Ugotavljanje kvalitete zapolnjevanja jamskih prog s pomočjo ročnega georadarja

Skaza, Valentin (author), Rošer, Janez (mentor)

V Premogovniku Velenje se za potrebe pridobivanja premoga izdelujejo dostopne proge v premoškem sloju. Podgradnjo sestavljajo jekleno ločno podporje (JLP) in leseni opaž, ki se namesti za ločnim podporjem, ki poleg dodatne nosilnosti podgradnje preprečuje rušenje premoga v progo. Pri potovanju zraka skozi razrušen premog, prihaja do oksidacije, pri čemer se sprošča toplota. Če ta proces poteka dalj časa, je rezultat samovžig premoga oz. jamski požar. V izogib tega se izdeluje izolacijski plašč po obodu proge, ki pa dodatno poveča tudi nosilnost celotnega sistema podgradnje. Temelji na tem, da se prostore med podgradnjo in premogom zapolni z mešanico elektrofiltrskega pepela, cementa in vode. Zapolnjevanje poteka skozi cevi, ki so vgrajene v stropni del proge. Polnilo teče od vrha po obodu proge navzdol. Voda, ki ne ostane v polnilu se izloči in za sabo pusti praznine. Preverjanje kvalitete zapolnjevanja izolacijskega plašča se izvaja z vrtanjem skozi opaž s pnevmatskim strojčkom Turmag in spiralnim svedrom. Kvaliteta se ugotavlja z opazovanjem iznesenega materiala in upora pri vrtanju. Pomanjkljivost tega je, da se kvaliteta preverja na naključnih točkah, pri tem pa se poškoduje del izolacijskega plašča. S prihodom ročnega georadarja na tržišče se je porajalo vprašanje ali je naprava primerna za ugotavljanje kvalitete izdelave izolacijskega plašča. Ta elektromagnetna geofizikalna metoda je primerna zaradi preproste izvedbe meritev ter nedestruktivnosti procesa. Naprava oddaja EM valove ter sprejema njihove odboje od objektov z različnimi dielektričnimi lastnostmi. Izvedeno je bilo testiranje naprave v jami na treh lokacijah. Pri izmeri smo se srečali z operativnimi težavami zaradi razgibanega profila jamske proge, kjer je premikanje georadarja oteženo. Pridobljeni rezultati meritev niso podali jasnega odgovora na vprašanje uporabnosti. Zato je bil izveden še dodatni preizkus na lesenih zabojih, ki so bili narejeni za posnemanje pogojev v jami. Zaboj A je bil zapolnjen s premogom v celoti, sledila je plast polnila, opaž in JLP. Za primerjavo pa je zaboj B vseboval dve praznini v sloju premoga in eno praznino v plasti polnila. Pri dodatnem poskusu smo ugotovili, da s testiranim georadarjem praznin v zabojih ni moč zaznati.. Vzrok za to so karakteristike JLP, ki ne prepušča elektromagnetnih valov. Po odstranitvi JLP in opaža je bila praznina v polnilu jasno razvidna. Preostalih dveh praznin, ki sta se nahajali na dnu zaboja, nismo prepoznali. Verjetni vzrok za to je zasičenost polnila in premoga z vodo, ki ovira izmero z georadarjem. Rezultati preizkusov so pokazali, da naprava s podanimi zmogljivostmi ni primerna za izvajanje kontrole izdelave izolacijskega plašča.

• Language: Slovenian
• Keywords: georadar, Premogovnik Velenje, kvaliteta izdelave jamskih prog
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2019
• PID: 20.500.12556/RUL-110955
• COBISS.SI-ID: 1838431
• Publication date in RUL: 21.09.2019

Secondary language

• Language: English
• Title: Determining the filling procedure quality in case of mining roadways with handheld GPR

Abstract

For the purpose of coal extraction in Velenje Coal Mine mining roadways are being built. They are composed of Steel arch support (SAS) and wooden panelling which is installed behind the steel arches, which in addition to the higher load-bearing capacity of the support, prevents coal falling into the roadway. When the air current moves through fractured coal layer, oxidation process is causing heat discharges. If this process continues for a longer period it can lead to self combustion of coal and consequently to mine fire. To prevent this problem, an insulation coating is applied on the rim of the roadway. The coating also improves the load capacity of the support. The main goal is to fill the space between the coal seam and wooden panelling with a mixture of fly ash, cement and water. The filling procedure starts by installing the pipes in the roof of the roadway. The filling mixture is then pumped through the pipes and flows to the bottom of the roadway. After the filling is completed the excess water flows away, leaving voids in the insulating layer. Determining the quality of the filling procedure is done by drilling holes into the insulating layer. Drilling takes place on random points and is done with pneumatic drilling machine Turmag and spiral drill. During the drilling attention to the cutting’s composition and drilling resistance must be paid. The downside of drilling is the damaging of the insulation layer. With new handheld GPR on the market a question if this method is suitable for determining the quality of filling procedure arose. This electromagnetic geophysical method is suitable because of non-destructive and easy surveying. The device emits electromagnetic waves and receives reflections from objects with different dielectric properties. The test took place on three locations in the coal mine. Because of the diverse roadway surface, we had difficulties during surveying. The gathered results didn't show a clear proof if the device is usable. Therefore a second test was done on the wooden boxes which were made to replicate the mining roadway. The A box was filled with a layer of coal, above it was a layer of filling and on top the wooden panelling with SAS. The B box had two voids in the coal layer and one void above it. No voids were found in the GPR testing. We assume that this is due to the SAS which blocks the incoming electromagnetic waves. After removing the SAS and wooden panelling the void on top of coal was easily recognised. The other two voids in the coal layer weren’t recognised at all. The probable cause of this is water in the saturated coal and filling layer which also disables surveying with GPR. The results of tests have shown, that this kind of handheld GPR is not suitable for determining the filling quality of insulation coating.

• Keywords: GPR, Premogovnik Velenje, mining roadways construction quality