Experimental modelling on rockburst in deep hard rock circular tunnels#br#
GONG Fengqiang1，2，LUO Yong1，SI Xuefeng1，LI Xibing1，2
(1. School of Resources and Safety Engineering，Central South University，Changsha，Hunan 410083，China；2. Institute of Mechanics for Engineering Materials，Advanced Research Center，Central South University，Changsha，Hunan 410083，China)
Abstract：In order to understand the mechanism of slab buckling rockburst in deep tunnels in hard-rock，a large scale true-triaxial rock test system was used in the modelling experiments on the red sandstone samples(100 mm× 100 mm×100 mm) with a prefabricated hole. The minimum principal stress was set in the horizontal direction perpendicular to the axial direction of the tunnel，the maximum principal stress was set in the vertical direction perpendicular to the axial direction of the tunnel and the initial stress state was achieved in three directions. The loading in the vertical direction perpendicular to the axial direction of the tunnel was increased until the tunnel wall began to damage, while the initial stresses in the other two directions were maintained the same. The stepwise loading was executed until the rockburst occurred while the specimen as a whole was not completely damaged. The whole process of rockburst occurred in tunnel wall during the test was monitored and recorded in real time with a miniature camera installed. The entire process of slab buckling rockburst of the deep hard rock tunnel is thus reproduced. The results show that the slab buckling rockburst can be divided into four periods，i.e.，the quiet period，the fine particle ejection and peeling period，the slab buckling damage and the strong damage. The slab buckling rockburst may occur lagging behind the stress，has a time effect，and is obviously affected by the loading rate. The failure depth of slab buckling rockburst reaches the stable state of higher static stress level. The formation of the V-shaped notch has a stress insensitive period. The optimization of geometric parameters of the tunnel cross-section plays a role in the size effect of the structural strength，which has a certain inhibitory effect on the slab buckling rockburst.
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GONG Fengqiang1，2，LUO Yong1，SI Xuefeng1，LI Xibing1，2. Experimental modelling on rockburst in deep hard rock circular tunnels#br#. , 2017, 36(7): 1634-1648.
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2017, Vol. 36 
