### Geological background of the estimation of natural stresses in soil body

Pages 44-53

Initial and boundary conditions are always given for solving the problem of calculating the interaction of tunnels and other underground structures with soil and rocks. The same conditions are set for calculating the surface buildings. These initial data for calculation are divided into three groups: 1) the geometrical shape of the layers of rocks (geological structure); 2) the parameters of the strength and compressibility of rocks; 3) compressive stresses in the array. These data all over the world are set with engineering surveys. In engineering surveys there are good methods of determining the source of the data 1 and 2. But there is no available methodology for determining the natural stress state. Therefore, compressive and tensile stresses are usually determined by mathematical modeling. The calculation of the compressive stresses is done on the basis of the following hypotheses: compressive stresses are created by the weight of rocks; they go down in proportion to the density of rocks; the main normal stress is has a vertical direction; normal stress in horizontal direction is smaller. The value of the horizontal stress is was calculated using Poisson’s ratio. This hypothesis of the nineteenth century was used another 50 years ago, when it was not known exactly about the movement of the continents and when compressive stresses in the earth’s crust have not yet been measured. Today a universal application of this hypothesis is not correct. Now the application of this hypothesis in many cases is not correct. In this research paper an attempt is made to specify the area, in which the above hypothesis can be used. This is done on the basis of current scientific evidence. Abroad this way of calculating tunnels and other underground structures and bases of buildings should be done taking into account the real field of natural stresses. The geological characteristics of the location of the axes of stresses in soil body are based on the study of fractures. Also the article shows the influence of the surface topography of the territory on stress in soil. In order to draw conclusions the author uses his observations of the construction in Siberia and Mongolia, as well as publications of other scientists. The author notes that in engineering surveys for construction of tunnels, high-rise dams, high rise buildings there is no good method of determining the natural stresses in rocks and soils, which is equal in accuracy to the methods of construction of geological sections and methods for determining the estimated characteristics of the soil. This gap needs to be filled. The possible direction of work is: to combine the methods of direct measurements of compressive stresses with indirect geophysical methods and computer modeling.

DOI: 10.22227/1997-0935.2015.1.44-53

- Suppe J. Fluid Overpressures and Strength of the Sedimentary Upper Crust. Journal of Structural Geology. December 2014, vol. 69, part B, pp. 481—492. DOI: http://dx.doi.org/10.1016/j.jsg.2014.07.009.
- Nesterenko G.T., Barkovskiy V.M. O vozmozhnosti otsenki napryazhennogo sostoyaniya zemnoy kory po naturnym izmereniyam napryazheniy v shakhtakh i rudnikakh [On the Possibility of Estimating the Stress State of the Crust in Situ Measurements of Stress in Mines]. Napryazhennoe sostoyanie zemnoy kory : sbornik trudov [Stress State of the Earth Crust : Collection of Works]. Moscow, Nauka Publ., 1973, pp. 12—20. (In Russian)
- Kutepov V.M. Zakonomernosti v raspredelenii estestvennykh napryazheniy v massivakh skal’nykh treshchinovatykh porod sklonov rechnykh dolin [Regularities in the Distribution of Natural Stresses in the Hard Fractured Rocks of the Slopes of River Valleys]. Napryazhennoe sostoyanie zemnoy kory : sbornik trudov [Stress State of the Earth Crust : Collection of Works]. Moscow, Nauka Publ., 1973, pp. 135—147. (In Russian)
- Kropotkin P.N. Tektonicheskie napryazheniya v zemnoy kore po dannym neposredstvennykh izmereniy [Tectonic Stresses in the Earth’s Crust According to Direct Measurements]. Napryazhennoe sostoyanie zemnoy kory : sbornik trudov [Stress State of the Earth Crust : Collection of Works]. Moscow, Nauka Publ., 1973, pp. 21—31. (In Russian)
- Pashkin E.M., Kagan A.A., Krivonogova N.F. Terminologicheskiy slovar’-spravochnik po inzhenernoy geologii [Terminological Dictionary on Engineering Geology]. Moscow, KDU Publ., 2011, 950 p. (In Russian)
- Ter-Martirosyan Z.G., Akhpatelov D.M. Napryazhennoe sostoyanie gornykh massivov v pole gravitatsii [Stress State of Mountain Ranges in the Field of Gravity]. DAN SSSR [Proceedings of the USSR Academy of Sciences]. 1975, vol. 220, no. 2, pp. 1675—1679. (In Russian)
- Kalinin E.V., Panas’yan L.L., Shirokov V.N., Artamonova N.B. Modelirovanie poley napryazheniy v inzhenerno-geologicheskikh massivakh [Modeling Stress Fields in Engineering Geological Bodies]. Moscow, MGU Publ., 2003, 261 p. (In Russian)
- Wan Guillong. Modeling Field Tectonic Stresses the East Wing Tectonic Belt Badahan in Northern China Tektonic Era. Dixue gionyuan = Earth Sci. Front. 2012, vol. 19, no. 6, pp. 194—199. Chinese. CV Eng.
- Xia C., Gui Y., Wang W., Du S. Numerical Method for Estimating Void Spaces of Rock Joints and the Evolution of Void Spaces under Different Contact States. Journal of Geophysics and Engineering. December 2014, vol. 11, no. 6, article number 065004. DOI: http://dx.doi.org/10.1088/1742-2132/11/6/065004.
- Osipov V.I., Medvedev O.P., editors. Moskva. Geologiya i gorod [Geology and a City]. Moscow, Moskovskie uchebniki i kartolitografiya Publ., 1997, 400 p. (In Russian)
- Chernyshev S.N. Treshchiny gornykh porod [Rock Fractures]. Moscow, Nauka Publ., 1983, 240 p. (In Russian)
- Chernyshev S.N., Dearman W.R. Rock Fractures. Butterworth-Heinemann, London, UK, 1991, 272 p.
- Haines S., Marone C., Saffer D. Frictional Properties of Low-Angle Normal Fault Gouges and Implications for Low-Angle Normal Fault Slip. Earth and Planetary Science Letters. December 2014, vol. 408, pp. 57—65. DOI: http://dx.doi.org/10.1016/j.epsl.2014.09.034.
- Konyarova L.P. Opyt obobshcheniya massovykh opredeleniy pokazateley vodopronitsaemosti treshchinovatykh skal’nykh porod [Statistical Summary of Mass Estimations of the Permeability of Fractured Rocks]. Inzhenerno-geologicheskie svoystva gornykh porod i metody ikh izucheniya : sbornik trudov [Engineering and Geological Properties of Rocks and Methods of Their Research : Collection of Works]. Moscow, AN SSSR Publ., 1962. (In Russian)
- Beloyy L.D., editor. Otsenka tochnosti opredeleniya vodopronitsaemosti gornykh porod [Estimating Determination Accuracy of Rock Permeability]. Moscow, Nauka Publ., 1971, 150 p. (In Russian)