Weakness, plane

It has been calculated that the strength of a weak plane in the transverse (vertical) direction must be less than one-fifth of the tensile breaking stress in order to induce a crack to turn sideways [24]. Lake et al. [25] considered the energy release rate Gs available for further growth of a sideways crack that is already long, and concluded that Gs is a rather small fraction of the value Gp for forward growth ... 

The schistocity contains sericite and acts as a dominant low fnction angle weakness plane in the rock mass. These weakness planes form platy blocks up to 50 mm in thickness. The lenticular shaped massive pyrite orebody, with thickness up to 20 m has lateral and vertical dimensions of 300 m and 1500 m respectively. 

Burden to spacing ratio from 0.8 to 1.2 is appropriate for wall-control blasting. Weak planes act as free faces and its position determine amount of back break. 

Jeon S., Kim X, Seo Y. 2004. Effect of a fault and weak plane on the stability of a tunnel in rock—a scaled model test and numerical analysis. International Journal of Rock Mechanics Mining Sciences. 41(3) l-6. 

Tziallas, G. 2010. Estimation of strength and deformabil-ity characteristics of composite rocks. MSc Thesis, Geotecniced Engineering Department, NTUA. Vutukuri, V.S., Hossaini, S.M.F. Foroughi, M.H. 1995. A study of the effect of roughness and inclination of weakness planes on the strength properties of rock and coal. Proc. of Mechanics of Jointed and Faulted Rock 151 155 Balkema. 

The only exception to note is that the strength is reduced to 50% if the clay is fissured because of the extra weakness planes offered by discontinuities. 

Bruns et al. pioneered self-reporting materials based on the mechanical perturbation of proteins within polymeric matrices/ " The protein cage thermosome (THS), a chaperonin from the archaea Thermoplasma acid-ophilum, is composed of sixteen protein subunits that form two hemispheres with the ability to enclose macromolecular guests (Figure 11.13)/ THS is approx. 16 nm in diameter. The hemispheres of chaperonins are connected through a mechanically weak plane, so that the two halves of these protein cages can be separated from each other by mechanical forces, as demonstrated in AFM experiments.THS was turned into a sensor for mechanical deformation by covalently linking two proteins, enhanced cyan fluorescent protein (eCFP) and enhanced yellow fluorescent protein (eYFP), into the... 

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