Solutions for Underground Drainage and Stability of High Embankment Slope at Nhan Co. Industrial Zone, Dak Nong, Vietnam

The article mentions a case in situ on slope stability solutions with 60 m high for the infrastructure of Nhan Co Industrial Zone, Dak Nong, Vietnam. The embankment is finished in February 2020, obstructing the troughed tributary streams of about 14 ha. The retaining wall at 6–8 m high and the embankment has 5 benches with grade of side slope m = 1:1.50 for each one. The first bench is adjacent to the top filled by closed cement concrete slabs, whereas the other times using the open ones; the materials are mainly K90 well-compacted basalt in place. On April 4th, 2020, there is a 150 m-in-length, 70 m-in-width and 40 m-in-height landslide [1]. The pit crest has a 15-meter subsidence. The landslide is moved out of the embankment slope covering the wall. The expected movement is about 10–15 m long. The survey data is made right after the landslide showed that the physical properties of the embankment have changed, especially the groundwater level rises [2]. The groundwater flowing into the site is about 2.6 m³/day/m of the retaining wall. The analysis results show that the safety factor (SF) of the embankment is stable with SF = 1.0564 and it is unstable when the groundwater level rises in rainy seasons with SF = 0.8420. We have proposed the solutions for underground drainage and slope stability of the project to put into use and operation.