Experimental Study On Influence Of Heat Treatment Methods On Mechanical Properties Of Granite

After the deep hot rock and geothermal resources mining,nuclear waste storage project and underground geotechnical engineering structure are subjected to fire,the rock is under the effect of high temperature,and the temperature will affect the physical and mechanical properties of the rock.Therefore,the in-depth study of the change of physical and mechanical properties of granite after high temperature heat treatment and the effect of different heat treatment methods on the physical and mechanical properties of granite have great scientific significance for practical engineering,and can provide technical guidance for practical engineering.In this thesis,the granite is heated and cooled by a muffle furnace.The density and porosity test,acoustic wave test,and X-ray diffraction test are used to study the physical properties of the granite for the heating and cooling by stages treatment.Study on mechanical properties of staged cooling granite after high temperature by conventional triaxial compression test.The physico-mechanical properties of granite cooled by rapid water cooling after high temperature heating are compared,and the effect of two different cooling methods on the physical and mechanical properties of granite is analyzed.The specific conclusions are as follows:(1)The increase in porosity of the granites for the heating and cooling by stages treatment is relatively uniform,while the porosity of the rapidly water-cooled granites increases significantly after 500 °C.(2)The mechanical properties of granite for the heating and cooling by stages treatment and granite for high temperature water cooling can be compared.Because the cooling rate of water-cooling is too fast,a temperature difference is generated inside and outside the granite,resulting in temperature stress.Specifically,the elastic modulus and peak strength of the rapidly cooled water-cooled granite sample after high-temperature heating have been improved compared to the step-by-step cooling of the granite sample after high-temperature heating.(3)Temperature stress at the heat treatment temperature of less than 500 °C increases the mechanical properties of granite specimens.When the heat treatment temperature is higher than 500 °C,the mechanical properties can be basically ignored.