| With the rapid development of economy and deep engineering construction,the construction of tunnel excavation,mine wall support,water conservancy and hydropower projects,the mining of important resources such as deep natural gas,oil,coal and the deep burial of highly radioactive nuclear waste in nuclear power plants are increasing.In addition,these underground rock projects not only suffer from the erosion of the complex groundwater environment around them,but also bear the influence of mechanical excavation,blasting excavation,earthquake vibration and other dynamic loads,which makes the construction and stability of underground rock projects a hidden danger.The groundwater in most areas is alkaline,therefore,the dynamics performance test of sandstone under alkaline solution-kinetic coupling can provide a certain reference basis for the study of the long-term stability and safety of underground engineering.The specimens used in this paper were taken from Dingji coal mine and Gu Bei coal mine roadway sandstone of Huainan Mining Group,Anhui Province,respectively,and the same p H strong alkaline solution was used to carry out corrosion tests at different times and different p H alkaline solutions were selected to carry out corrosion tests at the same time.The basic physical parameters such as mass,volume and density were measured on the sandstone specimens before and after corrosion,and the changes of p H value of corrosion solution were measured and recorded regularly.The details are as follows.1.The p H of the water chemical solution was analyzed as a function of time;the changes of the basic physical parameters of the sandstone specimens were measured after corrosion with strong alkali solutions of p H 11 for different corrosion times and after corrosion with water chemical solutions of different p H values for 28 d,and were compared with the uncorroded specimens.2.Static uniaxial compressive tests were performed on the sandstone specimens to obtain their basic parameters such as uniaxial compressive strength and Young’s modulus,followed by dynamic compression tests at different corrosion times(0d,1d,3d,7d,14 d,28d)undergoing corrosion with strong alkali solution(p H=11).The effects of corrosion time on the dynamic stress-strain curves,dynamic compressive strength,dynamic elastic modulus,dynamic peak strain,average strain rate and impact compression damage morphology of the sandstone specimens were investigated and analyzed.3.Brazilian dynamic splitting experiments were conducted on sandstone specimens subjected to different corrosion times(0d,1d,3d,7d,14 d,28d)by strong alkali solution with p H 11,and the effect of corrosion time on the dynamic stress-strain curve,dynamic tensile strength,dynamic peak strain and splitting tensile damage of sandstone specimens was analyzed in the context of energy dissipation.The effects of corrosion time on the dynamic stress-strain curves,dynamic tensile strength,dynamic peak strain and splitting tensile damage morphology of sandstone specimens were analyzed from the perspective of energy dissipation,and capture the dynamic tensile crack development process of sandstone by using high-speed camera.4.Separate Hopkinson compression bar equipment was used to conduct dynamic compression tests on sandstone specimens under constant impact air pressure after 28 d of corrosion by hydrochemical solutions with different p H values(p H=7,8,9,10,11,12),and electron microscopy scanning(SEM)tests and X-ray diffraction(XRD)tests were carried out on the crushed specimens after impact to analyze the effects and patterns of solution p H changes on dynamic stress-strain curves,dynamic elastic modulus,dynamic compressive strength,dynamic peak strain,and dynamic compression damage morphology of sandstone specimens by combining micro-level and macroscopic perspectives.Figure [47] Table [4] Reference [116]... |
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