1、英文原文The influence of roadway backfill on the coal pillar strength by numerical investigationHongwei Wang a, Brett A. Poulsen b, Baotang Shen b,n, Sheng Xue b, Yaodong Jiang a(a China University of Mining and Technology, Beijing 100083, China ; b CSIRO Division of Earth Science and Resource Engineeri
2、ng, PO Box 883, Kenmore, QLD 4069, Australia)abstract：Stability of coal pillars and immediate rock mass is of importance in the bord and pillar extraction method underlying critical surface infrastructure. This paper describes the influence of roadway backfill on the coal pillar stability. Based on
3、over 120 numerical models of various pillar height and backfill percentage, it is indicated that the pillar strength will increase with increasing roadway backfill, while the increase in pillar strength is greater for tall pillars than squat pillars for both cohesive and non-cohesive backfill. Model
4、ling suggests that cohesive backfill is more effective in increasing both peak and post-peak pillar strength than non-cohesive backfill. It is also observed that the post-peak response will change from softening to hardening at a certain percentage of either cohesive or non-cohesive backfill.Crown C
5、opyright & 2010 Published by Elsevier Ltd. All rights reserved.Keywords:Roadway; backfillPillar;strengthPost-peak;responseSofteningHardening1. IntroductionIn the bord and pillar mining method, pillars are left to controlmine stability and surface subsidence, and hence to prevent damage to surface or
6、 near surface features, e.g., buildings, railways, highways, rivers, pipelines, etc. Improvement of pillar stability can be achieved by leaving large pillars or using secondary support methods such as bolts, mesh and roadway backfill. Roadway backfill as a support method may be achieved through bore
7、holes from the surface, eliminating the need for people to work underground and allowing pillar strength improvement post-mine closure.Considerable research in the stability of pillars has been carried out particularly for coal mines. Several aspects of this research are discussed here. The coal pil
8、lar design must take into account the mechanical and physical properties of the coal. In the area where extraction of coal is mainly done by the bord and pillar mining method, empirical data on the relationship between the strength of a coal pillar and the size of the pillar is essential for the des
9、ign of coal pillars. For this purpose, Bieniawski 1 in 1967 established an empirical relationship between in situstrength of coal and the size of the pillar. Furthermore, in a comprehensive study with the objective of establishing a framework for the in situ strength and deformation properties of co
10、al pillars at a range of width-to-height ratios, Medhurst and Brown 2 in 1998 investigated the effects of size on coal strengthby a series of triaxial compression tests to provide engineers witha practical and systematic method for estimating the mechanicalproperties of a coal seam.The coal pillar s
11、trength is fundamental to pillar design: Salamon and Munro 3,4 proposed an empirical approach based on pillar width and height for pillar strength calculation in South African coal mines that has found wide international application. In the 1990s a database of Australian coal pillars 5,6 wasanalysed
12、 both in isolation and combination with the South African database used by Salamon and Munro and a similar empirical strength formula was proposed. To investigate the complete load deformation behaviour of coal pillars, a set of rectangular and square coal pillars was tested in situ by Wagner 7,8 in
13、 1974 and 1980. The research highlights the distribution of stress in a coal pillar and the importance of the pillar core of yielded coal which may remain effective at peak strength.In a mine panel consisted of many pillars and roadways, the stability is a function of the strength of each coal pilla
14、r and the interaction between pillars. In particular, the residual strength will influence the load transfer between pillars if one of them is to fail. Consequently, pre- and post-failure mechanism of a coal pillar is essential to understand the load transfer between pillars in the mine panel. Exten
15、sive experimental test and numerical analyses have been carried out to study the post-peak strength of stress-strain response of a coal pillar 7,9-13.The stability of pillars for a period longer than mine life is of great importance to prevent damage of surface features into the failure. Deformation
16、 and strength change of a coal pillar during and after mining were analysed to establish long-term stability ofcoal pillars. An integrated design method was proposed by Bieniawski in 1994 14 to provide researchers with means to improve the stability of a coal pillar as well as to promote the gradual reduction rate of surface subsidence. Some important work has been done by Salamon and Ozbay 15 to investigate the extent and rate of scal
