JRMGE / Vol 14 / Issue 3

Article

Model-scale tests to examine water pressures acting on potentially buoyant underground structures in clay strata

Zhisheng Ren, Qixian Lu, Kaiwen Liu, Pengpeng Ni, Guoxiong Mei

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a School of Civil Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Key Laboratory of Oceanic Civil Engineering,
Guangdong Research Center for Underground Space Exploitation Technology, Sun Yat-sen University, Guangzhou, 510275, China
b Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, College of Civil Engineering and Architecture, Guangxi University, Nanning,
530004, China
c State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, 430072, China
d Key Laboratory of High-speed Railway Engineering (MOE), School of Civil Engineering, Southwest Jiaotong University, Chengdu, 610031, China


2022, 14(3): 861-872. doi:10.1016/j.jrmge.2021.09.014


Received: 2021-07-22 / Revised: 2021-08-24 / Accepted: 2021-09-09 / Available online: 2021-11-27

2022, 14(3): 861-872.

doi:10.1016/j.jrmge.2021.09.014


Received: 2021-07-22

Revised: 2021-08-24

Accepted: 2021-09-09

Available online: 2021-11-27


Abstract:

Throughout the service life, underground structures are subjected to transient and sustained hydrostatic pressures. The reservoir impoundment results in an increase in water level, as well as hydraulic gradient, which can endanger the uplift performance of infrastructure. In uplift design, a reduction factor is often suggested for buoyant force acting on underground structures in clays due to the time lag effect. However, the mechanism of pore pressure generation in clays is not fully understood. This investigation presents a novel U-shaped test chamber to assess the pore pressure generation with time in the horizontal branch subjected to an increase in reservoir level in the left vertical branch. A mathematical model is developed to explain the time lag effect of pore pressure generation. The test program also involves the evaluation of uplift pressure acting on foundation model in the right vertical branch due to adjacent reservoir impoundment. It is found that the time lag effect of pore pressure generation in clays can be observed irrespective of hydraulic gradient, but a higher hydraulic gradient can lead to a faster response in pore pressure sensors. A reduction factor of 0.84–0.87 should be considered to reduce the conservatism of uplift design.

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Keywords: Buoyant force, Reservoir impoundment, Pore pressure generation, Reduction factor, Uplift pressure, Time lag effect

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Zhisheng Ren, Qixian Lu, Kaiwen Liu, Pengpeng Ni, Guoxiong Mei, 2022. Model-scale tests to examine water pressures acting on potentially buoyant underground structures in clay strata. J. Rock Mech. Geotech. Eng. 14 (3), 861-872.

Author(s) Information

Pengpeng Ni

✉️ nipengpeng@mail.sysu.edu.cn

Pengpeng Ni obtained his BEng degree in Civil Engineering from Northeastern University, China, in 2010, his MSc degree in Earthquake Engineering from Université Joseph Fourier – Grenoble 1, France, and Istituto Universitario di Studi Superiori di Pavia, Italy, through the Erasmus Mundus Master’s Programme in 2012, and his PhD degree in Geotechncial Engineering from Queen’s University, Canada, in 2016. He worked at Nanyang Technological University, Singapore, as a Research Fellow from 2017 to 2019. He returned to China in 2019, and now is a Professor and Director for Underground Space Engineering at Sun Yat-sen University. He has co-authored over 100 publications, and received the Tso Kung Hsieh Award from the Institution of Civil Engineers, UK (Best Paper on Structural and Soil Vibration in Géotechnique). He serves as an Associate Editor for International Journal of Geotechnical Engineering since 2020. His research interests include soil-structure interaction, pipeline and trenchless technology, tunnelling, and foundation engineering, etc.