ADVANCED SUPPORT STRUCTURE FOR OVERSIZED VARIABLE-CROSS-SECTION TUNNEL

摘要

An advanced support structure for an oversized variable-cross-section tunnel, comprising a tunnel cross section consisting of a main hole (1) to be excavated and side holes (2) to be excavated; the side holes to be excavated are located at two sides of the main hole to be excavated; two layers of high-pressure horizontal jet grouting piles (3) are arranged outside an arch crown of the main hole to be excavated along a tunnel excavation contour line; an advanced long pipe shed (4) is embedded between the two layers of the jet grouting piles; a layer of high-pressure horizontal jet grouting piles (3) is arranged outside the arch crowns of the side holes to be excavated along a tunnel excavation contour line; a plurality of high-pressure horizontal jet grouting piles (3) are arranged outside an arch foot between the side holes to be excavated and the main hole to be excavated along the tunnel excavation contour line; a plurality of high-pressure horizontal jet grouting piles is arranged at a tunnel face arch portion (5) of the main hole to be excavated in a tunnel excavation direction; and a plurality of advanced glass fiber anchor pipes (7) is arranged on tunnel face core soil (6) of the main hole to be excavated in the tunnel excavation direction. The advanced support structure ensures the excavation safety of an oversized variable-cross-section tunnel in particularly weak surrounding rock, reduces the use of temporary supports, increases the degree of freedom in operation, and accelerates a construction process.