Constitutive Theory And Experimental Study Of Special Rock In Metal Mine

As a natural geological material,rock is widely used in daily production and life.The study of rock mechanics theory is an important basis for the design and construction of underground engineering,tunnel engineering and civil architecture,and is also an important theoretical support for the development and application of rock mechanical properties.According to the experimental results,the titration model of rock is established,and the empirical criterion of power function type suitable for rock strength is put forward.It has good practical significance for similar brittle rocks.This paper concludes that:?1?The basic mechanical parameters of the standard rock samples were obtained by tensile,uniaxial and triaxial tests.The deformation curve and strength characteristics show that the density of rock samples affects their tensile strength.The strength,elastic modulus and Poisson's ratio of rock samples increase with the increase of confining pressure.The strength,peak strain and confining pressure of rock samples are proportional to the confining pressure of each stage.Through comparison,it is concluded that the shear parameters of rock samples are the most accurate at the peak value,the cohesion is 6.63MPa,the friction angle is 44.59°.The internal mineral composition of rock samples changes their strength and bearing capacity,and the uniaxial rock samples are tension-shear failure.?2?The expression of elastic and plastic constitutive relations in stress space is systematically introduced.The expression of plastic constitutive relations in stress space can be divided into yield surface and yield criterion,loading and unloading criterion and flow criterion.Based on the characteristics of the deformation of phyllite,the elastic-plastic-soft-structure model of phyllite is constructed,and the elastic-plastic-soft-structure model of phyllite is described in the strain space,which can be divided into yield surface and yield criterion,loading and unloading criterion and flow criterion.Based on the Mohr-Coulomb criterion and the experimental data,the constitutive equations of pre-peak plasticization and strain softening stage in strain space are derived.?3?According to the test data of phyllite,the?₁-?₃relationship curve is drawn,and the obtained data are fitted by several strength criteria applicable to rock materials.The results show that the prediction value of Mohr-Coulomb strength criterion is conservative,the prediction value of Hoek-Brown and generalized Hoek-Brown strength criterion is too high in high confining pressure zone,and the Yoshida empirical criterion can not predict the tensile stress of rock samples.On this basis,combined with the mechanical characteristics of phyllite,the empirical strength criterion of power function type suitable for brittle rock is put forward,and 5 groups of different lithologic rock samples in metal mine are fitted,and good results are obtained,it has certain engineering reference value.