THE EFFECT OF TEMPERATURE ON THE PHYSICO-MECHANICAL CHARACTERISTICS OF CHALK

The effect of temperature on the physical and mechanical characteristics (modulus of elasticity and density) of the chalk samples with natural structural links with the natural moisture content equal to 14% is considered. More than 30 samples that were subjected to the effects of temperature for 30 minutes in the chamber of heat and cold KTH at the natural temperature range (-30 to +40 °C ± 2°), typical for the areas of chalk development in Belgorod region are prepared and tested. Methods of sample preparation and determination of density, moisture and elastic modulus are given. The experimental results are presented. The relative changes in physical and mechanical characteristics from the temperature are extreme in nature and are well approximated by polynomial functions of the second order. The approximation reliability is 0,87–0,93 for the density and elastic modulus, respectively. The test results are processed by the program «ASIS Report». Analysis of changes in the density and elastic modulus (Young’s modulus) of samples depending on the temperature factor exposure is given. It is found that significant changes in elastic modulus are observed at relatively small changes in density. The lowest values of the elastic modulus are characteristic for the temperature 0 °C, and they are equal to 410 MPa. The highest values of the elastic modulus are characteristic for negative temperatures. At a temperature of -30 °C with the natural humidity from 13 to 14%, it increases to 99% and exceeds the value of 800 MPa, which is associated with the formation of cryogenic structural connections in the rock. At 30 °C the elastic modulus is increased by 27%, which at 40 °C reaches 640 MPa (56%). This is related to hardening of the structural links between rock particles by evaporation of moisture from it. The obtained dependences allow us to understand the mechanisms of the changes occurring in the rock under the influence of variable physical fields and to take into account their impact in the development of chalk deposits.

Keywords

Chalk, development of deposits, rock destruction, temperature factor, modulus of elasticity, density, natural moisture.

Issue number: 2
Year: 2017
ISBN:
UDK: 622.02:531
DOI:
Authors: Ermolovich E. A., Ovchinnikov A. V.

About authors: Ermolovich E.A., Doctor of Technical Sciences, Professor, Assistant Professor, e-mail: elena.ermolovich@mail.ru, Ovchinnikov A.V., Senior Lecturer, e-mail: ovchinnikov@bsu.edu.ru, Belgorod State National Research University, 308015, Belgorod, Russia.

REFERENCES:
1. O sostoyanii i ispol’zovanii mineral’no-syr’evykh resursov Rossiyskoy Federatsii v 2013 godu: Gosudarstvennyy doklad. Pod red. D. G. Khramova (The state and utilization of mineral reserves in the Russian Federation in 2013: Government Report. Khramov D. G.), Moscow, Ministerstvo prirodnykh resursov RF, 2014, 384 p.
2. Rzhevskiy V. V., Novik G. Ya. Osnovy fiziki gornykh porod: uchebnik dlya vuzov. 4-e izd. Fundamentals of physics of rocks: Textbook for high schools, 4th edition), Moscow, Nedra, 1984, 359 p.
3. Tangaev I. A. Energoemkost’ protsessov dobychi i pererabotki poleznykh iskopaemykh (Energy content of mineral mining and processing operations), Moscow, Nedra, 1986, 231 p.
4. Kurilko A. C. Eksperimental’nye issledovaniya vliyaniya tsiklov zamorazhivaniya-ottaivaniya na fiziko-mekhanicheskie svoystva gornykh porod (Experimental research of effects of freezing–thawing cycles on physico-mechanical properties of rocks), Yakutsk, Izd-vo SO RAN, 2004, 153 p.
5. Zakharov E. V. Vliyanie znakoperemennykh temperaturnykh vozdeystviy na energoemkost’ protsessa drobleniya gornykh porod (Alternating temperature effects on energy content of rock crushing), Candidate’s thesis, Yakutsk, 2012, 120 p.
6. Brotóns V., Tomás R., Ivorra S., Alarcón J. C., 2013, Temperature influence on the physical and mechanical properties of a porous rock: San Julian’s calcarenite. Engineering Geology. 2013. Vol. 167. pp. 117–127.
7. Xian Biao Mao, LianYing Zhang, Ai Hong Lu Experimental study on the mechanical properties of rocks at high temperature. Science in China Series E: Technological Sciences. 2009. Vol. 52, Issue 3, pp. 641–646.
8. Rutter E. H. The influence of interstitial water on the rheological behaviour of calcite rocks. Tectonophysics. 1972. Vol. 14 (1), pp. 13–33.
9. Rutter E. H. The influence of temperature, strain rate and interstitial water in the experimental deformation of calcite rocks. International Journal of Geotectonics and Tectonophysics. 1974. Vol. 22, pp. 311–334.
10. Ermolovich E. A., Ovchinnikov A. V. Sotsial’no-ekonomicheskie i ekologicheskie problemy gornoy promyshlennosti, stroitel’stva i energetiki: Materialy 11 Mezhdunarodnoy konferentsii. Pod red. R. A. Kovaleva (Social, Economic and Environmental Problems in Mining, Construction and Power Engineering: The 11th International Conference Proceedings. Kovalev R. A. (Ed.)), Tula, TulGU, 2015, pp. 180–183.
11. Grunty. Metody laboratornogo opredeleniya kharakteristik prochnosti i deformiruemosti. GOST 12248-2010 (Soils. Methods of laboratory testing of strength characteristics and deformability. State Standart 12248-2010), Moscow, MNTSK, 2011, 156 p.
12. Boldyrev G. G. Metody opredeleniya mekhanicheskikh svoystv gruntov. Sostoyanie voprosa (Methods to determine mechanical properties of soil. State-of-the-art), Penza, PGUAS, 2008, 696 p.
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