Abstract
Before achieving yielding support with artificial pillars, it is significant to evaluate their active support and passive bearing performances on the stope roof. This paper focuses on three aspects of research using 3DEC numerical simulation, which are support patterns of artificial pillars, magnitude of support stresses, and the magnitude of prestresses of the load‐increasing yielding support pattern. Simulation results show that the superior sequence of supporting effect is load‐increasing yielding support, load‐shedding yielding support, and constant and nonyielding support under the same initial support stress. When the magnitude of support stress or the magnitude of prestress is larger with load‐increasing yielding support, the supporting effect is superior and the load‐increasing yielding support with a lower magnitude of support stress is superior to some other support patterns with higher magnitude of support stresses. The active support can improve the support effect compared with no prestress, and under the same final support stress, the support effect is superior when the roof stress releases more in the early supporting stage regardless of the prestress.
Highlights
Pillar damage can be divided into structural failure and functional destruction
When the bearing stress on the pillar reaches its peak strength, the pillar begins to shed and yield, and this type of structural failure represents the decrease in the bearing capacity of the pillar, which results in the loss of the support capacity and the final functional destruction [1]
A yielding pillar is difficult to form because it must meet two basic characteristics; on the one hand, it must ensure that the pillar gradually yields, but not suddenly damaged, and on the other hand, the pillar needs to have enough residual strength to support the load of rock mass below the pressure arch [5, 8]. roughout the previous studies on the yielding pillars, which mainly focused on the failure process of natural pillars of different sizes by field observation and numerical simulation [9,10,11,12], since the stiffness of natural pillars is generally fixed, the pillar size becomes the only influencing factor to form yielding condition
Summary
When the bearing stress on the pillar reaches its peak strength, the pillar begins to shed and yield, and this type of structural failure represents the decrease in the bearing capacity of the pillar, which results in the loss of the support capacity and the final functional destruction [1]. Between the beginning of yield and complete failure, the natural pillar is known as a “yielding pillar,” which is first proposed for the room and pillar mining method to form a stress release region on the stope roof to reduce the load on the natural pillar [2]. Yielding pillars have been proposed and developed for many years in coal mines [3, 4] and hard rock mines [5, 6], which were proven to be economical and safe [7] because the size of pillars and the roof stress can be reduced and released.
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