Experimental Study On Petrophysical And Mechanical Properties Of Shanxi Formation In Theperiphery Of Panji Coal Mine,Huainan Coalfield

In the future,coal will be the main energy support for the development of our national economy.With the gradual entry of coal mining into the deep mining stage,the influence of geotemperature and ground pressure on the coal mine engineering is becoming more and more serious,which puts forward higher requirements for the study of the physical and mechanical properties of the rock in the deep coal measures.In this paper,the rock structure of the Shanxi formation in the periphery of the pan Ji Coal Mine in Huainan coal field is studied.Through the selection of the site samples and the microscopic identification of the rock slices,the composition of the rock structure is analyzed.The physical properties of the rock density,the longitudinal wave velocity and so on,as well as the compressive tensile test under the conventional conditions,and the temperature conditions under the conventional conditions are carried out.The uniaxial compression test and the conventional three axis compression test were used to analyze the characteristics of the physical and mechanical properties of the rock in Shanxi group under various test conditions,and based on the results of the three axis test,the parameters of the rock damage constitutive model considering the confining pressure effect were solved.The research results have some guiding significance for roof management,roadway maintenance and engineering safety prediction of Shanxi coal seam mining.The main achievements are as follows:(1)The physical indexes of the same rock rock density,longitudinal wave velocity and other physical indexes,such as compressive strength,tensile strength,modulus of elasticity and Poisson's ratio,have high discreteness,which reveals the main controlling effect of the sedimentary characteristics of coal system on its physical and mechanical properties.(2)The temperature has a certain influence on the mechanical properties of coal rock.The compressive strength,modulus of elasticity and deformation modulus of each lithologic rock increase with the increase of temperature.The ratio of Poisson's ratio decreases with the increase of temperature;with the increase of temperature,the strength of coal rock rock is hardened and the strength of coal system rock increases.Composition and structure are the main reasons for the variation of some lithologic fluctuations.(3)The compressive strength,cohesive force and modulus of elastic modulus of sandstone increase obviously with the increase of confining pressure,and the internal friction angle decreases,and the deformation modulus shows the characteristics of first increasing and then decreasing.With the increase of confining pressure,the failure mode is changed from tensile to shear rupture,and the threshold of change confining pressure is about 15 MPa.(4)Based on the research results of the constitutive model of rock damage under uniaxial compression,based on the data of three axis compression test of fine sandstone,by analyzing the relationship between the parameters of the model and the confining pressure,the parameters of the damage statistical constitutive model of fine sandstone,considering the confining pressure effect,are solved.The comparison and analysis shows that the parameters are more reasonable.