![]() ![]() In consequence, particularly because of the high cost of closure requirements, considerable interest is being focused on improving methods of assessing the stability of surface crown pillars. ![]() Establishing whether the remediation of specific surface hazards arising from mining activity is necessary in a given situation is not always straightforward. In many countries mines are now required to file closure plans and post bonds for decommissioning. Updated aids to application of the guidelines are presented for applying the mining Scaled Span concept for determining both mine opening and civil tunnel cover thicknesses of variable quality. This paper presents an updated methodology and a new chart developed through use of logistic regression techniques aimed at improving the ease of application of the Scaled Span method of Surface Crown Pillar dimensioning for assessing collapse risk. ![]() The fact that problems from collapses of near-surface workings have plagued mining operations for years led to the development nearly 20 years ago of the Scaled Span empirical design guidelines for crown pillar rock thickness dimensioning. The difficulties of predicting behaviour and of correctly dimensioning crowns is borne out by the fact that in recent years there have been a number of highly publicized near-surface mine working cave-ins and urban tunnel collapses, with breakthroughs to surface that have in several cases seriously damaged surface infrastructure. Calculations are made using finite element method using the software package ANSYS.Assessing collapse risk for any near surface mine opening or for a civil tunnel is challenging, while defining an appropriate minimum rock cover thickness that should be left above the crown is a particularly difficult design task. In the formulation of the problem of volume calculation is made eye fastening guys to span. Some fragments of the superstructure and the pylon designed as thin-walled space of local exposure to guys. The behavior of the span when wind impacts. They performed static calculations of cable-stayed span in linear and nonlinear formulations of the problem based on the sequence of mounting the stage of construction and operation. ![]() MIIT scientists carried out a large range of activities and checking calculations to evaluate the stress-strain state of the cable-stayed bridge span in the individual stages of installation and operation. Basic calculations and design of the bridge carried out “Giprotransmost”, but the design and construction of this unique artificial structures preceded research, which involved scientists Chairs “Bridges” and “Structural Mechanics”, Moscow State University of Railway Engineering (MIIT), and several other TsAGI organizations. ![]()
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January 2023
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