Experimental Study On Oblique Section Shear Behavior Of Reinforced Coal Gangue Concrete Beams

Coal gangue is the mixture produced in the process of coal mining.Because of its low utilization rate and low consumption channels,it has become the largest solid waste in China.With the rapid development of economy and the acceleration of urbanization,the disposal of solid waste is imminent,and the treatment and recycling of coal gangue needs to be solved urgently.It is an extremely effective way for coal gangue resources to be recycled and utilized in engineering structures by using it instead of natural coarse aggregates for concrete allocation.This not only solves the problem of utilization of coal gangue in coal mining,but also improves the utilization rate of resources.At the same time,it can also save natural gravel aggregate and avoid the environmental damage caused by over-exploitation of the rockIn this paper,the coal gangue in the Shenmu area of Shaanxi Province is used as raw material,which replaces the natural crushed stone coarse aggregate in proportion,and is arranged into gangue concrete with the substitution rate of 0%,40%,70%and 100%respectively.Ten coal gangue concrete beam shear specimens were made,and the shear resistance of the coal gangue concrete beams was studied by taking coal gangue replacement ratio,shear span ratio,stirrup ratio and bending reinforcement as the main influencing parametersFirstly,the compressive test of cubic coal gangue concrete was carried out,and the compressive strength,tensile strength and initial elastic modulus of coal gangue concrete with different substitution rates were obtained.The results show that the coal gangue concrete can meet the target strength requirements at different replacement rates according to the designed mix ratioSecondly,the shear performance test of coal gangue concrete beams is carried out to measure the strain of steel reinforcement,the strain of coal gangue concrete and the deformation of the beam.The cracking load of the oblique section in the bending and shearing area and the ultimate load of the test piece were observed.During the test,the maximum oblique crack width and the main oblique crack inclination angle of each stage were measured.The occurrence,development,distribution and failure mode of the cracks of the specimen were analyzed.The failure mechanism and failure mode of the shear specimens of coal gangue concrete beams were studiedThirdly,the relationship between load and steel strain,concrete strain and deformation is analyzed.The effects of different coal gangue replacement rate,shear span ratio,stirrup ratio and bending reinforcement on the mechanical behavior,crack development and deformation performance of coal gangue concrete beam are discussed Based on the cracking model of inclined section of concrete beam proposed by some scholars,the calculation formula of the oblique section cracking load of coal gangue concrete beam is obtained by mathematical analysis softwareForthly,according to the test results and the analysis of the factors affecting the shear capacity of coal gangue concrete beams,the shear capacity reduction coefficient of coal gangue concrete beam is introduced in this paper,and the relationship between the reduction factor and the replacement rate of coal gangue is obtained.Based on the applicability of the shear theory and calculation model to the shear mechanism and failure mode of coal gangue concrete beam,the formula for calculating the shear capacity of the inclined section of coal gangue concrete beam is established on the basis of the modified pressure field theory and the traditional application habit of the shear strength formula of concrete beams.