富水弱胶结砂岩地层围岩破坏机理与控制技术研究

With the in-depth implementation of the"Western development"strategy and the"Belt and Road"initiative,China's energy development and infrastructure construction are gradually transferred to the western region,and more and more projects will encounter weakly consolidated sandstone formation in the future underground engineering construction process.In this paper,the correlation between water content and mechanical parameters of weakly cemented sandstone is quantitatively analyzed through triaxial tests of different confining pressures and different water content,and the relationship between elastic modulus,peak internal friction Angle,peak cohesive force,residual internal friction Angle,residual cohesive force and expansion Angle and water content is given.In order to study the influence mechanism of water on the overall stability of surrounding rock of weakly consolidated sandstone formation,based on the given equation and combined with the finite difference principle,a semi-analytical solution of the phased failure of surrounding rock of weakly consolidated sandstone formation tunnel excavation considering water weakening effect was derived.The results show that surrounding rock parameters gradually deteriorated from natural state to water-saturated state.The peak value of tangential stress decreases from 12.32MPa to 11.51MPa,and the displacement of surrounding rock increases from 0.14m to 0.57m,which reveals the hierarchical failure phenomenon of surrounding rock in two stages.