Experimental validation and fracture properties analysis on wedge splitting concrete specimens with different initial seam-height ratios

摘要

In order to study the fracture properties of non-standard concrete wedge splitting tensile specimens with different initial seam-height ratios and the impact on concrete fracture toughness based on aggregates cohesive force, five groups non-standard concrete wedge splitting specimens with different initial seam height ratios as 0.2, 0.25, 0.3, 0.35 and 0.4 were designed and constructed for the experiment. Based on double-K fracture model and fictitious crack model, a new fracture toughness calculation model for non-standard concrete wedge splitting tensile specimen with different initial seam height ratios was built. The results showed that: the value of initial cracking load P_(ini) and unstable fracture load P_(un) decreased gradually with the increase of specimens' initial seam height ratio. With the increase of seam height ratios, the value of the critical effective crack length a_c showed a linearly increasing trend, but the subcritical crack propagation length Δa_c showed a decrease trend. The unstable fracture toughness K_(IC)~(un) and the cohesive toughness K_(IC)~c were affected by seam height ratios, decreased with initial seam height ratios increasing, and the initial fracture toughness K_(IC)~(ini) was independent of it that could be treated as material constant. When calculating the initial fracture toughness K_(IC)~(ini), the model in this paper could eliminate the errors caused at the moment of determining initial cracking load P_(int), which proved its advantage. For the specimens with smaller initial seam height ratio, its fracture features was influenced by maximum tension stress and showed some shearing failure.