# Stability Improvement Method for Embankment Dam with Respect to Conduit Cracks
## 4 Conclusions  
In this study, a large-scale model test and three-dimensional deformation-seepage analysis were performed to understand the effect of internal erosion due to conduit cracking on the stability of the embankment dam in the current design model. In addition, the reinforcement effect of the proposed improvement model, which aimed to reduce internal erosion, was evaluated, and its validity was discussed.  
Under the cracking condition in a conduit, the current design method for conduits was evaluated as having a high risk of embankment failure due to the occurrence of cavitation with erosion near the cracked area. In the improvement model, which applies a layer of sand and geotextile, although erosion occurred, cavitation did not appear near the conduit. These results are related to the effect of the drainage layer dispersing the water pressure in the improvement model, indicating that the erosion velocity can be suppressed.  
In the current model, as a result of reinforcing the cracked area of the conduit with a geomembrane, a wide saturation area in a loose state was observed on the downstream slope. Saturated areas on slopes near the conduit can increase the risk of disasters due to increased internal erosion in case of an emergency. The improvement model proposed in this study is expected to provide the embankment with additional stability compared to the current model because the saturation area of the downstream slope is greatly reduced.  
The pore water pressure, hydraulic gradient, and seepage line investigated in this study are valid data that can support the results of internal erosion in this model experi  
Figure 10: Time histories of variations in hydraulic gradients under (**a**) crack and (**b**) reinforcement conditions.  
ment. These data explain the relationship between conduit cracks and the stability of the embankment and can be used as fundamental data for the reduction in internal erosion.  
Despite the small crack scale of the conduit, piping may occur due to internal erosion under low water level conditions. The improvement model proposed in this study is a useful method that can improve the safety of the embankment compared to the current method because it can suppress the development of cavitation and piping, even if structural defects, such as cracks, occur in the conduit.  
Software, J.-H.R.; investigation, J.H. and J.-W.S.; writing--review and editing, Y.-H.L.; project administration, supervision, and conceptualization, D.-W.L. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (grant no. 2019R11A3A01058517), and the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science, ICT & Future Planning of the South Korean Government (grant no. 2019R1C1C1007100). In addition, this work was supported by the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry (IPET) through the Agricultural Infrastructure and Disaster Response Technology Development Project, funded by the Ministry of Agriculture, Food and Rural Affairs (MAFRA) (grant no. 320002-01).  
Not applicable.  
The study did not report any data.  
We would like to thank the Rural Research Institute and Korea Rural Community Corporation for their support (data and administrative) to prevent disasters caused by cracks in conduits.  
The authors declare no conflict of interest.