1 results about "Step method" patented technology

A bilateral expanding excavation construction method for a middle pilot tunnel of a tunnel is provided. Section or excavation width of the middle pilot tunnel is generally not larger than that of a common double-line or double-lane tunnel; a step construction method is adopted, and the construction method is the same as that of a common double-line or double-lane tunnel; and the construction method is familiar to constructors, and the construction difficulty is avoided. A primary support section of the middle pilot tunnel can be expanded and excavated after being closed by at least 3 meters; if a side tunnel face is stable, and the problem of the operation height of manual installation of a steel frame and an anchor rod is solved, one-time excavation and support can be achieved, and the construction is more convenient; or otherwise, a side tunnel is excavated according to a two-step or three-step method. The primary support of the middle pilot tunnel can be timely closed; the primary support of the side tunnel and the primary support of the middle pilot tunnel can be completely connected in sequence, and various errors and deformation influences of surrounding rocks and the supportare left at an inverted arch part for treatment; and the construction progress is basically the same as that of the common double-line or double-lane tunnel.