Immediate Roof Stability Analysis for New Roomand- Pillar Mining Technology in “Estonia” Mine

Abstract

This paper analysis the immediate roof (IR) stability by the deformation criteria for new room-andpillar mining technology with modern machines in “Estonia” mine. The new mining technology based on a blasting method to move from packaged to emulsion explosives, from 2.0 m to 4.0 m boreholes (FRANZ SCHELL machine) and on new undercutting (SMAG machine) method. With such equipped new technology the entry advance rates reached 3.8 m. As a result of such greater advance rates the situations with unsupported room length up to 5.5 m with decreasing the stability of IR can be expected. The analysis of IR stability based on an in-site underground testing by the leaving bench-mark stations and convergence measurements. The main targets of this study to determine the main parameters for supported/unsupported IR deformation in areas with great entry advance rates and risk analysis concept elaboration.

Analysis of Earthquakes Available Influence on „estonia” Mine Underground Construction Stability

“…The available influence o f pillars deformation on modelled roof was not taken into account. By data of analyzed exfoliation levels the roof plate thickness h =1.0 m was accepted [14]. For the FEM modelling demo version o f "FEMmodels" software was used [13].…”

Risk assessment of seismic impact on the roof and pillars stability in Estonian underground

“…factors that present difficulties for finding the dependence ( ). f t ε = During on-site testing 16 pairs of BMS were installed and 19 holes were viewed by the stratascope in two mining blocks (3103 and 3104) with different geological conditions (with weak and average stable IR)[ 5 ]. The results of IR Roof-to-floor convergence curve by VNIMI and IGD data (a) and typical curve for the longterm stability analysis (b) [ 3 ]: t -time; t p = t 3 -time at failure; ε -deformation; ε u -ultimate deformation at failure; ε e -elastic deformation; I -elastic deformation ε e ; II -transient creep έ < 0 (έ -deformation rate); III -steady-state creep (έ = const); IV -transient creep (έ > 0).…”