Safety evaluation with observational data and numerical analysis of Langyashan reinforced concrete face rockfill dam

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CASE HISTORY

Safety evaluation with observational data and numerical analysis of Langyashan reinforced concrete face rockfill dam Xiangnan Qin 1,2,3

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Chongshi Gu 1,2,3

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Chenfei Shao 1,2,3 & Yue Chen 1,2,3 & Luis Vallejo 4

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Erfeng Zhao 1,2,3

Received: 30 October 2019 / Accepted: 26 March 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Deformation characteristics of rockfill and stress condition of slabs play important roles in the safety of concrete face rockfill dam (CFRD). In this study, an analysis based on monitored data and numerical simulation is conducted to evaluate the performance condition of Langyashan CFRD, which is built on a wide valley and has a mansard dam axis. The observational rockfill settlement is analyzed firstly, then a numerical model is established in accordance with the practical engineering. The numerical results of the rockfill settlement exhibit favorable consistency with similar projects or measured data in both construction and operation stages. Furthermore, the deflections and stress states of the face slabs are analyzed, and the effect of rockfill deformation and temperature variations are recognized as the main influence factors. The potential area of the face slabs vulnerable to cracks is predicted based on the stress state. The numerical results provide a reference for safety monitoring and inspection in the future operation. Keywords Concrete face rockfill dam (CFRD) . Numerical simulation . Rockfill settlement . Slabs stress . Fracture prediction

Introduction Concrete face rockfill dam (CFRD) was developed rapidly after the late 1970s in China, and a large number of CFRDs have been built successively, including Xibeikou CFRD (95 m height), Tianshengqiao-I CFRD (178 m height), Hongjiadu CFRD (179.5 m height), and Shuibuya CFRD (233 m height), the highest built CFRD in the world. CFRDs are extensively constructed due to its strong topographic adaptability, economical engineering plan, and simple construction technology. As the major components of CFRDs,

* Chongshi Gu [email protected] 1

College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China

2

State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China

3

National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Hohai University, Nanjing 210098, China

4

Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA

the deformation characteristics of rockfill and stress condition of slabs are significant to the safe operation of the whole project. The deformation of rockfill consists of instantaneous and creep deformation, and long-term creep deformation in CFRDs may easily result in catastrophes considering its close relations with the concrete slabs (Sherard and Cooke 1987; Clements 1984). At present, many scholars have conducted significative researches on the settlement behavior of rockfill materials in