Evaluation And Analysis Of Mechanical Parameters Of Coal And Rock Mass Based On Small Aperture Test

The stability and safety of all underground spaces depend on the effective acquisition of coal and rock mass parameters,especially for key underground projects such as roadway and tunnel,coal and rock mass parameters will provide the most basic data for engineering design,numerical calculation and theoretical analysis.At present,engineering rock mass parameters mostly rely on laboratory test and field experience method,and do not consider the influence of in-situ stress state and engineering excavation disturbance,which is separated from the actual engineering activities,and can not truly reflect the mechanical properties of coal and rock mass under engineering activities.Based on this,the team introduced and developed a set of in-situ test equipment and corresponding test methods,and carried out industrial application research,which has very important theoretical and application value for ensuring the rationality and reliability of engineering rock mass design and the effectiveness of engineering measures.In order to explore the relationship between the in-situ test of mechanical parameters of coal and rock mass and the indoor test results,four concrete samples with the proportioning strength of C20,C30,C40 and C50 were made,with the size of 2600 ×eight hundred × The diameter of the drill hole is 78 mm in the middle of the sample,which is used to test the elastic modulus and shear strength parameters of the drill hole;At the same time,the same strength specification of the indoor test sample,size 150 × one hundred and fifty × 12 300 mm specimens were used for uniaxial compression test;one hundred and fifty × one hundred and fifty × 16 150 mm specimens were used in the laboratory direct shear test.A total of 128 sets of small aperture test shear data,36 sets of elastic modulus data and 28 sets of mechanical parameters of standard test block were obtained.The results show that the cohesion C0 obtained from the laboratory direct shear test and the cohesion CB obtained from the borehole shear tester obey the linear function relationship,The relationship between the elastic modulus E0 obtained by uniaxial test and the elastic modulus EB measured by the borehole elastic modulus tester also obeys the linear function.The relationship between the mechanical parameters of the indoor samples under the conventional mechanical test and the small aperture test is preliminarily established.In order to obtain the spatial distribution law of roadway surrounding rock parameters,taking a mine roadway in the western mining area as the engineering background,a total of8 test boreholes are arranged,of which 2 Roof Boreholes and 2 coal wall horizontal boreholes are used for in-situ measurement of elastic modulus of coal and rock mass;Two horizontal boreholes of coal wall and two horizontal boreholes of rock wall are used for in-situ testing of shear strength parameters of coal and rock mass.The mechanical parameters of different coal and rock mass at the same position under in-situ stress condition are tested,and the spatial distribution characteristics of mechanical parameters of coal and rock mass at different depths and directions are obtained: the cohesion of coal is less than that of sandy mudstone,but the internal friction angle is greater than that of sandy mudstone,The results are in good agreement with the field sampling test results;The shear strength parameters of coal and rock mass(C ?)? The elastic modulus E increases with the increase of drilling depth.The research results provide a group of accurate,reliable and convenient geomechanical parameters of coal and rock mass,which lays a foundation for coal mining design and roadway surrounding rock control.This paper has 90 pictures,21 tables and 103 references.