Rock support systems have become widely dominant components in underground hard rock mines. The use of rmi in design of rock support in underground openings. Many of the earlier attempts to characterize ground stability and prevent premature roof failures were based on rockmass characterization, entry size, support design, and ground water inlux. Support of underground excavations in hard rock is the most complete and uptodate manual for use in the design of excavations and support mechanisms for underground mines. Pillar stability experiment and aecls mineby experiment. The results were compared to recommended support requirements based on. Stability of mining openings requires consideration of a number of factors, such as.
The first two sections summarize some of the current knowledge on stability and failure modes in underground openings. One of the consequence is that a decrease in stress may reduce the critical excavation span. The strength of the rock depends on geology, and the loads are applied primarily by the in situ and mininginduced stresses. Support of underground excavations in hard rock mirarco. Empirical methods rely on estimations of the effect of key geotechnical parameters to build a roof stability model which can then be used to design mine openings and prescribe roof support. The term stability index for the assessment of underground mine openings tunnels. Phase2 is a 2dimensional finite element program that calculates stresses and displacements around underground openings. Influence of stope design on stability of hanging wall. Department of industry and resources geotechnical considerations in underground mines document no zme723qt guideline issued. Blasting is an integral part of underground mining operations, as this is the beginning of the cycle that leads to the extraction of valuable materials the reason for the existence.
The actual performance of largediameter raisebored shafts is also compared to empirical stability assessments. In this research, phase2 software has been used to perform stability analysis and to suggest a support system for the tunnel in question. The potential for instability in the rock surrounding underground mine openings is an everpresent threat to both the safety of men and equipment in the mine. In order to address these issues, an assessment must be made of. The purpose of this chapter is to show the use of the rmi in stability analysis and rock support estimates for underground excavations. The term stability index for the assessment of underground mine openingstunnels. Geotechnical considerations in underground miningdepartment of industry and resources guideline document no zme723qt 1. Minto mine mine development and operations plan the foliated granodiorite zones themselves are highly variable in the content of their mineralization. Stability assessment of old underground coal mine openings. An investigation into the standup time of stopes at the.
Field observations at this mine were integrated with roof fall risk index rfri mapping. One of those alternatives is the coating of timber with a fireretardant which provides a flame spread rating of 25 or less. The potential for instability in the rock surrounding underground mine openings is an. Other factors, such as wider spans and retreat or multipleseam mining, can also reduce the stability of mine openings. Stability and support issn book 40 kindle edition by aldorf, j. This is more so for deep excavations which may be under significantly high stresses. Stability of underground openings is a major concern for the safety and productivity. This paper presents the stability assessment of a century old coalmine situated under a railway track. The classification of these methods, based on the analysis of factors determining the behaviour of a system of mine openings, should contribute to the greater objectivity of decisions connected with the management and control of mining operations and, from the educational point of view, enable the intricate problems of stability to be better.
If necessary, the operator should furnish a current 30 cfr 75. The intact properties of rock, rock mass condition, and. Installed ground support in mine development is compared to empirical estimates using the qsystem and associated support capacity calculations. Supported methods are used when production openi ngs stopes are not sufficiently stable. The stability of inter sections, therefore, is crucial to the wellbeing of a mine. To assess the stability, this paper presents a unified approach of observational, empirical, and analytical methods. In this manuscript, we present stability studies on two tunnels, a horseshoeshaped and an inverted archshaped tunnel, in a deep coal mine in china, performed using the 3dec distinct element code. Crown pillar stability assessment based on data collected from case studies of a copper mine csa mine, cobar and a leadzinc mine nbhc mine, was carried out in chapters five and six. Mininginduced stress change and related rockmass relaxation can drastically influence the stability of underground openings. The idea of the stress concentrations and their effects on the surroundings of the openings helps the design engineers to plan a suitable method of support system.
One of the most important aspects of underground hard rock mining is ventilation. Appendix d contains guidance for conducting pillar stability analyses. Review on rockburst theory and types of rock support in. Methods for computing the stability of mine openings. Yazici, geomechanics research center, sudbury, canada. Roof supports can only be understood in conjunction with the rock structure that they support. Hutchinson and diederichs9 recommend that an esr of not more than 3. Martin et al, 1999 stress path and instability around mine openings mineralized zone planned dilution unplanned dilution all all fw hw figure 4. For vertical shafts with circular section, it is equal approximately 2.
Supported methods require substantial amounts of artificial support to maintain stability in exploitation openings, as well as systematic ground control throughout the mine. A pdf version of this document can be downloaded from. Key laboratory of deep coal resource mining, ministry of education of. Reviews of research programs of the national institute for occupational safety and health. For the design of roof rock bolts, the span or width of the opening are considered in eq. Stress path and instability around mine openings rocscience. Tannant, university of alberta, edmonton, canada s.
To support these studies, some parameters are required. Use features like bookmarks, note taking and highlighting while reading mine openings. This paper relates to a ield study conducted at a large underground limestone mine in central pennsylvania. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The design of stable stope spans for shallow mining operations. Preliminary assessment of potential underground stability wedge. Due to this, it is important that proper underground stability assessments are performed throughout the life of mine as a part of an ongoing monitoring process.
Ventilation is the primary method of clearing hazardous gases and or dust which are created from drilling and blasting activity e. Mininginduced stress change and consequences of stress path. In this paper, a distinction is drawn between rock reinforcement or active support, where the supporting elements are an. Wipp established a comprehensive ground control program in order to manage the effects of creep on the stability of the mine openings. Thus, the objective of this study is to examine the effect of support types on the performance stability of underground tunnels that exist in hard.
Support of underground excavations in hard rock is the most. Csa mine, nsw australi, a was chosen as the first site for evaluation of the stability of crown pillars. Observational approach monitored the immediate roofs with geotechnical instruments. Guidelines for preparing mine closure plans in quebec foreword this document, guidelines for preparing mine closure plans in quebec hereinafter the guide, is a work tool available to the mining industry to facilitate the preparation of the land rehabilitation and reclamation plan. Esr excavation support ratio is a value that is assigned to an excavation in terms of the degree of security that is demanded of the installed support system to maintain the stability of the excavation. Support systems may be classified into two broad categories. Pdf rock support systems have become widely dominant components in underground hard rock mines. Rock support is the term widely used to describe the procedures and materials used to improve the stability and maintain the load bearing capacity of rock near to the boundaries of an underground excavation. The program includes monitoring and evaluation of underground conditions, timely initial installation of ground support, and renewal of ground support as necessary. Stability of deep underground openings through large fault.
This information is needed to design the support system andor estimate the amount of dilution. December 1997 page 5 foreword this department of industry and resources guideline has been issued to assist mine operators in the development of procedures relating to the application of sound. Figure 1 depicts a typical access strategy for platinum mine where the initial orebody is exploited by means of an incline or decline shaft system, and later accessed by vertical shafts. An imperative task for successful underground mining is to ensure the stability of underground structures. The mine openings may lead to the surface subsidence which can endanger the track safety. Primarily, the code required that full coverage support would be mandatory in mine openings greater than 3. Moreover, as this support system has been developed and used in another gold mine, pongkor underground gold mine in indonesia, the effect of this support system on the stability of roadways in pongkor mine and it characteristics are discussed by means of numerical analysis. Excavation geometry, distance and position between openings, and support design are the responsibilities of. Tunnel and underground mine openings in massive brittle rocks give rise to a. Pdf stability analysis of underground mining openings. May 06, 2011 conclusion for the analysis of stability of underground openings, the knowledge of stresses, strength and failure mechanism are important. It assumed that sufficient rock bolting would be installed to ensure the general structural stability of the excavation in which people may travel or work. They are used to maintain the stability of underground openings and reinforce disturbed rock masses after creating an excavation or starting mining activity. Data are graphically presented from 59 specially selected sites at 15 contributing mines.
Based on this, a system using rmi parameters in rock support design has been developed. Discontinuumequivalent continuum analysis of the stability. National research council and institute of medicine. Stability and support developments in geotechnical engineering series vol 40 josef aldorf on. Hutchinson and diederichs9 recommend that an esr of not more than 3 be used for temporary mine openings.
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