| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1996: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
The toppling failure and/or sliding failure often occur in jointed rock mass. The failure modes and their development failure process are greatly governed by the geometrical distribution of discontinuities. By assuming a rock mass as an assemblage of many polygonal rigid blocks, with picking up the relative size in comparison with the whole rock mass and the geometry of rock blocks, this research aims to assess the effect of shapes and sizes of blocks upon the energy loss while collapsing. The following 4 results were obtained by using the discontinuous deformation analysis (DDA) and the physical model test techniques: the base friction model, the centrifuge model and the tilt frame model. The first, by focusing the initial potential of each failure mode with respect to an single block, the shape of block have an obvious effect on not only the initial potentials but also the development post-failure motions. Some failure modes often reach to other different failure modes. The second, w
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ith respect to an assemblage of rock blocks, the local large dilation are induced in case of relatively large blocks by the stress concentration resulted from the interlocking, while relatively small blocks show larger modification performances like a continuum and the dilation are generated smaller but on the whole without concentrating in part because the tress are transferred fully and widely through the aspects of blocks without interlocking. The smaller the relative size, the total amount of discontinuities increases, so larger part of the energy is censured in many discontinuities as shear activity. The third, the dynamic failure extension process are calculated as the time-historical response against the sine-curve seismic wave by the DDA. While the seismic energy is consumed by the frictional action in case of the small void ratio, the seismic energy is consumed by the rigid body displacement which lead to the plastic form change in case of the large void ratio. The fourth, in order to monitor the rock activity, new method of removing the noise by weather change from measurement data as to the discontinuous rock slopes is proposed. Less
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