Interaction effects from earlier workings in seams above or below a seam presently being mined are a constant problem in the United Kingdom coalfields and are beginning to create difficulties in the United States. Based on a series of case studies, this paper attempts to define the major parameters governing the interaction mechanism. A broad relationship between the amount of damage caused by a rib edge or remnant pillar and the major parameters is developed from the case study results.
In the British coalfields, it is becoming increasingly uncommon to mine in virgin areas and it has been estimated that every working face will be affected by interaction effects from previous workings at least once during its life. (1) Because of the often severe strata control problems experienced, interaction constitutes a significant mining risk, and in recent years, has attracted the attention of a number of investigators. (2,3,4,5). This paper centers on the presentation of the results and conclusions of a number of case studies of interaction situations carried out mainly in the Northeast Coalfields. Emphasis is given to discussion of those factors identifiable as being of importance to the interaction effect rather than detailed descriptions of each investigation site. It is considered that it may be possible to achieve substantial improvements to the safety and profitability of mine workings by a better understanding of the interaction problem.
King (1 ) has classified interaction as originating from three main causes:
(1) Stress fields due to old or current workings--static interactions.
(2) Active strata displacement in other workings due to current workings-- dynamic interaction.
(3) "Triggered" interaction due to changes produced by current workings upon old workings.
Space considerations necessitate concentration on static interaction effects in this paper.
