Tunnel In Soft And Weak Surrounding Rock Strength Characteristics And Supporting Structural Stability

The presence of soft rock tunnel support, etc. to bring a series of thorny issues.Because deep rock joints, cracks existence by its mechanical behavior of rock strength,structural plane stress state,and many other conditions and the impact of the presence of hard rock joints under high stress in the course of excavation unloading still showed significant soft rock deformation and strain softening characteristics,highlighting the phenomenon of expansion of rock,rock deformation has discontinuities.For the mechanical behavior of soft rock equivalent peak after in-depth study and discussion.Papers solve the above problem,the deformation of soft rock from the tunnel failure mechanism,discusses method for determining the strength of weak rock,analyzing rock during unloading strain softening behavior and deformation damage evolution;study the role of secondary stress in rock under the stress field distribution of the displacement field,to determine structural characteristics of surrounding rock;using convergence-confinement method to determine the structure surrounding and supporting the safety factor,and the supporting structure and the tunnel excavation methods to optimize the design,through on-site monitoring and numerical calculations verify optimize the structure of security and stability. Papers draw specific conclusions are as follows:(1) Rating system based on quantitative GSI rock, soft rock tunnel to determine the peak and peak strength parameters of residual state, analyzing rock during unloading from peak to peak residual state state transformation process,combined with Hoek-Brown Standards and strain softening rock continuum theory, build soft rock peak and peak residual strength parameters of functional relationship.(2)According to the intact rock laboratory triaxial tests to determine the peak strain softening behavior of rock by determining the peak softening modulus and confining pressure relationships to build a complete model of the rock peak strain softening, combined with geological prediction methods to determine the weak rock tunnel mechanical parameters, guiding the tunnel excavation and retaining structure optimization design.(3) Convergence confinement method for large cross-sectional design of the railway tunnel supporting structure, and through software to build tunnels FLAC3D finite difference numerical model to calculate the longitudinal section of the tunnel during excavation and rock deformation curve characteristic curve, yield different the rock excavation methods-interaction between the supporting structure, made of rock excavation program safety factor, and the existing support scheme and excavation methods to optimize the design, verification through on-site monitoring tools optimized design reliability.(4)The evolutionary algorithm is applied to neurons shop Mountain Tunnel Surrounding Rock Deformation Prediction of tunnel surrounding rock deformation monitoring data for multi-step rolling forecasts show that the algorithm has high prediction accuracy, and can provide a reference for similar projects.