Exploring the Occurrence of Clogging in Highly Permeable Coarse Soils of Dam Foundations

Jianquan Ma,Shibo Li,Xinshe Zhang,Zhao Duan,Hao Peng,Donghe Ma

doi:10.1155/2020/8868052

Abstract

Leakage through the permeable coarse soils of dam foundations in Tibet, China, lessened over time without any additional antiseepage measures. In fact, clogging generated during the infiltration process is recognized as the major factor in reducing leakage. A laboratory study was conducted to understand clogging in highly permeable coarse soil of a dam foundation with the primary aim of determining the clogging patterns and optimum clogging particle size (PS). Seven replicate experiments were constructed using soil media with PS ranges of 32–64 mm, 16–32 mm, 8–16 mm, 4–8 mm, 2–4 mm, 1-2 mm, and 0.5–1 mm to observe clogging after feeding the soil media with sediments of different PSs. The experimental results showed that four clogging patterns were formed in different PSs of the coarse foundation soil. The ratio of the effective aperture of the soil Dea and the equivalent clogging particle size dede/Dea had a dominant effect on the four clogging patterns (surface clogging, de/Dea>1; surface-internal clogging, 0.5<de/Dea≤1; internal partial pore blockage, 0.25<de/Dea≤0.5; and unclogging, de/Dea≤0.25). The assessment criterion of the optimum clogging pattern was determined by 0.5<de/Dea≤1, and from that, the optimum clogging PS do was calculated.

Highlights

Leakage is a major safety issue that influences the economic value of dams and threatens dam stability [1,2,3,4]
It was reported that the sediments of the reservoir dam foundation in Shannan, located in the south of Tibet Province, China, were deep and overlain by coarse-grained soils originating from glacial deposits and characterized by physical weathering and high permeability [5, 6], creating a risk of leakage [7, 8]
A decades-long survey of five reservoirs (Daranduo Reservoir, Jiangxiong Reservoir, Jiaripu Reservoir, Qiongguo Reservoir, and Awoduo Reservoir, as shown in Figure 1(a)) in the Shannan area found that the state of leakage in the dam foundations at these sites lessened with time without any additional antiseepage measures [11,12,13]

Summary

Introduction

Leakage is a major safety issue that influences the economic value of dams and threatens dam stability [1,2,3,4]. E reason for this phenomenon was verified under seepage conditions in the dam foundation and was attributed to fine soil particles that were transported and retained in the pores, reducing leakage [6]. Erefore, placing fine sediments into foundation soil pores can serve as a recovery technology approach for leakage in foundation soil, similar to using geomembranes, as an effective method of clogging. By preventing the erosion of base soils and building up pore pressure, clogging provided an effective method to obtain internal stability [9, 15]. It is evident from research in porous media that physical

Methods

Results

Conclusion