Experimental Study On Split-tension Fracture Of Fully-graded Concrete Wedge

In the current research of fracture mechanics,most experimenters use the simplified test method,such as wet screen method,small test piece method,etc.but it is also reasonable,after all,pouring large size fully graded concrete specimen is time-consuming,energy consumption,and consumables,so there are few researchers in the total grading concrete breaking performance.Limited by the test conditions,the research on the fracture mechanics characteristics of fully graded concrete is still not systematic.The fracture mechanics characteristics of fully graded concrete are systematically studied,which provides a basis for the safety and stability evaluation of concrete structures.However,Concrete is a heterogeneous multi-phase composite material composed of coarse aggregate,fine aggregate and admixture.There must be some micro cracks or other defects during construction,maintenance and service.Under complex loads,these microcracks will occur under the action of complex loading and extension,and eventually lead to macroscopic cracks,until the failure of components.In order to explore the whole process of breaking and failure of full graded concrete,the law of crack expansion and energy consumption of concrete members was studied.So this paper uses more traditional measurement methods,namely the wedge splitting test method.Based on the methods of physical test and theoretical analysis,the following aspects are carried out in this paper.(1)Aiming at the special needs of this test,we have independently designed a set of loading device for wedge splitting splitting test,including a loading frame and two load transfer plates.The concrete specimen,loading device and double support analysis of vertical load under the form of stress of the fracture energy,lay the foundation for full graded concrete wedge splitting fracture test.(2)pouring a series of four identical Jacobi(0.4)specimens with different height(200mm,1250mm,1500mm,1800mm)of concrete wedge splitting specimens,a total of 18specimens.During the test,the load crack opening displacement(P-CMOD)curve was collected,and the complete curve was fitted based on the exponential function to calculate the fracture energy G_f.According to the test data,the fracture toughness of the concrete double K is obtained.(3)By using the strain gauge method,the strain sheet is attached symmetrically around the tip of the prefabricated seam and on the extension line,and the starting load of the specimen is recorded by the strain hysteresis.Through the comprehensive analysis of experimental data,the whole process curve of P-?of some key points is obtained,in order to judge whether the test points are cracked or not.