Abstract
To explore the tendency of rockburst, a similar material ratio was optimised based on white sandstone. Quartz sand, iron powder, gypsum, cement, retarder, and a water-reducing agent were used as the main materials. The orthogonal test design principle was used to determine the four-factor and four-level orthogonal test design with the quartz sand content, iron powder content, gypsum-cement ratio, and sand particle size as the influencing factors. Uniaxial compression tests and tensile tests were conducted on similar material models. The tensile strength and elastic modulus were analysed, the significance of each influencing factor was investigated, and the test results of the similar materials were fitted. The optimal ratios of the similar materials of white sandstone were found to be quartz sand content of 36%, iron powder content of 1.9%, gypsum-cement ratio of 1.8 : 1, and sand particle size of 2–4 mm. The physical and mechanical properties of the similar materials were consistent with those of white sandstone. The mechanical properties of the similar materials were compared with those of the original rock. By judging the rockburst propensity and verifying the index, it is concluded that the similar materials can effectively simulate the characteristics of white sandstone, which is an ideal similar material of rockburst, and they all show strong rockburst propensity. The rock specimens with optimal proportions were produced, and the internal energy changes and rockburst mechanisms of the model at different temperatures were discussed. The results show that the rockburst process is closely related to energy, such as thermal energy and elastic strain energy, and the rock failure process can be divided into three main stages: energy accumulation, microcrack formation and propagation, and crack penetration and bursting. It provides an experimental basis for the preparation of rockburst similar materials that are more in line with the actual situation of the project and provides a basis for discussing the energy criterion of rockburst.
Highlights
Rockburst refers to the sudden release in strain energy accumulated in brittle rock masses, resulting in spontaneous failure of the rock
According to the rockburst tendency judgement method [14], we examined whether the similar materials meet the rockburst characteristics of white sandstone and analysed the rockburst mechanism based on the energy theory under different temperature changes [15], which provides a reliable guarantee for subsequent tests. is study lays the foundation for research on the geometric characteristics of deep underground white sandstone and reveals the generation mechanism and evaluation method of rockbursts. is study can further improve the deficiencies in the study of rockburst failure characteristics and failure mechanisms under thermal-mechanical coupling conditions and provide a certain theory for rock mass excavation and construction under the same or similar geological conditions in actual engineering projects; it provides a new type of measure for real-time heating of rocks
Analysis of Factors Affecting Compressive Strength. e relationship between the compressive strength of the similar material specimens and the levels of the four listed factors is shown in Figure 7. e abscissa represents the different levels of quartz sand content, iron powder content, gypsum-cement ratio, and sand particle size, and the ordinate represents the compressive strength of the specimens of similar materials
Summary
Rockburst refers to the sudden release in strain energy accumulated in brittle rock masses, resulting in spontaneous failure of the rock. According to the rockburst tendency judgement method [14], we examined whether the similar materials meet the rockburst characteristics of white sandstone and analysed the rockburst mechanism based on the energy theory under different temperature changes [15], which provides a reliable guarantee for subsequent tests. Similar materials of white sandstone were prepared, and uniaxial compressive strength and tensile strength tests were carried out. Sixteen sets of tests are designed, and each set of tests prepares three test pieces, a total of 48 test pieces It was conducted on specimens with similar material proportions by using a TAW-2000 electrohydraulic servo rock testing machine, and the tensile strength of the specimens was calculated according to equation (2).
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