Preiskave vpliva toplotno energetskih polj na lastnosti zemljin

This paper describes details of a study to investigate and demonstrate the changes undergone by soil when it is exposed to elevated temperatures. Such situations are commonly encountered while designing the foundations for the furnaces, boiler units, forging units, brick kilns, rocket launching pads, buried power-supply cables, air-conditioning ducts, underground explosions, disposal of high-level radioactive and industrial toxic wastes, ground modifications or soil-stabilization techniques, etc. As such, investigations to establish changes undergone by the soil when it is exposed to elevated temperatures assume some importance. With this in view, individual samples of six soils, with entirely different characteristics, were subjected to temperatures up to 300°C (sequentially in steps of 50°C) and after each step of thermal treatment, these samples were characterized for their physical, chemical and mineralogical properties. Based on a critical synthesis of the results, it has been demonstrated that elevated temperatures cause (i) a change in the color, (ii) an increase in the specific gravity, particle size and weight loss, (iii) a reduction in the specific surface area, cation-exchange capacity and zeta-potential, and (iv) a structural transformation of the soil. Though these changes would affect the engineering properties of the soil to a large extent, the scope of this paper is limited to demonstrating the alterations in physical, chemical and mineralogical changes, only, occurring in the soil when it is exposed to elevated temperatures.Članek opisuje podrobnosti študije o preiskavah zemljin in njihovih spremembah pri povišanih temperaturah. Do takšnih situacij pride običajno pri načrtovanju temeljev za peči, kotle, naprave za kovanje, opekarne, izstrelitvene ploščadi, pri polaganju podzemnih napajalnih kablov in klimatizacijskih vodov, pri podzemnih eksplozijah, odlaganju visoko radioaktivnih in strupenih industrijskih odpadkov, modifikaciji in stabilizaciji zemljin itd. V takih primerih je pomembno opraviti preiskave za določitev sprememb, ki so jim podvržene zemljine pri izpostavljanju povišanim temperaturam. V preiskavi so bili posamezni vzorci šestih zemljin s popolnoma različnimi lastnostmi izpostavili temperaturi do 300°C (v zaporednih stopnjah po 50°C), po vsaki končani stopnji termične obdelave pa so bile določene njihove fizikalne, kemične in mineraloške lastnosti. Na osnovi kritične sinteze rezultatov je pojasnjeno, da povišane temperature povzročijo (i) spremembo barve, (ii) povečanje specifične teže, velikosti delcev in izgubo teže, (iii) zmanjšanje specifične površine, sposobnosti kationske izmenjave in zeta potenciala in (iv) strukturne spremembe zemljin. Čeprav bi te spremembe močno vplivale na inženirske lastnosti zemljin, je obseg tega članka omejen zgolj na prikaz fizikalnih, kemičnih in mineraloških sprememb zemljin, ki se pojavijo pri izpostavljanju zemljin povišanim temperaturam