Physical modelling of effect of joint density on deformation and failure of surrounding rocks

The producing and expanding mechanism of broken zone in surrounding rocks with different densities of intermittent joint in deep stratum was studied by physical modelling and digital photogrammetry for deformation measurement(DPDM) in geotechnical engineering.The failure and bulking deformation characteristics of surrounding rocks and their effect on the stability of a roadway were analyzed.It was shown that the density of joint greatly affected the bearing capacity of surrounding rocks.Intact rocks around a roadway could carry more elastic-deformation than jointed rock mass.Although jointed rock mass had the same bearing capacity as the intact rock,its stability and displacement were markedly different from the intact rocks.These properties of the intact rocks were better.With the same size of the broken zone,the more dense the joint was,the smaller the required stress would be,and vice versa.Under the same stress level,the more dense the joint was,the larger the bulking deformation,and the worse the stability of roadway would be.Therefore,the stability of surrounding rocks is controlled by joint density.