When it is necessary to expand or build an existing road or railroad by stacking soil on the slope of the base ground, soft ground often exists in the lower area when it is adjacent to a river or rice field. Even if the base ground is inclined, the slope of the soil should be built within the standard slope according to the regulations, and the stability of the slope bottom destruction due to the weight of the soil on the base ground should be reviewed for adjacent soft ground. At this time, if it is judged to be unstable, the slope or height of the slope of the base ground soil should be adjusted, or a separate countermeasure method should be established for the adjacent soft ground. Recently, when applying the soft ground countermeasure method, environmental problems have emerged as well as economic feasibility and construction performance.

In this study, the embankment method was used to reinforce the slope of the embankment slope in the waste landfill. The waste landfill has a water cutoff film installed at the bottom of the landfill for the purpose of preventing leachate due to environmental concerns, so reinforcement methods should be sought in a way that does not damage it.

In the case of the pressurized earth method, it is widely used as a representative reinforcement method for soft ground embankment slopes, and when applying the pressurized earth method, it was intended to confirm the seismic stability of the ground. In the revised seismic design standard notice of the waste landfill ground (Ministry of Environment, 2019), a stability analysis should be conducted by reflecting the one-dimensional ground response analysis and the revised seismic design standards. Therefore, the reinforcement effect was verified through laboratory experiments and numerical analysis by applying the seismic force that met the corresponding criteria.

As a result of PGA (Peak Ground Acceleration) analysis using a 1g shaking table test, the PGA amplification rate from the bottom to the top before reinforcement amplified 27.74% in the first row, 33.76% in the second row, and 36.23% in the third row. When reinforcing 10m thick soil, the amplification rate in the first row decreased to 27.74%, the second row to 32.96%, and the third row to 27.21%. When reinforcing 15m thick soil, the amplification rate was 22.91% in the first row, 31.07% in the second row, and 19.06% in the third row. These results showed that the amplification rate of seismic waves was lower when reinforcing 10m and 15m, and in particular, when reinforcing 15m, the amplification of seismic waves was further reduced than when reinforcing 10m. This is judged to improve the safety of ground structures by reducing seismic wave amplification more effectively using reinforcement using embankment materials.

As a result of the numerical analysis and verification of the reinforcement of the crushed earth of the landfill site 3, it was confirmed that both the standard safety factor exceeded when reinforcing the crushed earth 10m and 15m. It was confirmed that the safety rate of the slope after reinforcement exceeded 1.46 to 2.64 during the dry season and 0.77 to 1.35 during the earthquake, and there was no significant difference from the reinforcement of 10m of pressure soil. Likewise, it can be confirmed that the destruction area against deep destruction of the soft ground under the slope has been eased when applying pressure soil.