An improved method to assess the required strength of cemented backfill in underground stopes with an open face

Abstract Backfill is increasingly used in underground mines to reduce the surface impact from the wastes produced by the mining operations. But the main objectives of backfilling are to improve ground stability and reduce ore dilution. To this end, the backfill in a stope must possess a minimum strength to remain self-standing during mining of an adjacent stope. This required strength is often estimated using a solution proposed by Mitchell and co-workers, which was based on a limit equilibrium analysis of a wedge exposed by the open face. In this paper, three dimensional numerical simulations have been performed to assess the behavior of the wedge model. A new limit equilibrium solution is proposed, based on the backfill displacements obtained from the simulations. Comparisons are made between the proposed solution and experimental and numerical modeling results. Compared with the previous solution, a better agreement is obtained between the new solution and experimental results for the required cohesion and factor of safety. For large scale (field) conditions, the results also show that the required strength obtained from the proposed solution corresponds quite well to the simulated backfill response.

[1]  Li Li,et al.  A new concept of backfill design—Application of wick drains in backfilled stopes , 2013 .

[2]  Steve Zou,et al.  Optimizing backfill design for ground support and cost saving , 2006 .

[3]  Li Li,et al.  Formulation of a three dimensional analytical solution to evaluate stresses in backfilled vertical narrow openings , 2005 .

[4]  Michel Aubertin,et al.  An analytical solution for the nonlinear distribution of effective and total stresses in vertical backfilled stopes , 2010 .

[5]  Michel Aubertin,et al.  An improved analytical solution to estimate the stress state in subvertical backfilled stopes , 2008 .

[6]  Qiang Zhang,et al.  Backfilling technology and strata behaviors in fully mechanized coal mining working face , 2012 .

[7]  B. Muhunthan,et al.  Effect of cement treatment on geotechnical properties of some Washington State soils , 2009 .

[8]  Michel Aubertin,et al.  A modified solution to assess the required strength of exposed backfill in mine stopes , 2012 .

[9]  Richard J. Bathurst,et al.  Closure to “Predicted Loads in Steel Reinforced Soil Walls Using the AASHTO Simplified Method” by Richard J. Bathurst, Axel Nernheim, and Tony M. Allen , 2011 .

[10]  Michel Aubertin,et al.  Numerical Investigation of the Stress State in Inclined Backfilled Stopes , 2009 .

[11]  Hans Vaziri,et al.  Strength of Weakly Cemented Sands from Drained Multistage Triaxial Tests , 2011 .

[12]  Jian Li,et al.  An investigation of surface deformation after fully mechanized, solid back fill mining , 2012 .

[13]  Hans Vaziri,et al.  Use of A¯=0 as a Failure Criterion for Weakly Cemented Soils , 2011 .

[14]  Robert J. Mitchell,et al.  Model studies on cemented tailings used in mine backfill , 1982 .

[15]  Othman Nasir,et al.  Mechanical Behaviour of the Interface Between Cemented Tailings Backfill and Retaining Structures Under Shear Loads , 2010 .

[16]  David F. McCarthy,et al.  Essentials of Soil Mechanics and Foundations: Basic Geotechnics , 1982 .

[17]  Richard J. Bathurst,et al.  Predicted Loads in Steel Reinforced Soil Walls Using the AASHTO Simplified Method , 2009 .

[18]  Xie-xing Miao,et al.  Waste-filling in fully-mechanized coal mining and its application , 2008 .

[19]  Michel Aubertin,et al.  Integrated mine tailings management by combining environmental desulphurization and cemented paste backfill: Application to mine Doyon, Quebec, Canada , 2008 .

[20]  Michel Aubertin,et al.  A Three-Dimensional Analysis of the Total and Effective Stresses in Submerged Backfilled Stopes , 2009 .

[21]  Joseph E. Bowles,et al.  Foundation analysis and design , 1968 .