Slope stability is an important aspect in excavation work, especially in road construction projects that affect construction safety. In the construction project of Jalan Bululawang-Sidomulyo-Tambakrejo, STA 14+675, there was a landslide on the excavation slope with an initial geometry of 4V:1H and a height of about 10 meters. This study aims to identify the factors that cause landslides and evaluate effective treatment alternatives. The research method uses a quantitative descriptive approach supported by finite element method (FEM) based numerical analysis through PLAXIS 3D software. The soil characteristics were obtained from drill data, soil laboratory tests, and geoelectric surveys and then compiled into a stratigraphic model for modeling. The results of the analysis showed that the increase in groundwater level had a significant effect on the reduction of slope safety factors due to increased pore pressure and decrease in effective voltage. The existing condition has a safety factor of 1.498 and reaches unstable conditions when the groundwater level rises to an elevation of +20.5 meters with an SF value of 0.980. From the results of the modeling variation, the regrading with a slope ratio of 1V:1H indicates the most stable slope condition (SF>1.5). Evaluation of slope handling by regrading the first trap to 1V:1H and maintaining a steep slope in the second trap 4V:1H offered the best handling in terms of unit price of Rp. 35,685,000.00 m3/m with a SF value of 1,512. However, the first and second trap regrading with a ratio of 1V:1H gave a higher SF value of 1.782 but required 15% more land than the previous modeling variation The most stable slope handling conditions with the second 1V:1H trap regrading with the addition of a soil retaining wall structure obtained an SF value of 2.053 with the highest unit price implication of Rp 52,576,000.00 m3/m.
Mahfud et al. (Fri,) studied this question.