Abstract:  Because of the complex load distribution of surrounding rocks, giantspan flat caverns frequently face more construction challenges. The support technology of a giantspan flat underground cavern is studied to investigate the construction technology of a giantspan underground cavern (far more than 50 m-level) in China and improve cognition of supporting structure and surrounding rock stress characteristics. Through a numerical simulation analysis of anchorshotcrete support of giantspan cavern, stress characteristics of different support structures are obtained, and the supporting effect of different support structures is compared and analyzed. The results show the following: (1) The axial force of anchor cable and the internal force of shotcrete structure are relatively small during excavation process, but the tensile force of anchor cable is relatively large. (2) When removing the rock pillars on both sides, the tension of the anchor cable increases sharply. (3) The variation trend of anchor cable axial force monitoring data matches that of numerical simulation, thereby confirming the validity of the numerical simulation results. Therefore, the anchor cable can be considered to contribute to the stability of the surrounding rock throughout the construction process.

Key words: giant-span flat underground cavern, shotcrete-anchor support measures, prestressed anchor cable, stress characteristics of supporting structure