Research On Dynamic And Static Mechanical Properties Of Marble Under High Temperature Conditions

At present,shallow mineral resources can no longer meet the needs of human resources,the exploitation of deep resources has become an inevitable trend of mineral resources development at home and abroad,but with the continuous deepening of mining space,The geological environment of rock engineering is becoming more and more complicated.Deep rocks are usually in complex geographical environment with "three heights and one disturbance"(high ground stress,high ground temperature,high karst water pressure and strong excavation disturbance).In the study of dynamic mechanics of deep rock at high temperature,temperature is an important factor affecting the physical and mechanical properties of rock.Complex physical and chemical changes will take place in the interior of rock under high temperature,which leads to different physical and mechanical behaviors of rock under high temperature than at room temperature.It is necessary to consider the influence of temperature and external load when the local protection works are affected by explosion,earthquake and sudden fire.It is necessary to study the dynamic mechanical properties of rock under the interaction of temperature and impact load,whether it is the evacuation of disaster personnel or the post-disaster restoration of underground civil air defense project,which requires further study on the dynamic mechanical properties of rock under the interaction of temperature and impact load.In this paper,the dynamic and static mechanical properties of marble subjected to high temperature are analyzed by mechanical experiments under static and static loading and microstructure characteristics of marble.The main contents of the study are as follows:1)the basic parameters of marble specimens at various temperatures are measured.Finally,the experiments of static loading and compression and splitting tensile test of marble specimens cooled at different temperatures were carried out by using YAW-2000 testing machine.2)the dynamic compression and splitting tensile tests of high temperature marble specimens were carried out with SPHB apparatus.The stress-strain curves of high temperature marble and its dynamic mechanical properties,such as compressive strength,tensile strength,peak strain and elastic modulus,were analyzed.3)the mineral composition of marble subjected to high temperature was analyzed by XRD technique,and then the microstructure of impact fracture after high temperature was scanned by SEM.Through the analysis of mineral composition and microstructure of rock,the damage evolution process and deformation and failure mechanism of rock are studied systematically and comprehensively.The main results are as follows:1)the dynamic and static physical and mechanical properties of high temperature marble is obtained through laboratory experiments.The dynamic and static peak strength and elastic modulus of marble decrease with the increase of temperature and the peak strain increases with the increase of temperature.The failure of marble changed from brittle failure to ductile failure.2)the study shows that the failure mechanism of high-temperature marble is mainly caused by micro-cracks,particle gaps and other micro-defects,such as initiation,propagation and decomposition of mineral composition,damage of crystal structure,trans granular cracks and intergranular failure.According to the experimental results of macro-and micro-parameters,the response characteristics of micro-macro parameters of marble samples under different temperatures are in good agreement.