Experimental Study On Creep Characteristics Of Deep Surrounding-Rock And Numerical Simulation

Rheological behavior is one of the most important mechanical character of the rock, andits major research method is to carry out a rheological mechanical test. As with the depth’sincensement, during the large underground cavern and tunnel’s construction and its laterperformance, it emerges such problems as safety and stability. Further more, the large-scalerock program demands a further study of rock rheological mechanics. So it is significant tomake a research of rheological mechanical property of the rock mass （especially refers toweak surrounding rocks in the deep part） theoretically and practically under uniaxial stressand three-dimensional stress. This paper is based on State Natural Sciences Foundationproject （No.50874043） about the creep damage character and its application study in the deepsurrounding rock. The author made tests combined with numerical simulation analysisthrough the project in Niu Masi colliery at Shaodong, Hunan Province. With homotaxial andtriaxial compression deformation test and creep deformation test, the author has discussed theinstantaneous mechanical strength and deformation character and rheological mechanicalcharacter. This paper is aiming at the study of the rheological mechanical character ofsiltstone within different stress level and conditions, and builds its corresponding homotaxialand triaxial rheological constitutive model, and develops a user-defined constitutive modelunder the condition of VC++and learns to invoke user-defined constitutive model withFLAC^3D. Furthermore, a numerical simulation study of creep test has been made with thesame conditions of indoor creep test, and a sensitivity analysis of creep character has beenmade with different parameters.The major tasks are as follows:（1） With the research result of homotaxial and triaxial instantaneous mechanicalcharacter concluded from RMT-150C servo test machine. From the aspect of stress-straincurve’s character, strength and deformation index and damage pattern, the paper analysesinstantaneous mechanical character of siltstone and its change regular under the condition ofhomotaxial and triaxial with diverse confining pressure, which also discussed theinstantaneous damage mechanism of siltstone when in different stress state.（2） The author has made a homotaxial and triaxial rheological test of siltstone by usingRYL-600rock triaxial rheological testing machine, which find out a rule that the axial strainwill change as time’s change in different stress levels and confining pressures, which alsoanalyses the equivalent stress stress-strain curve feature. Through a viscoelastic-plastic separation of the test data, this paper also makes a further study of viscoelastic-plastic featureof rock rheological behavior and the change rule of axial strain and axial rheological rate witha rock creep damage load, what’s more, it makes a comparative analysis of axial and lateralcreep change rule, all of which afford a experimental basis for parameter’s variation when dorheological numerical analysis and help to find out the rule of homotaxial and triaxialrheological character.（3） Based on the research result of uniaxial rheological test of siltstone, by means ofimproving the ideal plasterer, further made it cascade with the generalized kelvin body, it gota new sticky elastic-plastic rheological model （mcvisc model） with six component which cancomprehensively reflect the rock ’s transient elasticity, transient plasticity, sticky elasticity andsticky plasticity; Based on the research result of triaxial rheological test of siltstone, on thefoundation of west master model, by means of cascading a kelvin body, it got a stickyelastic-plastic rheological model （mcvisc2model） with seven component which cancomprehensively reflect the rock ’s transient elasticity, sticky elasticity and sticky plasticity.Based on the curve of uniaxial and tri-axial rheological test, making use of the mathematicalsoftware Origin8.0’s strong nonlinear fitting function to the user-define fitting function, doingparametric identification for the established uniaxial and triaxial rheological constitutivemodels.（4） Based on the established uniaxial and triaxial rheological constitutive models, madeits three-dimensional form’s constitutive relation deduced the finite difference form, under theenvironment of VC++, based on the embedded existing cvisc model of FLAC^3D, realized theprocedure development of the user-define constitutive models to the uniaxial and the triaxialrheological models and compiled into dynamic-link library file mcvisc.dll and mcvisc2.dllseparately. Making use of the embedded constitutive model of FLAC^3Dto verify model’sdegradation form, in order to demonstrate the validity and adaptability of the modeldevelopment. Based on these, this paper made a brief introduction for the proceduraldevelopment process and the key problems in the process.（5） Used the user-define constitutive model （mcvisc model and mcvisc2model） in thesoftware FLAC^3Dseparately, developed the simulation study of the uniaxial and triaxialnumerical rheological test in the same condition with indoor rheological test, by comparingthe numerical result and rheological test result, verified the validity and adaptability of theuser-define model. Based on the numerical test result, further exploring the axial and lateralrheological change rule and comparatively analyzing its sensitive difference for therheological change, at the same time,comparatively analyzing the rheological change rule which is lateral to different positions for the test specimen.（6） Made the numerical simulation study for the numerical models of the shape, size andconfining pressure of different test specimens in the same condition with indoor creep test,explored the parameter variation for the sensitivity of creep characteristics, it providedreasonable evaluation and suggestion for the effect of these kinds of indoor rheological testand numerical test’s parameter variation to the rheological characteristics.