| With the progress of science and technology,the space for human activities is deeper and wider,the number of mountain construction and deep construction increases,and more projects are carried out on rock foundations.Mechanical construction,drilling and blasting construction will impact on the concrete support structure,natural seismic wave,deep underground high ground stress conditions will also affect the rock-concrete structure.Currently still need further study in combination,for the development of rock and concrete combination structure dynamic performance under different thickness ratio,at the same time for related construction and provide some theoretical basis,different thickness than the dynamic mechanical properties of rock and concrete combination experiment research is of great significance.The sandstone with good integrity and uniformity in the deep underground of Anhui Huainan Dingji Coal Mine was selected in the experiment.The mass ratio of concrete used in practical engineering was cement: sand: stone: water = 1:1.5:3:0.58,the cement was 42.5 grade ordinary Portland cement,the sand was coarse sand,and the gravel particle size was 5-15 mm.The thickness,diameter and mass of the specimens were numbered and measured.The SHPB loading system is used to calculate the rock thickness of 0,5,10,15,20,25,30,35,40,45,50 mm,respectively,when the thickness of the composite is kept constant at 50 mm.That is,11 different rock to concrete thickness ratios(0:10,1:9,2:8,3:7,4:6,5:5,6:4,7:3,8:2,9:1,10:0).The dynamic uniaxial compression test and dynamic splitting test of rock-concrete composite specimens under the same air pressure were carried out,and the fragments after impact were screened and scanned by electron microscopy.The dynamic characteristics,energy dissipation and breakage of the composite specimens were analyzed.The research content is as follows:(1)On 11 different thickness than the combination of rock and concrete specimens,by using SHPB loading system for dynamic uniaxial compression test,analysis of different thickness ratio on the combination of dynamic compressive strength,dynamic modulus of elasticity,the influence of dynamic power parameters such as peak strain and the change law of energy dissipation and can absorb energy,transmission and average strain rate,the change rule of between dynamic compressive strength.(2)On 11 different thickness than the combination of rock and concrete specimens,by using SHPB loading system for dynamic Brazilian disc splitting test,analysis of different thickness ratio on the combination of dynamic tensile strength,the influence law of peak strain,change of the reflection,absorption and transmission of energy and can absorb energy,transmission and average strain rate,the change rule of between dynamic tensile strength.(3)The fracture morphology of 11 specimens of rock-concrete composite with different thickness ratios under dynamic compression and splitting under impact load was observed,and the relationship between the thickness ratio and the fracture condition was analyzed.The dynamic performance and energy dissipation of specimens were further explained through the fracture condition.(4)Broken after impact specimen were collected for screening test,calculate the average particle size,quantitative analysis was carried out on the specimen broken situation,choose suitable electron microscope scanning with fragments of rock and concrete respectively,observe 1000 times magnification specimen under the condition of apparent morphology,internal form analysis of the specimen from the microscopic view of dynamics and energy dissipation factors.Figure [43] Table [6] Reference [71]... |
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