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Abstract Guanzhuang iron mine is one of a number of underground iron mines in the Eastern China，which is at depths of 500–1 000 m using the pillarless sublevel caving method. Stress measurements confirmed that，in Guanzhuang iron mine，the magnitude of the maximum horizontal stresses is typically 1.14 times greater than that of vertical stresses. The north mining area is at depths of 510–550 m，and movements are being measured 500 m or more far away from an active sublevel. Horizontal displacement figure shows one example of these measured movements and it can be seen that，in this case，lateral movements of about 50 mm were measured about 500 m away from a sublevel panel being extracted at a depth of about 510 m. There are no measurable vertical movements at this distance. Horizontal displacements due to underground mining are analysed by using the stochastic medium and numerical method. These lateral displacements have been termed as far field movements. It has become apparent that the far-field movements are due to redistribution of the high horizontal stress field in the sandstones and siltstones that overlie the Guanzhuang iron-seams.
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Received: 03 December 2008
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