Penetration Test And Mechanism Study Of Cracked Fiber Concrete Tunnel Segments

Generally,the reinforced concrete tunnel segments have insufficient performance in mechanical properties,impermeability and crack resistance,and the fiber concrete tunnel segments have good mechanical properties,excellent durability and other characteristics,which make up for the defects of reinforced concrete segments.In order to analyze the permeability of fiber concrete tunnel segments,the influencing factors of fiber concrete permeability coefficient were studied,and the permeability of fiber concrete under cracking conditions was analyzed.The following work was done in this paper.In this paper,the compressive strength of cubic and the compressive modulus of static compression are analyzed by the conventional mechanical properties test of fiber concrete.The influence of different fiber types and fiber content on compressive strength and elastic modulus is analyzed.The disc splitting test simulates the crack propagation of fiber concrete during normal construction and use,and analyzes the variation of the average crack width when the single-doped polypropylene fiber,the single-doped steel fiber,and the two fibers are mixed;The fiber concrete was subjected to a penetration test to measure its permeability coefficient.Through the analysis of the permeability coefficient of the cracked fiber concrete,the factors affecting the permeability of the cracked fiber concrete were summarized.Through a series of experiments and analysis,the following conclusions are drawn:1.The increase of the compressive strength of the single-doped polypropylene fiber is not significant,and the degree of improvement is about 5%;when the steel fiber is added alone,the compressive strength of the cube gradually increases with the increase of the steel fiber content.When the steel fiber content is 46.8 kg/m3,the compressive strength of steel fiber reinforced concrete is the largest;the compressive strength of mixed fiber reinforced concrete is better than that of concrete with a single fiber.2.Through the fiber concrete Brazilian disc splitting test,it was found that the crack width of the fiber concrete was reduced compared with the ordinary concrete.Among them,steel fiber and hybrid fiber have better crack resistance effect,and the largest reduction of crack is S1 steel fiber concrete with steel fiber content of 31.2kg/m3.3.The results of permeation test of cracked fiber concrete show that the permeability coefficient of polypropylene fiber decreases with the increase of fiber content,indicating that the impermeability of polypropylene fiber is improved.When steel fiber is added alone,the influence of steel fiber on concrete permeability It also showed a positive correlation change law,and the best impermeability was obtained when the steel fiber content was 78 kg/m3.4.Based on the theory of concrete fracture mechanics,the fracture parameters of cracked fiber concrete were introduced,and the correlation between permeability coefficient and fracture parameters was searched.The data analysis software was used to analyze the correlation curves of permeability coefficient and fracture parameters to obtain the permeability coefficient and A mathematical expression for both the fracture parameters.Through the introduction of the fracture parameters,the permeability quantification of the cracked fiber concrete was completed.Figure[59]table[12]reference[62]...