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

Vestnik MGSU 10/2017 Volume 12
  • Bautdinov Damir Tahirovich - Russian State Agrarian University - Moscow Timiryazev Agricultural Academy (RSAU - MTAA or RSAU - MAA named after K.A. Timiryazev) Candidate of Technical Sciences, Associate Professor, Department of Technical Mechanics and Construction, Russian State Agrarian University - Moscow Timiryazev Agricultural Academy (RSAU - MTAA or RSAU - MAA named after K.A. Timiryazev), 49 Timiryazevskaya str., Moscow, 127550, Russian Federation.
  • Atabiev Umar Ishakovich - Russian State Agrarian University - Moscow Timiryazev Agricultural Academy (RSAU - MTAA or RSAU - MAA named after K.A. Timiryazev) Postgraduate, Department of Hydro-technical Construction, Russian State Agrarian University - Moscow Timiryazev Agricultural Academy (RSAU - MTAA or RSAU - MAA named after K.A. Timiryazev), 49 Timiryazevskaya str., Moscow, 127550, Russian Federation.

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

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Problematics of stress-strain state research in units of metal structures

Vestnik MGSU 5/2014
  • Morozova Dina Vol'demarovna - Moscow State University of Civil Engineering (MGSU) Candidate of Technical Sciences, Associate Professor, Senior Researcher, Department of Architectural and Structural Design, Moscow State University of Civil Engineering (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
  • Serova Elena Aleksandrovna - Moscow State University of Civil Engineering (MGSU) postgraduate student, Department of Architectural and Structural Design, Moscow State University of Civil Engineering (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 44-50

The article describes the experimental methods of determining stress-strain state of elements and structures with a brief description of the essence of each method. The authors focus mostly on polarization-optical method for determining stresses in the translucent optical sensing models made of epoxy resins. Physical component of the method is described in the article and a simple diagram of a circular polariscope is presented, as well as an example of the resulting interference pattern in illuminated monochromatic light. A polariscope, in its most general definition, consists of two polarizers. The polarizers sandwich a material or object of interest, and allows one to view the changes of the polarity of light passing through the material or object. Since we are unable to perceive the polarity of light with the naked eye, we are forced to use polariscopes to view the changes in polarity caused by the temporary birefringence of our photoelastic materials. A polariscope is constructed of two polarizers, each set perpendicular to the path of light transmitted through the setup. The first polarizer is called the "polarizer", and the second polarizer is called the "analyzer". The method how the polarizer works is quite simple: unpolarized light enters the polariscope through the polarizer, which allows through only the light of its orientation. This light then passes through the material under observation, and experiences some change in polarity. Finally, this light reaches the analyzer, which, like the polarizer, only lets the light of its orientation through.

DOI: 10.22227/1997-0935.2014.5.44-50

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