ON DESIGN OF CAVE ENTRANCE SECTION OF A HIGHWAY TUNNEL
QIAN Wang-ping;School of Architectural Engineering, Nantong University;
Cave entrance section of a highway tunnel has complex geological and hydrological conditions, with cave being shallow in pre-burial depth and wall rock poor in self bearing capacity, so landslide, cave-in and great deformation often occur in construction. Based on actual engineering design and construction practices, this paper put forward factors and technical measures that need to be considered in design of cave entrance section, including determination of cave entrance place, function and method of surface reinforcement, excavation and strengthening of side and face-upward slope of entrance, advance support, etc under different geological and landform conditions. Integrated consideration of natural conditions of cave entrance section and reasonable application of corresponding technical measures can ensure construction safety and engineering quality, and save engineering cost.