Fracture Properties of Rock-Concrete Interface after Fatigue Loading

Abstract

To investigate the fracture properties of the rock-concrete interface after fatigue loading, the fatigue tests with the maximum loads of 60% and 70% of the ultimate load were first carried out under threepoint bending (TPB) loading. After 80000 fatigue loading cycles, the specimens were subjected to quasi-static TPB loading until failure. The fracture parameters including the nominal initial fracture toughness K ini 1C , the nominal unstable fracture toughness K un 1C , the critical crack length ac, the fracture energy Gf and the characteristic length lch were obtained based on the experimental results. The test results indicated that the interfacial crack did not propagate in the fatigue tests if the applied maximum fatigue load was lower than the initial cracking load under quasi-static loading. However, microcracks would occur and accumulate around the pre-crack tip during the fatigue process, which generates a larger damage area than that under the quasi-static load condition. The larger damage area absorbed more energy provided by the applied loading in the subsequent monotonic TPB tests, leading to the increases of the initial cracking load and the nominal initial fracture toughness. Accordingly, a distribution model of the nominal initial fracture toughness along the interfacial ligament was derived for the fatigued specimens. Furthermore, a crack propagation criterion based on the nominal initial fracture toughness was proposed and employed to simulate the fracture process of the fatigued specimens. The good agreements between the experimental and numerical results validated the proposed distribution model and the crack propagation criterion.

Effect of Cyclic Loading on Mode I Fracture Toughness of Granite under Real-Time High-Temperature Conditions

“…Recent findings indicated that the fatigue failure of rocks can be categorized into three distinct stages: the initial deformation stage, the constant deformation stage, and the accelerated deformation stage, as detailed in the studies of Wang et al [23,24]. Extensive research has been conducted to investigate the impact of cyclic loading on the fracture toughness of rocks [25][26][27][28][29]. The results indicated that the fracture toughness of the specimens experiences a noticeable decrease when subjected to cyclic loading.…”

Paris Law Based Modelling Of Mixed Mode Fatigue Crack Propagation In Concrete-Concrete Interface

“…The fracture behaviour of a bi-material interface under fatigue loading may exhibit greater complexity as compared to intact concrete due to the presence of mismatched material properties on each side of the interface. Shah et al [16] experimentally studied the effect of elastic mismatch on fatigue crack propagation and Zhao et al [17] conducted experimental investigation to examine the behaviour of the rock-concrete interface subsequent to prefatigue loading.…”

“…The recent notable efforts to expand the scope of the Paris' law to include mixed-mode crack propagation in metals [18] and plain concrete [17] shows that conventional compliance calibration approach becomes impractical in mixed mode condition, therefore there is a need to establish a new method to extend the Paris' law to accommodate interface fractures. In this paper attempt has been made to explore of this imperative research gap, the objective is to develop a generalised model based on Paris' law introducing the equivalent stress intensity factor (∆K eq ) instead of stress intensity factor in mode-I (∆K I ).…”