### STRESS STATE OF TRANSVERSELY ISOTROPIC ROCKS NEAR PRESSURIZED HYDRAULIC TUNNEL OF HORSESHOE CROSS-SECTION

Pages 1172-1179

The parametric analysis of the stress state of a transversally isotropic rock mass near a pressurized hydraulic tunnel of a box-shaped form is carried out. Pressurized hydro-technical tunnels of box-shaped cross-section are widely used in the field of hydraulic engineering construction and are one of the complex, labor-intensive and expensive types of structures that make up the main structures of waterworks, melioration systems and water supply systems. As a culvert and water supply facilities they are built underground if the open excavation is impossible or not economical, or when the tunnel runs through a densely populated or densely built-up area, or when landslides, screes, rockfalls are possible. Violation of integrity of the rock mass, in particular, caused by tunneling, modifies the stress-strain state (SSS) of the rock mass, which leads to appearance of tensile stresses in some places, and in some cases, to significant compressive stresses. If these stresses exceed the design strengths of rock to tension and compression, respectively, then the collapse of the working roof and buckling of the side walls and the bottom of the tunnel may occur. Subject: analysis of the stress state of transversally isotropic rocks near the pressurized hydraulic tunnel of horseshoe cross-section caused by the internal head of water. Research objectives: determination of real values of circumferential stresses along the development contour. Materials and methods: solution of the problem of plane deformation of the theory of elasticity for a transversely isotropic medium containing tunnel excavation cannot be obtained by analytical methods, and therefore the stress-strain analysis was carried out by the finite element method using the ANSYS software package, MCE. Results: determination of stresses along the development contour, construction of diagrams and graphs showing the effects of the anisotropy conditions and Poisson’s ratio. The tangential stresses along the contour of hydraulic tunnel development for various values of deformation modulus and Poisson’s ratio are determined, which makes it possible to estimate the strength of the rock mass for different tunnel depths. The analysis of a long hydro-technical tunnel, laid in a strong, transversally isotropic rock, is reduced to the problem of plane deformation of the theory of elasticity for a transversely isotropic medium containing tunnel excavation. The size and type of the finite element suitable for analysis were determined in advance based on the solution of the test problem. Conclusions: it is necessary to determine the physical and mechanical properties of rocky soils more accurately, paying special attention to elastic characteristics; calculations should be performed taking into account the anisotropy of elastic properties.

DOI: 10.22227/1997-0935.2017.10.1172-1179