Study on anisotropic mechanical properties and fracture characteristics of slowly dipping stratiform rock mass
In an effort to investigate the effect of structural characteristics on the anisotropic mechanical prop-erties and fracture evolution characteristics of gently dipping layered rock masses,a multifaceted experimental study was executed.This experiment factored in different structural characteristics parameters such as distinct structural plane spacings,strengths,inclination angles,and model size effects pertaining to gently inclined lay-ered sand and mudstone.A numerical mechanical model of gently dipping layered rock mass was devised grounded on the particle flow method.The parameters of layered sand and mudstone were calibrated through laboratory experiments,with the efficacy of the proposed model verified subsequently.This research precipi-tated an innovative investigation into the crack development rate of layered rock mass structural planes via par-ticle flow numerical mechanics experiments.The findings unveiled the strength anisotropy and fracture evolu-tion characteristics inherent in gently dipping layered sandstone and mudstone.Consequently,relationships were delineated between its mechanical properties and the triad of structural characteristics,i.e.,structural plane spacings,strengths,and inclination angles.The salient findings from this research can be synthesized as follows:(1)The discrete element mechanical model established by leveraging the flat joint model(FJM)and smooth joint model(SJM)is effective in characterizing the strength anisotropy mechanical features and frac-ture evolution process of gently dipping layered rock masses.(2)The tangent modulus and strength of gently inclined layered rock mass amplify with increasing interlayer spacing and interlayer strength but diminish with a rise of structural plane inclination angles.The fracture characteristics are increasingly influenced by the struc-tural plane,leading to the computation of the critical angle for shear failure of the structural plane at 24.5°,in accordance with the single group structural plane theory.(3)The development velocity of structural plane cracks lessens with expanding spacing between structural planes and declines of structural plane inclination angles.Notably,changes in the strength of structural planes don't yield a significant impact.Crucially,these re-search findings pave the way for more comprehensive studies on the mechanical behavior and surrounding rock stability of gently inclined rock tunnels.
Gently layered rockAnisotropyGranule flowRupture characteristicsFlat joint modelSmooth joint model
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