Study On Construction Mechanical Behavior Of Highway Tunnel Traversing Single Coal Seam Mined-Out Area Stratum

With the rapid development of transportation roadways construction in China in recent years, the available land resources gradually decrease, the demand of road line selection is more strict, and highway tunnels inevitably traverse mined-out area stratum. Construction of highway tunnel in the existing mined-out area will be to change the stress field distribution of stratum, will seriously impact on the surrounding rock stability of mined-out area, especially in the intersection area of mined-out and tunnel, ground stress field distribution is extremely complex, and harm on highway tunnel cannot be ignored and potential. So how to ensure tunnel construction safety in mined-out area stratum is a urgent problem to be solved. Studying on construction mechanical behavior of tunnel traversing mined-out area stratum is very necessary and has important engineering significance. Based on the Guan Dou Mountain Tunnel, Yi (Bin)-Lu (Zhou) Expressway Project, such two research means as laboratory similar model test, numerical simulation analysis are applied to systematically study construction mechanical behaviors of bi directional four-lane and about12.5m width highway tunnel traversing goaf stratum. Main Research Findings are as follows:1. Putting forward the cross-sectional and longitudinal critical spacing of tunnel excavation for overlying-goaf tunnel and underlying-goaf tunnel.2. Based on plane strain assumption,2D numerically analyzing cross-sectional influence rules of mine goaf on convergence of tunnel inner perimeter, surrounding rock stress, axial force of anchor bolt and the internal force of primary support (including moment and axial force), which are caused by tunnel construction, and influence rules of construction disturbance on the goaf ground movement, While tunnel overlying goaf (or underlying goaf).3. laboratory similar simulation analysis is carried out on the influence of tunnel construction on the goaf ground movement and the influence of mine goaf on mechanical characteristics of primary support with different excavation supporting conditions.4.3D numerically analyzing the tunnel traversing mine goaf stratum, studying on longitudinal influence rules of mine goaf on convergence of tunnel inner perimeter, surrounding rock stress, axial force of anchor bolt and the internal force of primary support, and influence rules of construction disturbance on the goaf ground movement.