Quantitative Damage and Fracture Mode of Sandstone under Uniaxial Load Based on Acoustic Emission

Abstract

The damage degree and fracture mechanism of the rock are important to the bearing performance of the rock mass and the stability of the overlying structure. Most of the existing damage models for characterizing rock damage exclude the range of postpeak stress or do not consider the compaction and closure stage of the fracture, and the description of the quantitative damage of sandstone is not accurate enough. In addition, the description of the rock fracture mechanism under load is not exact enough. Aiming at the problem of quantitative damage and fracture mechanism of the loaded rock, this paper adopts acoustic emission (AE) to monitor the loading process of sandstone under uniaxial loading. In accordance with the characteristics of the AE signal, the loading stage of sandstone under uniaxial load is divided into three stages: initial hit stage, hit stability stage, and hit instability stage. By modifying the traditional damage model and combining the AE signals of the sandstone under the load, a modified damage mechanics model is obtained, which can fully express the entire loading stage. Furthermore, through the analysis of AE signals, the fracture mechanism of sandstone under uniaxial load is studied. The results show that the modified damage model can quantitatively describe the damage at different loading stages which include two areas including the fracture compaction closure stage and the postpeak stress stage. The failure and instability of sandstone under uniaxial load is mainly shear failure. The research results can provide a reference for the nondestructive testing of sandstone and engineering reliability in geotechnical engineering.

Mechanical Damage Test and Model Study of Layered Composite Rock Based on Acoustic Emission and DIC Characteristics

“…Zhang et al [7] studied energy dissipation and crack characterization in the sandstone fracturing process by using AE and DIC systems. Xu et al [8] investigated the fracture mechanism of sandstone under uniaxial load and established a mechanical damage model modified based on AE signals. Chai et al [9] used the DIC system to study the deformation characteristics of rock-like materials and divided the rock damage evolution process into four stages according to the redefined damage variables.…”

Mechanical Properties and Energy Dissipation of Sandstone under Cyclic Loading‐Unloading

“…As the most common load-bearing medium, rock widely exists in geotechnical engineering, such as mine surrounding rock tunnels and underground protection projects [1][2][3][4][5][6][7]. Affected by human excavation activities, rock masses are in varying degrees of damage under the disturbance of cyclic loads with different upper-stress limits [8][9][10].…”

Analysis of Energy Dissipation Characteristics of Damaged Sandstone under Impact Load

“…In the long period of geological history, the rock has experienced the geological tectonic movement, so that there are different degrees of joints, fissures, and other weak surfaces in the rock, and in different degrees of damage state [8][9][10][11][12]. In modern times, affected by the disturbance of rock burst [13], coal and gas outburst [14], and human excavation activities [15], the damaged rock mass began to destroy and lose stability under the action of dynamic load, which caused great hidden danger to the safety of engineering production and human life [16]. Due to the different stress history of the bearing rock mass, the damage caused by the weak surface is different, and the dynamic response of the rock with different damage degrees is also different [17].…”