Experimental Study On Micro Damage Evolution Of Rock Caused By Rheological Disturbance Effect

In deep mining activities,the rock is in the state of high ground stress,and the rheological problem is prominent.At the same time,it is affected by various dynamic load disturbances,which makes the rheological problem more significant.Most of the existing studies determine whether the rock enters the “ strength limit neighborhood ” through the variation characteristics of macroscopic variables such as stress and strain of rock.Using nuclear magnetic resonance technology to study the rock ' strength limit neighborhood ' range and rock rheological disturbance effect is relatively small.In view of the above problems,the single-and three-axis rheological disturbance effects of rock were studied by means of nuclear magnetic resonance test.The micro-discriminant standard of rock ' s ‘ strength limit neighborhood ' range and the corresponding damage constitutive model were established,and the law of rock rheological disturbance effect from the micro perspective was obtained,so as to enrich the theoretical system of rock rheological disturbance effect.Experimental results show that :(1)The damage evolution test of uniaxial rheological disturbance effect of rock was carried out.The damage detection of rock within and outside the ‘ strength limit neighborhood ' was carried out by using the nuclear magnetic resonance technology.The T2 spectrum curve,pore size distribution and nuclear magnetic resonance imaging spectrum of rock were obtained,and the quantitative analysis was carried out.It was found that the T2 spectrum curve of rock outside the ‘ strength limit neighborhood ' did not shift after disturbance,while the T2 spectrum curve of rock within the ‘ strength limit neighborhood ' had a large shift,indicating that the T2 spectrum curve could reflect the within and outside the ‘ strength limit neighborhood '.The change of internal void structure of rock within and outside the ‘ strength limit neighborhood ' after disturbance could be clearly seen by observing the nuclear magnetic resonance imaging map.(2)The damage evolution test of triaxial rheological disturbance effect of rock was carried out.The damage detection of rock under different confining pressures was carried out by using nuclear magnetic resonance technology.The T2 spectrum curve,pore size distribution and nuclear magnetic resonance imaging map of rock under different confining pressures were obtained and analyzed.From the perspective of microscopic damage,the criterion of whether the rock enters the ‘ strength limit neighborhood ' under different confining pressures was established.(3)The damage evolution law of rock in the neighborhood of strength limit is studied,and it is concluded that the rock in the neighborhood of strength limit accelerates the damage of instantaneous elastic modulus of rock rapidly with the increase of disturbance times,and the disturbance is proportional to the instantaneous strain of rock.At the same time,the parameters of rock rheological data under different disturbance times are identified,and the rheological damage constitutive model is established.The test results are in good agreement with the fitting curve,indicating that the model is reasonable.The research results of this paper make up for judging whether the rock enters the range of ' strength limit neighborhood ' from the microscopic point of view,enrich the theoretical system of ' rock creep disturbance effect ',and provide a basis for subsequent related research.