土木工程岩土工程裂隙岩体毕业论文中英文资料对照外文翻译文献综(6)

土木工程岩土工程裂隙岩体毕业论文中英文资料对照外文翻译文献综述

position of the center of rotation Ω.Since the kinematic approach of yield design states that a

necessary condition for the structure to be stable writes

it follows from Eqs. (5) and (6) that the best upper-bound estimate derived from this rst class of mechanism is obtained by minimization with respect to μ1 and μ2

which may be determined numerically.

Piecewise Rigid-Block Failure Mechanism [Fig. 4(b)]

The second class of failure mechanisms involves two translating blocks of homogenized material. It is de ned by ve angular parameters. In order to avoid any misinterpretation, it should be speci ed that the terminology of block does not refer here to the lumps of rock matrix in the initial structure, but merely means that, in the framework of the yield design kinematic approach, a wedge of homogenized jointed rock mass is given a (virtual) rigid-body motion.

The implementation of the upper-bound kinematic approach,making use of of this

second class of failure mechanism, leads to the following results.

where U represents the norm of the velocity of the lower block. Hence, the following upper-bound estimate for K+

:

Results and Comparison with Direct Calculation

The optimal bound has been computed numerically for the following set of parameters:

The result obtained from the homogenization approach can then be compared with that derived from a direct calculation, using the UDEC computer software (Hart et al. 1988). Since the latter can handle situations where the position of each individual joint is speci ed, a series of calculations has been performed varying the number n of regularly spaced joints, inclined at the same angleθ=10° with the horizontal, and intersecting the facing of the excavation, as sketched in Fig. 5. The

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