Experimental Study On Mechanical Properties Of Diabase Fracture-grouting Mass

The rock mass in nature is affected by long-term complex geological tectonic stress.The rock mass develops discontinuous structural planes or broken rock masses with different degrees of fissures,joints and faults,which significantly reduces the strength and stability of the surrounding rock.And during the excavation process,the rock mass during tunnel or slope excavation is prone to rupture and instability,the collapse of the face and the delayed rupture.Therefore,in order to accurately analyze the weakening effect of fracture geometry on rock mass mechanies properties,this paper takes diabase and its fracture-grouting consolidation binary media rock mass as the research object,aiming at three kinds of fracture geometric variables,the dip angle of the fracture,the degree of fracture penetration and the number of cracks respectively.According to the deficiencies of the current two-phase "rock-slurry,medium constitutive relationship,the uniaxial and conventional triaxial compression tests of diabase and binary media and the indoor grouting test of fractured rock samples have been carried out,in order to research the mechanical properties of diabase and binary media,the sensitivity analysis of fracture geometry and the constitutive equation of compressive deformation of diabase fracture-grouting mass in one-dimensional conditions.The main conclusions are as follows:(1)The peak strength,residual strength,peak strain,residual strain,elastic modulus,modulus of deformation and Poisson's ratio of diabase show a tendency to increase with the increase of confining pressure.Among them:peak strength,residual strength,peak strain and residual strain all show significant linear growth relationship,which can be fitted by one-time function;elastic modulus,deformation modulus and Poisson's ratio all show obvious nonlinear growth relationship,which can be fitted in the form of a power function,and tends to a stable value as the confining pressure increases;(2)According to the characteristics of standard fractured rock samples,the simple grouting mould of cracked rock sample is innovatively designed,which is characterized by simple and light,convenient processing,flexible operation and easy control,and good grouting effect;(3)The elastic modulus,deformation modulus and peak strength of diabase fracture-grouting mass decreased significantly with the increase of the fracture penetration(0%?100%),the fracture inclination angle(30°?45°)and the number of cracks(1-3).Among them:when the angle of inclination of the fracture is 30° and 45°,the elastic modulus and deformation modulus decrease linearly with the increase of the fracture penetration degree,and while the inclination angle of the fracture is 60°,the elastic modulus and deformation modulus show the law decreases exponentially with the increase of the degree of fracture penetration;The peak strength under the full penetration condition accords with the exponential reduction law,while the peak strength under the semi-through condition accords with the linear reduction law;With the increase of the number of cracks,the elastic modulus and the deformation modulus are in accordance with the law of decreasing the power function,and the peak strength is in accordance with the linear decreasing law;(4)The stress brittle drop coefficient is calculated by the plastic potential theory,and the segment-form equation of stress-strain relationship satisfying the complete rock mass is established.The fitting effect is better with the experimental data.At the same time,it is found that the stress drop coefficient has a significant positive linear correlation with the confining pressure.The smaller the value,the stronger the brittleness;Through the force analysis,geometric relationship and related fracture surface compression closure formula,the shear-slip and compression-closed constitutive equations of diabase fracture-grouting mass are established,and the inadequacies are analyzed;Based on the principle of mechanical model of series deformation element,the actual deformation law of diabase fracture-grouting mass in the experiment and the results of related scholars,a constitutive equation suitable for diabase fracture-grouting mass under one dimensional full penetration condition is established.