marks of installation of a base plate, embedding a steel column positioning member at the top of the base plate, fixing a steel column on the positioning member, regarding the top of the steel column as the height mark of installation of a top plate, and excavating the road surface until reaching the height mark of installation of the top plate; thirdly, obtaining the top plate through sequence construction; fourthly, refilling the earth to restore the road surface; fifthly, carrying out the steps (