Experimental Investigation On Fracture Of Normal Concrete Under The Combined Effects Of Water Pressure And Axial Force

With the great development of the technology of water electric power, the constructionof big reservoirs and high dams are more and more. The concrete dams which are underconstruction or proposed have developed to level300meters, compared with100m highdams, when the current specification was adopted to design the high concrete dam, the maindifference is the high pressure water splitting. both the temperature control problems and theload all can cause the gravity dam’s damage fracture, it will become serious along with theincrease of dam’s height, especially when the high water pressure act upon the crack. one ofthe core issues is the water splitting reaction on concrete, so it’s nesessary to study thisproblem in depth.For the normal concrete dam that is under reservoir condition may appear thephenomenon of hydraulic fracturing,"the experimental investigation on crack of normalconcrete under the combined effects of water pressure and axial force" is done. According tothe different angles between the initial crack and the axial force,24pieces of specimenswhich have the same size (450mm450mm900mm) but different initial crackAngles (0degree,30degree,45degree,60degree) are made, the specimens in one sort ofdegree have6pieces, the I-II mixed mode fracture criterion of concrete was studyed byusing two kinds of ways which are under the constant water pressure butvariable axial tensionload or under the constant axial load but variable water pressure.According to the experiment data, the load-strain curves included the load displacementcurves are all drawn, what’s more, stress intensity factors on the crack tip are also calculated,the crack angles are measured. For the I-II mixed mode fracture of concrete, strains anddisplacements increased along with the increasing of the loading; Crack Angles increasedalong with the increasing of the initial crack Angles; I-II mixed mode fracture of concretehave a crack fracture, the steady expansion and breaking process, bofore the specimens’breaking process, there exists a stable crack propagation process for a period of time, once inthe breaking time, the cracks will rapidly expand until broken.The concrete fracture criterion curve for the I-II mixed mode fracture of concrete whichis fitted by the experiment datas accords with quadratic curve model, WhenK (I, II) K(I, II)C,Specimens are in a safe area, they will not break, or, they will buck, Moreover, by comparingwith the criterions that have been introduced in front, we can find that our criterion is mostclose to the(εθ)maxcriterion. By contrast with several other criterions, our criterion isrelatively conservative and safe.