Rock mass damage

Cai, M. et al. 2001. Quantification of rock mass damage in underground excavation from microseismic event monitoring. International Journal of Rock Mechanics and Mining Science, 1135-1145. 

REVIEW OF LITERATURE ON ROCK MASS DAMAGE DUE TO REPEATED BLASTING... 

It was required to measure the blast vibrations in the near-field as well as far-field zones with respect to blast site to assess the rock mass damage. Therefore a room of about 0.5m (lmxlmx0.5m) was excavated inside the sidewall for installation... 

Table 3. Extent of predicted rock mass damage into the tunnel wall...

Meyer, T., Drum, P. G. (1996). Fragmentation and Rock mass Damage Assessment - Sunburst Excavator and Drill and Blast. In Proceedings of the HARMS 1996 - Rock Mechanics Tools and Techniques (pp. 609-617). 

Paventi, M., Lizotte, Y., Scoble, M., Mohanty, B. (1996). Measuring rock mass damage in drifting. In Mohanty (Ed.), Rock Fragmentation by Blasting (pp. I3I-I38). 

Zhu. Z.. W Xu and A Zhang, Coupling model of seepage field and damaging field of fractured rock mass and its application, this volume, 2004. 

Zhang H, Zhou C and Yi L. 2000. Damaging osmotic tensor of rock mass under hydraulic coupling conditions. Geotech. Engng. World, 3(3), pp. 11-14. 

Zhu Z and Sun J. 1999. Analysis models for unsteady flow in fractured rock masses coupled with damaged field. J. of Hydrogeology Engineering Geology, Vol. 2, pp. 35-41. 

In Phase C (Rutqvist et al. 2003), the research teams performed calculations for the case where one or several water-bearing discrete fractures intersect the repository. As in Phase B, the temperature field shows nearly no difference between THM, TH, TM calculations and is very similar to the one in Phase B. The fracture(s) accelerates the resaturation of the buffer/backfill and prevents the desaturation of the rock mass. From a mechanical point of view, the fracture(s) constitutes a zone of weakness and results in a more extended zone of damage as compared to the homogeneous scenario. TH or THM calculations produce very similar pore pressure fields. With respect to the stresses in the buffer, the conclusions are similar to the homogeneous case, with a predominant effect of pore pressure on total stresses, compared to the thermal stresses. 

Conversely, the intensity of tensile stresses decreased and the rock mass does not risk any more a damage by rupture in traction. With regards to the model with the wide apart wells and galleries, behavior in compression is unchanged compared to the nominal case and the rupture zone in traction is a little more developed. 

The crust consists of upper, middle and lower floors. In the first one, where the thermodynamic interval is p < 0.2 GPa. T < 200° C, faults are narrow and the finite destruction is realized as vertical (I) or inclined (D) faults (Figure 1), whereas outside of them the rock mass remains in a slightly damaged state. 

COUPLED DAMAGE-SEEPAGE CONSTITUTIVE MODEL OF JOINTED ROCK MASSES AND ITS ENGINEERING APPLICATION... 

Along with the construction of a series of great hydropower stations, the problems of landslides caused by the rise of water level, and the stability of high slopes under the sharp rise of water pressure by rainfall are in critical needs in China. Consequently, the coupled problem of unsteady flow and damage of jointed rock mass are related to all above problems and is addressed in this paper. Some basic research works had been done by Yang (1995). The authors of this paper set up the coupled constitutive model of unsteady flow and damage, and the model was applied to analyze the stability of high slope of the permanent lock of TGP. 

DAMAGE EVOLUTION LAW OF THE JOINTED ROCK MASS 4.1 Damage evolution equation of Jointed rock mass under compression and shear... 

The damage evolution equation of rock masses are usually expressed as... 

Fractures at different stress states have different growth model and a damage evolution law is also established for this case based on the arguments described above. Because the more growth of fractures indicates the more degradation of the rock masses, the damage tensor can be expressed as the following... 

DAMAGE MODEL COUPLED WITH HYDRO-MECHANICAL BEHAVIOUR OF JOINTED ROCK MASS... 

Jointed rock mass can be regarded as equivalent continuum media if the distribution of fractures are in uniform style, a RVE (representative volume element) can be established, and the fracture flow controls the seepage of rock masses. A hydro-mechanical model of jointed rock mass coupled with damage is developed in this paper, based on the equivalent continuum assumption. From eqations (l) (i4), a FEM formulation can be established as below... 

Taking account into the damage evolution of jointed rock mass, the resilient displacement increases slightly during the excavation of the ship lock. Displacement apparently increases in the region of damage evolution and the maximum is in the middle of the left slope, the left of plumb wall and middle frusta. 

Cai M, Kaiser PK, Tasaka Y, Maejima T, Morioka H, Minami M. 2004. Generalized crack initiation and crack damage stress thresholds of brittle rock masses near underground excavations. Int. J. Rock Mech. Min. Sci, (41) 833-847. 

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