ANALISIS KESTABILAN LERENG DALAM PENANGANAN TIMBUNAN PADA TANAH LUNAK STUDI KASUS JALAN TOL SEMARANG-SOLO STA 4+350 - 4+ 600

Abstract

To the number of development infrastructure is the determinant factor in national economics growth. One of the infrastructure that very important is development of highway as medium transportation that very useful to increase of economics country. In development of highway, the location wich will be developed sometimes have not according to relief with development planning, so that necessary to do cut and fill process. This process yielding new geometrical slope that need analysis simulation and calculation in stability of bevel so that to reach factor of safety value which determined. The research area located in Semarang-Solo higway STA 4+350 - 4+600. In this research, analysis simulation and calculation in stability of bevel use computing method which simulated by geostudio program. Factors having an effect on this simulation are geometrical slope and mechanical characteristic of material which consist of cohesion (c), weight unit (γ), and angle shift in (). In analysis and calculating, the stability of bevel is safety or stable if factor of safety value  1,4. Pursuant to calculation result indicating factor of safety value in early condition from bevel result of fill is 0.74. This value is not yet to reaching factor of safety value which is determined, so that necessary to improvement strength material at this bevel. The methods that used to improvement strength material are grouting and replacement of material. From the simulation result, the improvement strength material with grouting method is factor of safety value increase to be 1.602 at cohesion increase 20 kPa with expense Rp 498,750,000.00, while the improvement strength material with replacement of material is factor of safety value increase to be 1.613 with expense Rp 498,750,000.00. The result of the simulation and calculation in the improvement strength material with grouting and replacement of material method indicating that both of them can improve of strength material reaching stable condition. But that way if is seen from expense, grouting method is cheaper than replacement of material, so that this method more major to do it at this bevel result of fill.