An Attempt at Evaluation of the Remnant Influence On the Occurrence of Seismic Phenomena in a Room-and-Pillar Mining System with Roof Deflection

Abstract

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.

Investigation of the Impact of Natural Fracture Geomechanics on the Efficiency of Oil Production and CO2 Injection from/to a Petroleum Structure: A Case Study

“…Defining the variogram parameters helped interpolate modeled parameters to reproduce realistic distributions of given parameters in the 3D grid. The examples of the 3D models of Poisson's ratio, Young modulus, and uniaxial compressive strength are shown in Figure 4A,D, Figure 4B,E Based on the literature cited below, we assumed the values of other geomechanical properties of the overlying strata which are required for geomechanical simulations [78][79][80][81][82]. The assumed values of geomechanical properties used in geomechanical simulations are listed in Table 1.…”

Analysis of Caprock Tightness for CO2 Enhanced Oil Recovery and Sequestration: Case Study of a Depleted Oil and Gas Reservoir in Dolomite, Poland

“…The 3D distribution of the tensile strength was obtained in a similar manner as the 1D models, wherein Hoek's relationship with UCS was utilized. Other geomechanical parameters, such as friction angle, angle of dilatation, and the Biot's coefficient, were assigned based on the typical values for appropriate lithologies listed in the literature [32][33][34][35][36]. The properties used as an input in the geomechanic modelling, both as a result of the modelling procedure and assumed based on the literature, are listed in Table 1.…”

Fast, non-destructive measurement of roof-bolt loads

“…The relationship (1) indicates that the change in the rate of wave propagation, and -by extension -in the time of wave propagation between the transmission and reception head influences the frequency of the self-excited system. Moreover, the SAS has another advantage of featuring a positive feedback loop, allowing the frequencies of the measurement system to amount to several dozen kHz instead of MHz.…”

“…Among the many factors affecting the stability of mine workings, the most notable include rock bursts, [4,19] faults, [2,14,25] potential rock bursts under abandoned workings [3] and the size of stoops. [1] State mining authorities also play a special role in improving the occupational health and safety conditions in mining. [7] When independent roof bolting is used in a rock that has the potential to generate seismic energy, the amount of energy absorbed by such bolting should be determined.…”