Experimental Study On Dilatation Deformation And Strength Character Of Diabase

Under uniaxial compression and low confining pressure,rock mass expansion(dilatation)is a special deformation rule of rock material.The deformation of the surrounding rock fracture zone is mainly caused by the deformation of the fracture.Therefore,the study of the mechanical properties after rock fracture,such as shear deformation and deformation,it is of great theoretical and practical value to study the shear deformation mechanism of surrounding rock fracture zone.At the same time,the surrounding rock fracture zone is formed by cyclic loading and unloading.In order to better simulate the actual force process of rock,the rock is subjected to the peak cycle and unloaded.It can also help people better understand the stress and strain characteristics of rocks.Through the conventional triaxial compression test and residual strength section cyclic loading and unloading test,the dilatation characteristics,deformation mechanism and strength characteristics of dolerite were studied by using TAW-2000 microcomputer control rock triaxial test system.The main conclusions are as follows:(1)The deformation characteristics of dolerite.In the triaxial compression stage,the end point of the pore crack compaction and the initial point of expansion occur at the same time.The yield limit occurs at the same time as the starting point of the shear bulge.In this way,the corresponding relationship between the dilatation deformation and stress-strain curve of the diabase is constructed.The larger the confining pressure is,the smaller the volume strain is.Therefore,it is known that confining pressure has a inhibitory effect on the shear of rock.The axial strain increases with the increase of confining pressure,which reflects the delayed effect of confining pressure on the occurrence of shear swelling.In residual strength long loops and unloading,loading process,with the increase of axial strain also displayed and volume strain of rock before the peak compression similar form of change,volume strain increases first and then the volume increase with the decrease of the first,every load experienced compaction is first,then the process of dilatancy.In the process of post-peak cyclic loading and unloading,the unloading comparison of the load will have a great influence on the volume strain of the specimen.(2)Intensity characteristics of ophiolite.After the damage,the rock shows the sensitivity of the change of confining pressure after the peak of the rock,indicating that the residual strength can be greatly increased by applying the smaller support resistance after the surrounding rock failure.The difference of residual strength difference between different confining pressures and different unloading ratios is different,but the variation of residual strength difference and cycle times can be obtained by using uniform formula.(3)Analysis of ophiolite dilatation.For underground engineering,from the excavation of freedom to the deep extension of the surrounding rock,the dilatation angle is not a constant,but a constant evolution value.In the process of rock sample loading,as the deformation increases,the dilatation angle of the rock sample increases sharply.After the rock sample enters the peak strength,the increase rate of the expansion angle decreases.With the increase of confining pressure,the curve tends to be flat,that is,the change of the dilatation angle increases with the increase of confining pressure.Peak dilatancy angle and residual dilatancy angle decreases with increasing confining pressure,this is due to the confining pressure,the greater the shear effect,the more the easier caused bulge tip is cut,make internal fracture rock moving up the smaller displacement component of laws.Residual strength for loops and unloading phase with the increase of cycling times,diabase dilatancy angle will be lower,show that with the increase of cycling times,rock dilatancy deformation continues to develop,but increasingly attenuation dilatancy effect,is due to the increased with the increase of cycling times,rock crushing,dilatancy slip is becoming more and more is not obvious.Above all,the paper through the triaxial compression test and residual strength long loops and unloading test,from the perspectives of qualitative and quantitative,even dilatancy effect and its failure mechanism,it is concluded that the innovative research results,the theoretical research,engineering design and actual construction has a certain theoretical significance and practical value.