Study On Failure Law Of Concrete Specimen Under Different Pressure

Static crushing technology is a new type of crushing technology.In the demolition of some supports and the demolition of deep foundation pit support,the action of external load should be considered.In this paper,the cracking effect of concrete under several different pressure loads is studied,the main contents are as follows:(1)The law of crack expansion under free(0MPa)condition:the reserved hole is a test block with circular hole,the time of the first crack is 0～0.5h later than that of the second slotted block,and finally 3～4 cracks are generated.The positions of cracks are relatively random.In the end,2～3 cracks appear in the sharp corner grooving test block,and the position is basically extended along the direction of grooving Angle.When the strength is C30 and the reserved hole is a double-cut slot,the maximum crack is generated and the crack width is 50mm.(2)The influence of the strength of concrete under pressure load(6MPa,8MPa,10MPa)and the way of reserved hole on crack propagation is studied.The following conclusions are drawn:under the condition of reserved hole shape and concrete strength is certain,the time of the first crack in test block increases with the increase of load,and the final crack width decreases with the increase of load.Under the same test block strength,the time delay of the first crack of the test block with circular reserved hole under load is 0.5～2h compared with that of the test block under free state.The longer the load is,the longer the time of the first crack is.Under the condition of a certain load and strength,the first crack in the groove reserved hole occurs 0～1h earlier than that in the circular reserved hole.After the reaction,the maximum crack width of the groove cut is larger than the maximum crack width of the circular hole.Under the condition that the reserved hole pattern is consistent and the load is constant,with the increase of the strength of the concrete test block,the time of the first crack is small,and the maximum crack width after the end of the reaction decreases with the increase of the strength of the test block.Under the action of load,the reserved hole of two groove has certain guiding function compared with the circular reserved hole.Under the load of 6MPa,the strength is C30,the groove cutting mode is double groove,the maximum crack is generated,the crack width is 6mm,and the first crack appears in 1h43min.(3)under the condition of the same pressure load and a certain strength,the effect of the reserved hole on the reaction temperature was compared.The test results showed that the reserved hole for groove cutting reached the maximum temperature 0.5～1h earlier than the circular reserved hole.Figure 122 table 52 reference 56...