Optimization Of The Forms And Supporting Parameters Of Large Cross Section Tunnel

The large cross section tunnel had been constructed more and more for its beautiful line type and high utilization ratio. Along with the construction of large cross section tunnels, the research of the tunnel's characteristics, mechanics and stabilities had also been rapidly developed, this dissertation is produced under in environment.First, special characteristics of the large cross section tunnel has been summarized based on the monitoring data; study has been developed focused on the mechanics of wall rock and supporting structures of tunnel; the mechanical behavior of arch, side wall and invert had been studied; the behavior of the core rock pillar of large cross section tunnel and the rock pillar of small clear-span tunnel has been compared; the MSC.MARC had been adopted in this paper to establish 3-D numerical analysis model to validate the deformation law of the wall rock and supporting structures.The necessity of increasing the thickness of shot concrete with the raise of the cross section of tunnel has been studied and it is feasible to change the thickness of shot concrete with the construction procedure. The influence of the caking property effects on the stability of the first lining had been discussed. The deformation magnitude of the lining caused by removing the temporary support on different time had been compared and the conclusion can be used into practice. The failure type ofthe shot concrete has been generalized; the formula of the excavation length of thelow bench has been founded. Based on the software platform of GeoFBA(?) , objectfunction and boundary condition had been established, the forms of the large cross section tunnel under the V grade rock condition had been optimized.There are core rock pillar in the section when the twin sidewall drift construction method had been adopted in the large cross section tunnel, since the geological condition of the rock is bad. The mechanical and engineering behavior of the core rock pillar had been researched in detail; the key elements which effects the...