Study on the shear deformation of intralayer shear bands at the Baihetan hydropower station dam foundation
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ORIGINAL PAPER
Study on the shear deformation of intralayer shear bands at the Baihetan hydropower station dam foundation Anchi Shi 1 & Yufeng Wei 2 & Jiayao Wu 1 & Dachun Ren 3 & Mingfa Tang 1 Received: 3 November 2019 / Accepted: 8 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The engineering geological environments of the Baihetan hydropower station dam site are complicated due to the existence of columnar jointed basalt with faults and intralayer shear band structures. In the excavation process of the left dam foundation, relaxation and deformation of the columnar jointed basalt and the unloading shear deformation of the intralayer shear bands are both important engineering geological problems. Taking a typical intralayer shear band exposed during the excavation of the left dam foundation of the Baihetan hydropower station as an example, the unloading shear deformation of the intralayer shear band was investigated by in situ testing and numerical analysis in this study. The results confirmed that the unloading shear deformation of the intralayer shear bands can present an instability risk for the left dam foundation due to their poor mechanical strength and shearing damage. Therefore, a reinforcement measure of intralayer shear bands is critical for the stability assessment of similar structures. Keywords Intralayer shear bands . Unloading shear deformation . Columnar jointed basalt . Faults . In situ testing . Numerical analysis . Dam foundation
Introduction In recent years, many large hydropower projects have been or are being constructed in Southwest China, e.g., Xiluodu,
* Yufeng Wei [email protected] Anchi Shi [email protected] Jiayao Wu [email protected] Dachun Ren [email protected] Mingfa Tang [email protected] 1
Powerchina Huadong Engineering Corporation Limited, Hangzhou, China
2
State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology), Chengdu University of Technology, Chengdu, China
3
China Three Gorges Projects Development Co. Ltd, Chengdu, China
Dagangshan, Baihetan, Shuangjiangkou, and Lianghekou (Li et al. 2018; Zhao et al. 2018a; He et al. 2019). During the construction process of the Baihetan hydropower station, many discontinuities, including cracks, joints, intralayer shear bands, and faults, were revealed in the left dam foundation, and such materials have a great impact on the deformability, strength, and stability of the left dam foundation due to their poor mechanical properties (Feng et al. 2016; Xiao et al. 2017; Fan et al. 2018; Jia et al. 2018). Thus, it is important to analyze the stability and deformation of rock masses containing specific geological structures (Zhang et al. 2016; Zhou et al. 2018). Based on previous investigations, many efforts have been made to assess the stability and deformation of rock slopes, including numerical simulations, in situ surveys and measurements, and physical model tests. For instance, Zhang et al. (2007) validated the Goodman-Bray method for roc
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