Mechanical Properties and Acoustic Emission Characteristics of the Bedrock of a Hydropower Station under Cyclic Triaxial
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ORIGINAL PAPER
Mechanical Properties and Acoustic Emission Characteristics of the Bedrock of a Hydropower Station under Cyclic Triaxial Loading Xiang‑Yi Zhu1 · Xu‑Dong Chen2 · Feng Dai3 Received: 5 October 2019 / Accepted: 25 July 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The bedrock of hydropower stations is susceptible to irreversible failure due to dynamic unloading and loading related to earthquakes, rock bursts or blasting. To ensure operational safety, the damage evolution process of bedrock under cyclic loading must be investigated. Hence, this study investigates the mechanical properties and acoustic emission (AE) characteristics of the bedrock from different positions of the Badantoru hydropower station under different confining pressures. First, the relationship between the dynamic elastic modulus and residual strain is analyzed, and then the brittleness and damage of the rocks are quantitatively characterized. Subsequently, the failure process and crack development of the rocks are revealed from the obtained AE characteristics. The results show that as the applied confining pressure increases, the peak differential stress and fatigue life of the rock specimens increase; whereas, the shear failure angle decreases. Under the same confining pressure, the rocks with a greater number of internal joints and pores (Dam Site I) have a lower bearing capacity under cyclic loading, a greater brittleness after strain softening, and a smaller shear failure angle. With increasing plastic strain, all of the specimens exhibit cyclic softening, and an obvious four-stage fatigue damage evolution can be observed. Keywords Cyclic triaxial loading · AE characteristics · Saturated tuff · Dynamic elastic modulus
1 Introduction The mechanical properties of rocks play an important role in ensuring the stability of rock mass engineering, such as underground tunnels, dam foundations and bridge abutments. In dam foundation engineering, bedrock is susceptible to irreversible damage or even instability due to cyclic loads resulting from earthquakes, rock bursts or blasting (Liu et al. 2017a, b; Liu and Dai 2018; Wang et al. 2019b). Thus, it is important to investigate the mechanical properties and damage evolution process of bedrock under cyclic loading to analyze the long-term stability of dam foundations. * Feng Dai [email protected] 1
College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, Jiangsu, China
2
College of Civil and Transportation Engineering, Hohai University, Nanjing 210098, Jiangsu, China
3
State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resources and Hydropower, Sichuan University, Chengdu 610065, Sichuan, China
Scholars have studied the damage and failure process of different types of rocks under cyclic loading. However, most previous research has focused on the mechanical properties of rocks under cyclic uniaxial loading (Li et al. 2001; Bagde and Petroš 2005a, 2009; Xiao et al. 2010). These
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