The negative effect of a torsion dissipative structure on the stability and bearing capacity of the yield frame support

Abstract

Yieldable frame support (YFS) is the most important primary component of a tunnel or underground roadway propping in a consequent set of multistage support technology, which is employed in the squeezing rock. This research aimed to enhance the efficiency of combined support using the synergetic effect of connecting YFS to the rock bolts/cables (YFSB). Employing the methods of actual measurements and survey, computer simulation, and underground testing of YFS, we investigated conditions that provoke a spontaneous torsion of the YFS profile, which caused YFS stability failure, loss of the bearing capacity and integrity. We revealed a longitudinal twist or torsion of the YFS profile as a new mode of YFS stability failure and demonstrated that the torsion is a consequence of a scale effect. Based on the thermodynamics of irreversible processes, we proved that this torsion is a form of dangerous dissipative structure that minimizes entropy production. We investigated the torsion parameters and developed a new joint between YFS and rock bolt, which is a key element of a novel lean technology that effectively prevents the YFS profile torsion. The joint and its optimal parameters were successfully tested in an underground condition that provided YFSB stability, increased its average resistance, conserved total bearing capacity, and integrity.