7 research outputs found
An Attempt at Evaluation of the Remnant Influence On the Occurrence of Seismic Phenomena in a Room-and-Pillar Mining System with Roof Deflection
No full textAbstract
Experience gained until now underground mining worldwide and in Poland indicates that remnants may have an impact on the occurrence of seismic phenomena. Remnants are stress concentration sites encompassing both the deposit and the layers of rock mass located above and below the undisturbed rock. In the case where stresses in the remnant exceed its strength, it may collapse, and under unfavourable geomechanical conditions, stress-induced rockburst may occur. Remnants may also cause breaking of strong roof layers above their edges, which results in the occurrence of high-energy shocks (Salustowicz [30], Adach [3], Adach and Butra [4]). This article presents the possibility of utilizing numerical modeling to evaluate the influence of remnant upon the occurrence of seismic phenomena. The results of numerical calculations performed for a model room-and-pillar mining system with roof deflection under the conditions of copper ore mines in the Legnica-Głogów Copper District (LGOM) are presented. Numerical calculations in a plane strain state were performed by means of Phase2 v. 8.0 software for the analyzed mining system in which remnant was left behind. The results of numerical modeling showed that sudden fracturing of roof layers above the mined out space may occur on the edge of the remnant. This may cause a shock with very high energy, and under the appropriate conditions, this may lead to the rockburst phenomenon.</jats:p
Eksploatacja złoża w sąsiedztwie zrobów i stref upodatnionych w świetle doświadczeń praktycznych oraz modelowania numerycznego
No full textTyt. z nagłówka.Bibliografia s.112.Dostępny również w formie drukowanej.STRESZCZENIE: Na podstawie analizy dotychczasowych doświadczeń oraz wyników modelowania numerycznego przedstawiono zagadnienie zagrożenia tąpaniami i zawałami w przypadkach prowadzenia rozcinki w kierunku zrobów i stref upodatnionych. SŁOWA KLUCZOWE: modelowanie numeryczne, strefy upodatnione, eksploatacja rud miedzi. ABSTRACT: Bump and roof fall hazard potential is assessed based on the practical observations and numerical (FEM) modeling of mining operations conducted near the already mined-out and/or yielding zones. KEYWORDS: numerical modelling, yelding zones, copper ore exploitation
Ocena zagrożenia tąpaniami i profilaktyka tąpaniowa w polskich kopalniach miedzi
No full textLongstanding mining of copper deposit in the Legnica-Glogow Mining Basin (LGOM area) enabled to gain broad experience concerning the impact of geological and mining conditions on seismic and rockburst hazard. Basing on gathered data, the methods of rockburst prevention for deep copper mines were developed. Methods of rockburst hazard evaluation as well as rockburst control methods constitute a set of rockburst prevention. The prevention methods due to their nature and location within the production process can be the passive and the active ones. Active methods of rockburst prevention consist in liquidation of stresses in the areas of their concentration through controlled generation of rock-mass tremors and rockburst by blasting works (group winning blasting, release blasting in rock-mass and in pillars able to accumulate the stress as well as in the roof and floor). Whereas the group blasting works as a basic method are very effective in the copper mines conditions. Provocation of dynamic events makes possible the control of time of their occurrence. In Polish copper mines all blasting works are made during the absence of miners in the mining fields. Daily distribution of both the number of recorded strong seismic events and the volume of energy released confirm the advisability of using this kind of rockburst hazard prevention. The rockburst hazard prevention methods developed during the 40 years of copper deposit extraction are economically reasonable and offer the sufficient effectiveness under the high rockburst hazard conditions.Czasopismo Cupru
Numerical Methods as an Aid in the Selection of Roof Bolting Systems for Access Excavations Located at Different Depths in the LGCB Mines
No full textThe values of primary stresses are not allowed for as a criterion in the selection of roof bolting systems in mining excavations located at various depths in Polish copper ore mines. Therefore, in order to ensure enduring and safe operation of excavations, in particular, those driven in unfavourable geological and mining conditions, this problem has required solutions based on numerical methods. This article presents an example of applying numerical simulations to the evaluation of the stability of headings in Polish copper ore mines. The analyses included mining excavations located at various depths in the rock mass. This issue is of great importance, as safety regulations are prioritised in mining excavations which remain in operation even for several decades. The stability of the headings was evaluated with the use of the RS2 specialist numerical simulation software. This computer program uses the finite element method (FEM) for calculations. The rock parameters used in the numerical models have been determined on the basis of the Hoek–Brown classification. For that purpose, the RocLab 1.0 software was used. The parameters of the stress field were identified from the profile of the GG-1 shaft with the assumed hydrostatic state of stress. The numerical modelling was performed in a triaxial stress state and in a plane strain state. The numerical analyses were based on the Mohr–Coulomb failure criterion. The rock medium was described with the elastic-plastic model with softening (roof and walls) and with the elastic-plastic model (floor). The results of the numerical analyses served to provide an example of the application of a roof bolting system to protect headings located at the depths of 1000 m b.g.l. and 1300 m b.g.l
Analiza dokonanej eksploatacji oraz sposobu dalszego prowadzenia robót eksploatacyjnych w polu G-7/5 O/ZG "Rudna"
No full textTyt. z nagłówka.Pozostali autorzy art.: Rafał Dębkowski, Zdzisław Iwulski, Marcin Szpak.Bibliogr. s. [128].Dostępny również w formie drukowanej.STRESZCZENIE: Scharakteryzowano warunki geologiczno-górnicze prowadzonej eksploatacji, występujące w rejonie pola G-7/5. Opisano przebieg robót górniczych od momentu rozpoczęcia eksploatacji w 2002 r. Przeanalizowano wyniki prowadzonych badań i obserwacji zachowania się górotworu oraz dokonano oceny stanu zagrożenia sejsmicznego w polu. Złoże rud miedzi w polu G-7/5, zlokalizowane jest na głębokości około 870 m, w skrzydle wiszącym uskoku "Biedrzychowa". W polu wydzielono trzy bloki eksploatacyjne. Bardzo trudne warunki geologiczno-górnicze w polu, zwłaszcza w bloku "A", powodowały wielokrotne zmiany kierunku prowadzenia robót, w tym na zroby i strefy upodatnione. Obecnie prowadzone są roboty likwidacyjne w bloku "A" i roboty rozcinkowe w bloku "B", które uruchomiono w sierpniu 2010 roku. Ze względu na poziom aktywności można wyróżnić trzy okresy podczas prowadzonej eksploatacji od października 2009 do września 2010 roku, które odpowiadają specyfice prowadzonych robót wybierkowych oraz stosowanej profilaktyce zagrożenia sejsmicznego. Lokalizacja ognisk silnych wstrząsów wskazuje, że większość z nich występowała w liniach uskoków, przebiegających przez strefę roboczą pola G-7/5 oraz na krawędziach prowadzonej rozcinki złoża. Dotychczasowej eksploatacji towarzyszył stosunkowo wysoki poziom zagrożenia tąpaniami i zawałami, głównie ze względu na zaangażowanie tektoniczne. SŁOWA KLUCZOWE: górnictwo podziemne, metody obserwacji i pomiarów, ocena stateczności górotworu. ABSTRACT: In the paper geological and mining technology conditions in "G-7/5" panel of Rudna Cooper Mine was described. The mining process started in 2002 is presented as well. The results of rock mass observations and measurements were characterized and seismic hazard in "G-7/5" panel was evaluated. Ore body in "G-7/5" panel is located at a depth of 870 m in the downthrown side of "Biedrzychowa" fault. "G-7/5" panel is composed of three smaller excavation blocks. Hard geological and mining conditions in this panel, especially in block "A", often result in mining direction changes e.g. toward old workings and yielding zones. At present in block "A" liquidation works are carried out. In block "B" face-entry drivage was started in August 2010. Depending on activity level, during mining in that area between October 2009 and September 2010, three different periods can be distinguished. They correspond with the specific character of mining works and prevention methods against seismic activity hazard. Location of mining tremors indicate that many of them occurred in faults lines running through the working area in "G-7/5" panel and on the block development edges. Due to tectonic dislocations in this area, mining in "G-7/5" panel was connected with relatively high level of bumps and roof falls hazard. KEYWORDS: underground mining, observations and measurements methods, rating of rock mass stability
The effect of primary stress on underground excavations stability
No full textPrzedstawiono problematykę wpływu wzmożonych naprężeń pierwotnych na stateczność wyrobisk górniczych. Opisano stosowane w górnictwie światowym sposoby poprawy stateczności wyrobisk kopalnianych, wykonywanych w polu wzmożonych naprężeń poziomych.Czasopismo Cupru
