Proportion test of similar materials of coal rock with low strength rockburst tendency

LIANG Weikang; HUA Xinzhu; LI Chen; PAN Weipeng; XIE Yuhang

doi:10.11799/ce202411020

Abstract：Physical simulation test is one of the important scientific means to study rock burst of coal.Developing similar materials with low strength and high rockburst tendency is the key to physical simulation of rockburst.Aiming at meeting the material performance requirements,the rockburst energy index and brittleness index were introduced,and four factors including calcium carbonate content,barite powder content,gypsum cement mass ratio and water content were selected by orthogonal experimental design method and sensitivity analysis method.A total of 25 groups of orthogonal ratio schemes with 4 factors and 5 levels were designed.Uniaxial compression and acoustic emission characteristic experiments were carried out to obtain stress-strain curve and acoustic emission evolution characteristics of the samples,determine the performance parameters of each group of samples such as strength and rockburst energy index,and compare and analyze the variation rules of each test parameter under different levels of four influencing factors.The rockburst energy index and brittleness index were used as screening conditions to select similar material ratio schemes.The experimental results show that water content and calcium carbonate content are the main factors for the preparation of low-strength,high-impact and strong coal-rock similar materials,and the brittleness degree and strength of similar materials can be adjusted by changing the mass ratio of gypsum to cement.Taking the rockburst energy index KE≥1.5 and brittleness index BIzhou≥0.2 as the selection criteria,six groups of low-strength and high-rockburst tendency materials were obtained.When the water content is 19%～25%and the calcium carbonate content is 26%～32%,the rockburst tendency of the prepared samples can meet the test requirements.During sample loading,acoustic emission events were not active before the yield stage,but after entering the yield stage,the ringing count increased sharply and high energy damage occurred,and the trend of"smooth transition and sharp rise"occurred before and after the yield stage.