Experimental Study and Numerical Simulation on the Influence of Specimen Size on Failure Characteristics and Mechanics of Plastic Concrete Under the Uniaxial Compression Test

In this paper, uniaxial compression tests and numerical simulation were conducted on specimens of five sizes, and the influence of specimen size on the failure characteristics and mechanics of specimens was studied. The results show that when the bottom size of the specimen is the same, with the increase in the height-width ratio of the specimen size (from 1 to 3), the peak stress of the specimen gradually decreases, but when the decrease is greatly reduced, the concentration of contact force chains in the model increases. The failure mode of the specimen changes from tensile failure to shear failure, and the distribution of cracks changes from multiple vertical cracks uniformly to a concentrated main oblique crack. The failure characteristics change from the overall failure to the serious failure of the near stressed end of the specimen, while the far stressed end is not failure or slight failure. When the height-width ratio of the specimen is the same, with the increase in the overall size, the peak stress decreases, and the dense vertical cracks change into a small amount of concentrated oblique cracks, and the integrity of the specimen and model is better. There is a good effect using PFC2D software to simulate the crack evolution and failure characteristics of plastic concrete.