| How to evaluate damage caused by the rock mass quality degradation has become a hot issue of large engineering construction. In this paper, based on supervisor's national natural science fund project (NO.4127233), "a class of asymmetric development of deep unloading formation evolution mechanism" to the right bank of Jinsha river Yebatan fresh Plagioclase granite as the research object, To explore "rupture" deep deformation in the development process of rock damage evolution law for the purpose, through conventional triaxial addition, unloading, laboratory test and cyclic triaxial growth, unloading test, Synchronous acoustic emission collection, to get the assignment of different water status under different confining pressure and deformation and failure characteristics of Plagioclase granite and the acoustic emission change rule, analysis the damage evolution law, the main research results are as follows:(1) Compared with the conventional triaxial compression condition, the loops and uninstall compression under the condition of elastic modulus have significantly reduced, and with the increase of confining pressure reduces the amplitude is greater. Show that under the effect of circulation and uninstall, Plagioclase granite strength degradation are more likely to happen, and with the increase of confining pressure this phenomenon is even more significant.(2) Compared to natural, the circulation of the two kinds of saturated and unloading test results, in 5 mpa under confining pressure, peak compressive strength by percentage is 13.84%;Fall in 10 MPa under confining pressure, percentage is 7.99%;Fall in 20 MPa under confining pressure, percentage is 10.58%;Fall in 30 MPa under confining pressure, percentage of 15.89%.This shows that the existence of groundwater on the mechanical properties of rock mass degradation is more obvious, and with the increase of confining pressure its degradation effect is more significant.(3) In the conventional triaxial compression test.Peak curve before the confining pressure of 5 MPa,10 MPa natural specimens, the peak after the deformation and failure type development mode in ?, under 30 MPa confining pressure I type.In cyclic triaxial test on growth and uninstall, natural samples with full water samples before the peak of plastic deformation quantity is very small, showing obvious brittle characteristics.After its peak are in ? type the deformation mode.(4) In the conventional triaxial compression test and cyclic triaxial unloading test of rock burst nature with strong shear fracture characteristics.With the increase of confining pressure, the sample of the main crack Angle and principal stress increases gradually, but generally between 15 °?35 °, second crack and overall Angle of principal stress increases gradually, and gradually transition from tensile failure to shear failure, it shows that the sample shear component proportion increase gradually.(5) Acoustic emission characteristics of conventional triaxial:pressure and the elastic deformation stage, sound FaShi number is few, compared with the whole deformation process of the total number of events, the proportion between 1% 1%;Stability of crack development stage, the growth of the number of acoustic emission events have certain, value is between 3.5%?3.5%, compared to the previous two phase proportion increase;Cracks crack instability development phase, the value is stable phase of 10 times as much as 20 times, even dramatically increase the number of acoustic emission events.(6) Acoustic emission characteristics of cyclic triaxial:acoustic emission blank period, accumulated acoustic emission ringing count curve almost flat, minimal value, average between 5%.Acoustic emission growth at a constant speed:accumulated acoustic emission ringing count rise at a constant speed curve ladder shaped over time, average value of 15%.Acoustic emission accelerated growth:accumulated acoustic emission ringing count curve showed a trend of accelerated growth over time, the average value of 80%, the number of acoustic emission events are mainly concentrated in this stage.Natural sample cycle early will appear continuously or continuously Kaiser effect, when more than one cycle stages, began to have a Felicity effect, have Felicity effect full water sample only.(7) Growth and unloading conditions, such as cyclic triaxial quartz diorite damage evolution process:a) early damage, the cumulative residual strain and the total dissipation can rock to 0, and basic negligible value, this phase within the rock rupture point is not produced, damage value is 0;b) damage to the stationary phase, minimal residual strain variation, dissipation can slow growth, accumulated acoustic emission curve is nearly flat linear ringing counts, value KN is between 0.1%?0.1%, the rock has new burst point, damage began to accumulate, but compared with the whole failure process, the stage of damage value can be ignored.c) damage growth at a constant speed, the residual strain decreases, dissipation can rapid growth, accumulated acoustic emission ringing count ladder shaped curve constant speed increase, the values KN between 4%-20%, internal leak-off has lots of new generation, rock burst point gradually formed a new crack, the number of events proportion coefficient is bigger also, the beginning of its numerical can directly cause damaged) damage to accelerate the growth of residual strain increases gradually, the dissipation can rapid growth, accumulated acoustic emission ringing count curve ladder shaped speed increase, the value KN is between 77%?96%.Rock internal leak-off has lots of new generation, to form a new crack or original crack expands gradually, assemble a macroscopic crack, eventually to penetration failure surface, lead to the whole of the rock damage, damage accumulated rapidly at this stage, this stage of leak-off basic accounts for 4/5 of the entire stage, rock's damage fracture mainly through this stage. |
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