| The mechanical properties of rock impacted by the factors, such as: erosion bygroundwater, temperature changes and initial damage, have been studied in this paper.The analytic expression of the stress components and the maximum shear stress at thecrack tip were deduced.In the actual project, the complex components of rock material are taken intoaccount, a large number of micro and macro cracks are existed in the rock internal, andit often works in a variety of harsh environments, so it is necessary to analyze theinfluence of the natural environment work to the mechanical properties of the rock. Forexample, the mechanical properties of the rock are seriously impacted by theunderground wastewater erosion, the freeze-thaw cycles in cold regions and hightemperature environment, and the durability of rock are severely tested by the initialinjury and numerous micro-macro cracks exist internal. Since the above factors havebeen taken into account, the following four aspects are studied in this paper:(1) The crack of the actual rock material are simulated by using white cement tomade0°,15°,30°,45°,60°,90°these different angles of test block crack in thispaper.The uniaxial compression test of the test blocks in different fracture inclinationare performed, it was shown when the crack angle was change from0°to45°, thedestruction of the test block was closer to shear failure with the increase of cracksangles, the strength of the test blocks decrease with increasing of crack inclination.When the change of inclination is60°~90°, the destruction of the test block is closer totensile failure with the increase of cracks angles. It was shown that the rock strengthwas least when the crack inclination was45°, so in actual project when the crackinclination was45°should be paid special attention. Base on the plane stress inversemethod, the crack angle stress component of the rock test block and the maximumanalytical solution of the shear stress have been derived, a theoretical basis for futurepractical engineering have been provided. Finally, with the finite element software-ANSYS, the shear stress and the displacement of the test block rock when theinclination were0°,15°,30°,45°,60°,90°have been analyzed.(2) The rock was always initially damaged in the actual project, so it wasnecessary to study the mechanical properties of the rock with initial damages. In thispaper, the initial compressive strength of the rock was accounted in advance,then the pressure containing10%,30%,50%,70%,80%and90%of the ultimate compressivestrength are given to the rock. By the freeze-thaw cycle tests and uniaxial compressionexperiments, the damages of the rock in the traditional cyclic loading and after the lowtemperature freeze-thaw cycles are compared, the similarities and differences of thesetwo damages are obtained, the rock damage model was established under differentconditions, the influence of the initial damage on the behavior of risisting freeze-thawwas analyzed.The result can provide a reference value to the research of the freeze-thawdurability of the rock with initial damages.(3) For the rock which in the underground storage environment of highlyradioactive nuclear waste and suffered sudden to high temperature (such as fire), thephysical and mechanical properties change in different high temperature and highpressure need to be mastered in order to definite the mechanical properties of the rock inpractical engineering accurately. The basic physical and mechanical parameters of therock under freeze-thaw cycles and under high temperature and pressure, as well asfailure criteria and damage mechanism of the rock have been studied by domestic andforeign scholars in long-term, and certain results have been achieved. But in actualproject, the rock material often subjected to high temperature and low temperaturefreeze-thaw damage, the rock damage characteristics under a variety of environmentaleffects is more complicated and uncertainty, it takes a more serious impact on thedurability and stability of the rock. The rock impacted when a variety of factors workat the same time have been studied in this paper. The results that the mechanicalproperties of the rock deterioration with the heated temperature increased have beendrawn through the test of rock material under freeze-thaw cycles after high temperaturetreatment. It is shown that the compressive strength of granite get lower with the heattemperature increases, it did not change significantly when the temperature is less than300℃, but the mechanical properties of the rock is very unstable with a sharp declinein peak stress when the temperature at300℃~400℃and500℃~600℃, so it shouldbe paid great attention in actual engineering when the rock expose to these temperatureranges.(4) Four different concentrations of nitrate solution were used to simulate industrialwastewater in the actual project and used400degrees high temperature treatment of therock to simulation the rock in the high-level radioactive nuclear waste in the actualproject. In this paper, the variation rule of the rock quality,peak stress and peak strain under the influence of freeze-thaw cycle at0%,1%,3%,5%four concentrations ofnitric acid and high temperature was studied by experimental tests. The results showedthat the rock under the action of multiple factors in the freeze-thaw corrosion damage ismore serious。Based on the concept of damage mechanics of Rabtnov, damage variableD curves could be gotten and the relationship between the degradation of granite’smechanical properties and the concentration could be revealed, which provide someexperimental and theoretical basis for the further study of the mechanical propertiesunder the freeze-thaw cycling conditions.Based on the experimental research, the damage, deformation, durability anddestruction law of the rock impacted by many factors, such as: freeze-thaw cycles,temperature changes, the initial damage and cracks angle, have been summarized. Animportant guide to solve rock projects problems in recent practical have been providedby the study of this problem. |
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