Analisis pengaruh SAND REPLACEMENT sebagai COUNTER WEIGHT pada proses konsolidasi di Reklamasi Belawan

Abstract

The problems most often encountered in constructions built on soft soil are soil settlement, soil movement and soil displacement. Soil improvement by preloading and PVD on large soft soils has a side effect, where the load received by soft soil does not quickly release soil pore water. Due to the nature of soft soil which has low permeability and shear angle, the soil will move sideways apart from downward, this causes the soil around preloading to be uplifted. The vertical displacement of soil layer will cause damage to existing buildings around the construction. In this project, a sand replacement is carried out at a location adjacent to other constructions as a counter weight to prevent the subgrade from being uplifted. This analysis aims to determine the amount of consolidation reduction using analytical methods and finite element methods with modeling on 2D and 3D Plaxis, the effect of installing sand replacement in the sand key area on the failure behavior of the embankment structure in reclamation area and smear zone effect on consolidation decline using Plaxis 2D and 3D Model on Belawan Phase 1 reclamation project. Calculation method used in this Thesis is the analytical method using Terzaghi theory and the finite element method using 2D and 3D Plaxis. From the analysis, it is found that the using sand replacement as a counter weight is able to prevent the uplifting of the soil layer in the shipping channel and to prevent construction failure in the preloading. Other results show that rate of settlement used the analytical results is 3.382 meters, while in Plaxis 2D it is 6.404 meters and from Plaxis 3D analysis is 6.356 meters. The settlement that occurred according to settlement plate observations in the field was 6,320 meters. So it can be concluded that the calculation of consolidation settlement using analytical theory is relatively close to the settlement in actual results in the field with a percentage difference of settlement is 1.611%. The decrease in consolidation with Plaxis 3D gives a result that is closer to the settlement in field observation than Plaxis 2D. Plaxis 3D results are more accurate than 2D Plaxis calculation results, where the percentage difference of reduction with three dimensions is only 0.566% compared to the results of field observations while two dimensions are 2.379%. Using sand replacement can prevent collapse of the embankment structure and prevent the uplifting of the subgrade in the shipping channel. Sand replacement be able to balance lateral ground pressure so that the surface of the shipping channel does not uplift. Preloading construction without using a counter weight on soft soil will collapse due to lateral deformation of the preloading load. The effect of the smear zone on soil subsidence is different for each type of soil, where in this study the values of s' = 3 and k = 4 have results that are closer to the results of field observations.

The problems most often encountered in constructions built on soft soil are soil settlement, soil movement and soil displacement. Soil improvement by preloading and PVD on large soft soils has a side effect, where the load received by soft soil does not quickly release soil pore water. Due to the nature of soft soil which has low permeability and shear angle, the soil will move sideways apart from downward, this causes the soil around preloading to be uplifted. The vertical displacement of soil layer will cause damage to existing buildings around the construction. In this project, a sand replacement is carried out at a location adjacent to other constructions as a counter weight to prevent the subgrade from being uplifted. This analysis aims to determine the amount of consolidation reduction using analytical methods and finite element methods with modeling on 2D and 3D Plaxis, the effect of installing sand replacement in the sand key area on the failure behavior of the embankment structure in reclamation area and smear zone effect on consolidation decline using Plaxis 2D and 3D Model on Belawan Phase 1 reclamation project. Calculation method used in this Thesis is the analytical method using Terzaghi theory and the finite element method using 2D and 3D Plaxis. From the analysis, it is found that the using sand replacement as a counter weight is able to prevent the uplifting of the soil layer in the shipping channel and to prevent construction failure in the preloading. Other results show that rate of settlement used the analytical results is 3.382 meters, while in Plaxis 2D it is 6.404 meters and from Plaxis 3D analysis is 6.356 meters. The settlement that occurred according to settlement plate observations in the field was 6,320 meters. So it can be concluded that the calculation of consolidation settlement using analytical theory is relatively close to the settlement in actual results in the field with a percentage difference of settlement is 1.611%. The decrease in consolidation with Plaxis 3D gives a result that is closer to the settlement in field observation than Plaxis 2D. Plaxis 3D results are more accurate than 2D Plaxis calculation results, where the percentage difference of reduction with three dimensions is only 0.566% compared to the results of field observations while two dimensions are 2.379%. Using sand replacement can prevent collapse of the embankment structure and prevent the uplifting of the subgrade in the shipping channel. Sand replacement be able to balance lateral ground pressure so that the surface of the shipping channel does not uplift. Preloading construction without using a counter weight on soft soil will collapse due to lateral deformation of the preloading load. The effect of the smear zone on soil subsidence is different for each type of soil, where in this study the values of s' = 3 and k = 4 have results that are closer to the results of field observations.