It is important for us to know the slope safety number, in order to create a safe and comfortable road. In unstable slope conditions, reinforcement is needed, one form of reinforcement is by making talud on the slope.
This study aims to determine the safety factor of the slope, before and after being given reinforcement in the form of retaining wall. Analysis of the calculation of the safety factor is done manually, namely the fellenius method and with the geostudio application.
The results of the study obtained that the slope safety rate by manual calculation was SF = 1.44, with the geostudio application it was SF = 1.195. After being given retaining wall reinforcement with variation I (retaining wall height 3.8m, pedestal width 1.9) obtained (Fgs = 3.11, Fgl = 2.67, SF soil bearing capacity = 9.20), variation II (retaining wall height 3.7m, pedestal width 1.85m) obtained (Fgs = 3.10, Fgl = 2.69, SF of soil bearing capacity = 9.24), Variation III (with retaining wall height 3.6m and 1.8m pedestal width) was obtained (Fgs = 3.10, Fgl = 2.72, SF soil bearing capacity = 9.28). For slope safety figures after being given retaining wall reinforcement, variation I obtained SF = 2.111, variation II SF value = 2.061, and variation III SF value = 2.013. The retaining wall with dimension variation III is considered efficient, because it has smaller dimensions than the other 2 variations, so that it can save budget costs in its manufacture.