|
Abstract Because of surrounding rock deformation fracture in deep-buried and high geostress conditions，the project problem is very prominent at Jinping II hydropower station underground engineering. The bedded marble which is collected from the Jinping II hydropower station auxiliary traffic tunnel is used for three-point bending experiment on different loading directions with the scanning electron microscope(SEM) high temperature fatigue testing system. The relation between different bedding directions marble?s failure mechanism and strength parameter is analyzed through comparison with homogeneous marble；then the infection to fracture mechanism of surrounding rock by the different loading directions to bedded marble is researched. The results show that the banded structure feature between dolomite mineral particles and calcite mineral particles leads to bedded features of marble；loading direction is the final factor to the fracture mechanism，the failure mechanism of homogeneous marble is that the crack propagation propagate between dolomite mineral particles，when loading direction plumb the bedding；the failure mechanism is coupling fracture with that the cracks penetrate calcite mineral particles and propagate between dolomite mineral particles；and when loading direction parallels to the bedding，the failure mechanism mainly is that the cracks propagate between mineral particles. The difference of strength parameter is disciplinary on macroscopy because of different fracture mechanisms，such as the peak load of homogeneous marble and parallel bedding specimen is 0.58 times and 0.44 times than vertical bedding specimen?s；and the breaking energy is 0.42 times and 0.29 times. The three groups of marble fracture surface as the fracture mechanism? expression on macroscopy has self-similar fractal features.
|
|
Received: 08 April 2011
|
|
|
|
2012, Vol. 31 
