Rock Slopes Stability Analysis Of Strength Reduction Method Based On Modificationed Generalized Hoek-Brown Criterion

There are many slope stability analysis methods, among which the limit equilibrium method is traditionally used. In recent years, a new analysis method the strength reduction has sprung up. Combining with numerical calculating methods such as the finite element or finite difference, the strength reduction method can directly achieve the safety coefficient, the most dangerous slip surface and the stress distribution of the slope. Meanwhile, the slope instability process can be described. Currently, the strength reduction method is implemented against the Mohr-coulomb criterion which nevertheless has some limitations on the description of rock mass strength. Making up the deficiencies of the Mohr-coulomb criterion, the Hoek-Brown empirical strength criterion is consistent with the deformation as well as the failure characteristics of slope rock mass. Based on this, this thesis proposed a strength reduction method with an aim at improving the stability analysis for rock slopes against the Hoek-Brown criterion.First, based on the modification of Hoek-Brown strength criterion in previous studies, the uniaxial compressive strength weakening factor Dc and the rock mass integrity reduction factor De are introduced to establish the correction coefficient Km and Ks that take into account to which extent the rock mass has been disturbed. Thus a new modified Hoek-Brown formula has been obtained, which can better determine the parameters of rock mechanics between disturbed and undisturbed. The contrast of results of the rock mechanical parameters determine by model and measured data show that this modified formula is more reasonable.Secondly, in line with the modified Hoek-Brown strength criterion, a strength reduction method with an aim at improving the stability analysis for rock slopes is put forward. The results of an illustration example indicate that there is a very small difference between the safety coefficient obtained with the strength reduction method and that with the limit equilibrium method. That is to say, the feasibility of this strength reduction method has been verified.Finally, specifically for the anchor rod reinforcement rock slope, another strength reduction method for slope stability analysis under the effect of anchor rod reinforcement is proposed. The strength value reduced of the interface of the bolt and the rock mass is taken into consideration. The results of an illustration example reveal that as for the strength reduction method, it is more rational to take into account the strength value reduced of the interface than not to consider it.