Research on mechanical properties and reasonable parameter values of soft rock in deep buried tunnel
In order to explore the mechanical properties and reasonable parameter values of deep buried soft rock,the triaxial tests were conducted under high confining pressure conditions to study the mechanical properties of Silurian shale in the water diversion project from Three Gorges reservoir to Hanjiang river.Based on the experimental results,the influence of different dip angles on the mechanical properties and failure modes of shale was analyzed.Based on various methods such as experimental research,theoretical analysis,engineering analogy and inversion,and normative verification,a reasonable mechanical parameter values for deep buried soft rock is proposed.At the same time,the outer envelope of the inversion value of crustal stress was used to determine the crustal stress values for different burial depths in the soft rock cave section.Through research,it has been found that as the confining pressure increases from low to high,the cohesive force of rock samples continuously increases,and the internal friction angle continuously decreases.When the dip angle of the bedding plane is 0°,the strength of the shale sample is the highest.When the dip angle of the bedding plane is 55°,the strength is the lowest,and the rock failure surface at this angle is consistent with the bedding plane.Based on the results of triaxial compression tests,H-B strength criterion,analogy of tunnel engineering in the same stratum,and theoretical inversion using convergence constraint method,a reasonable mechanical parameter value method for deep buried soft rock is summarized,which can reflect the influence of confining pressure on the equivalent mechanical parameters of rock mass.Finally,the strength-to-stress ratio and excavation deformation were used to predict and evaluate the deformation level of deep buried soft rock in the water diversion project from Three Gorges reservoir to Hanjiang river.
rock mechanicsdeep-buried tunnelsoft rockmechanical propertiesmechanical parametersdeformation mechanism
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