Deterioration Analysis and Consolidation Time Using Terzaghi 1-D Method and 3D Plaxis Modeling: A Case Study of the Tebing Tinggi Toll Road Development Project - Indrapura STA. 103 + 200

Abstract

Land transportation has an important role in the transportation sector. Road infrastructure is growing rapidly to meet basic human needs which increasingly require rapid movement for distribution of basic needs and other logistics. Soil has the characteristics of a relatively low bearing capacity and relatively large compression and lasts a relatively long time. One of the factors that cause soft soil to have a low bearing capacity is having a high water content. The high level of compressibility in soft soils is caused by the high void ratio. The development of preloading and vertical drainage methods is also combined with the use of horizontal drainage. Preloading works to compress the subgrade. PVD (Prefebricate Vertical Drain) serves to accelerate the process of soil compaction. PHD (Prefebricate Horizontal Drain) works to drain pore water from the PVD in a horizontal direction to the outside of the embankment. Located on the Tebing Tinggi Toll Road Construction Project – Kisaran (Phase 1), the Tebing Tinggi Inderapura Toll Road in zone 3 Sta 103 +200. The purpose of writing this thesis is to analyze the magnitude of the settlement and consolidation time using analytical methods and using modelling in PLAXIS 3D. Analyzing the effect of the smear zone due to PVD erection using a mandrel. Analyzing the effectiveness of using PHD as horizontal drainage. Knowing the pore water pressure that occurs. Comparing the results of PLAXIS 3D modelling with data settlement in the field. The calculation of the consolidation settlement using the 1-dimensional Terzaghi method was obtained at 102,46 mm. This result is relatively close to the conditions that occur in the field, where the decrease in the SP-132 settlement plate in the field is 103 mm and the decrease in Asaoka is 102 mm. The consolidation time required when there is a decrease of 100 mm in PLAXIS 3D modelling with a smear zone effect is 243 days and without a smear, the zone effect is 240 days. The required consolidation time without the use of PHD is 242 days and the consolidation time from the data settlement plate 132 (SP-132) is 239 days. Calculation of settlement and consolidation time using PLAXIS 3D modelling by taking into account the effect of the smear zone gives results that are close to the situation in the field. From the results of the PLAXIS 3D modelling, it is found that the minimum pore water pressure occurs until the end of the stockpiling activity for 248 days. The use of PVD in combination with PHD is effectively applied in the field, indicated by the minimum pore water pressure that occurs is smaller than without using PHD. From the percentage of pore water pressure that occurs in the soil, 64,4% is greater by using PHD, meaning that the percentage of water that comes out is faster by using PHD. Keywords: Preloading, PVD, PHD, consolidation, PLAXIS 3D.