1、翻译部分英文原文A Method for The Design of Longwall Gateroad Roof SupportW.LawrenceGeowork Engineering, Emerald, QLD, AustraliaAbstract:A longwall gateroad roof support design method for roadway development and panel extraction is demonstrated. It is a hybrid numerical and empirical method called gateroad r
2、oof support model(GRSM), where specification of roof support comes from charts or equations. GRSM defines suggested roof support densities by linking a rock-mass classification with an index of mining-induced stress, using a large empirical database of Bowen Basin mining experience. Inherent in the
3、development of GRSM is a rock-mass classification scheme applicable to coal measure strata. Coal mine roof rating(CMRR) is an established and robust coal industry standard, while the geological strength index(GSI) may also be used to determine rock-mass geomechanical properties. An elastic three-dim
4、ensional numerical model was established to calculate an index of mining induced stress, for both roadway development and longwall retreat.Equations to calculate stress index derived from the numerical modeling have been developed. An industry standed method of quantifying roof support is adopted as
5、 a base template (GRSUP). The statistical analyses indicated that an improved quantification of installed support can be gained by simple modifications to the standard formulation of GRSUP. The position of the mathematically determined stable/failed boundary in the design charts can be changed depen
6、ding on design criteria and specified risk.Key words:Coal mine;Roof control;Support;Design.1 IntroductionLongwall gateroad strata stability is essential to ensure uninterrupted production. In Central Queenslands Bowen Basin, immediate gateroad roof lithology varies from coal to weak interlaminated m
7、aterial, to strong almost massive sandstone, with localised areas of weak fault affected strata. It is usual for roof conditions within any one mine to vary signicantly. Typically, longwall mines in the Bowen Basin have specied gateroad roof support based on past practice. Modications to gateroad su
8、pport are generally reactive, due to encountered difcult strata conditions, and less proactive. Current gateroad support design approaches have limitations, which have restricted their applicability and adoption as mine site design tools.2 Current Roof Support Design Methods for Longwall GateroadsEn
9、gineers and mathematicians do not have the current capability to fully dene rock-mass geomechanical properties and their mathematical representation. Elasticplastic numerical modelling is a useful tool if used appropriately. It is not exclusively correct or unique, or always superior to other availa
10、ble and accepted design techniques. These aspects have been recognised during recent collaborative Australian Coal Association Research Program research on longwall microseismics, where it was considered that current 3D numerical models lack sufcient validated constitutive relationships, and are for
11、ced to make compromises when dealing with complex rock-mass behaviour.Simplied elastic numerical methods have merit and are certainly applicable for more massive sedimentary rock-masses. An assessment of their applicability to weaker, laminated clastic rock-masses is required. Hybrid numerical and e
12、mpirical methods have been developed for the geotechnical design of undercut and production level drifts of block caving mines.3 Geotechnical Roof Classication of Longwall GateroadsTwo classication schemes were considered appropriate. Firstly, the coal mine roof rating(CMRR), which is an established
13、 coal industry standard. Secondly, the Geological Strength Index, GSI with strength parameters included. A recent publication has contended that GSI estimates of rock-mass strength should not be used for coal mine roof problems, where the geometrical scale of the problem is similar to discontinuity
14、spacing. A distinction needs to be made between the GSI classication and the related HoekBrown failure criterion. This scale effect and situations where the failure criterion should not be used have been discussed. However, this does not mean that a classication of the rock-mass cannot be made. Inde
15、ed, this scale issue is a problem inherent in any rock-mass classication scheme, not just GSI, and for any failure criterion. For example, some mines appropriately use unconned compressive strength (UCS) as an index or failure criterion, but UCS is also scale dependent and has the same limitations.W
16、ithin the support design methodology, the rock-mass classification schemes will link mining-induced stresses (or stress index) and required installed roof support. Therefore, the classifications should be independent of environmental and geometrical factors, such as mining induced stresses and excavation orientation and size. A rock-mass classification scheme must also provide rock-mass geomechanical properties to enable the calcu
