Experimental Study on Acoustic Emission and Resistivity Response of Sandstone under Constant Amplitude Cyclic Loading

Abstract

A lot of engineering practice shows that, during the construction and operation of rock mass projects, in addition to the static load, the rock is more subjected to cyclic load. Constant amplitude cyclic load is one of the simpler cyclic loading methods. The damage of rocks gradually accumulates under the action of periodic cyclic load, and finally, fatigue damage occurs, which affects the stability of the project. Therefore, it is necessary to study the mechanical properties of the rock under the action of constant amplitude cyclic load. Acoustic emission (AE) parameters and resistivity are both sensitive to the damage process of the rock and can well describe the damage evolution law of the rock. Under the action of constant amplitude cyclic loading, different loading conditions, different state specimens, and so on, factors will make a big difference to the AE signal and resistivity, such as the difference in stress amplitude, loading rate, and saturation. Therefore, in this paper, the typical sandstone in the Chongqing area is taken as the research object, the AE characteristics and resistivity characteristics of sandstone under different test conditions such as different stress amplitude, different loading frequency, and different saturation are tested, and the evolution of AE is found. It also has a three-stage rule: in the initial stage, the deformation is faster and the AE signal is strong; in the constant velocity stage, the deformation develops slowly and the AE signal is also stable; in the acceleration stage, the deformation develops sharply and the AE signal also becomes more intense. With the increase of cyclic loading stress amplitude, or the decrease of cyclic loading frequency, or the decrease of rock sample saturation, the acoustic emission signal generated in each cycle will be stronger. The resistivity as a whole shows a rapid decline in the loading phase and a rapid rebound in the unloading phase. The changes in resistivity at different stress amplitudes show differences in the first few cycles; the overall change trend of resistivity at different frequencies is consistent, but the rate of change increases with decreasing frequency, and the variation trend of resistivity is very different under different saturation.

Characteristics of Resistivity Variation in Deep Granite and In-Situ Detection Applications

“…The resistivity variation with stress during the loading process is shown in Figure 13(a) and (b), while the resistivity variation during complete loading and unloading of the specimen is shown in Figure 13(c) and (d). The specific relationship between resistivity and stress variation is as follows [27,28] :…”

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

“…On the other hand, cyclic loading significantly affects the physical properties and mechanical response of granite. 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].…”

Mechanical Properties of Metasandstone under Uniaxial Graded Cyclic Loading and Unloading

“…J. Guo studied the acoustic emission signal characteristics of igneous rocks with different water content under cyclic loading and unloading [8]. K. Wang studied the acoustic emission parameters and resistivity characteristics of sandstone with different saturation under constant amplitude cyclic load [9]. J. Wu studied the acoustic emission signal characteristics of concrete cube specimens having different sizes under cyclic loading and unloading [10].…”