Analysis of Soil Behavior in the Trial Embankment Zone N Using Geotechnical Instruments on the Semarang - Demak 1B Toll Road Work (STA: 4+200–4+600)

Juny Andry Sulistyo, Zidan Rifqi R.

Abstract

The soil condition in the trial embankment of the Semarang-Demak 1B toll road project consists of a soft soil layer that tends to be very compressible, has low shear resistance, low permeability, and low carrying capacity. Therefore, soil improvement methods such as preloading and PVD installation are needed to accelerate the soil consolidation process. This study aims to evaluate the subsidence and stability of the groundsoil due to the load of the experimental stockpile. The research method was carried out by installing several geotechnical instruments, namely settlement plates, piezometers, and inclinometers to monitor soil response to the load of the heap. Observation data were analyzed to assess the magnitude of the decrease, pore pressure dissipation, and lateral movement of the soil. The results of the analysis show that the actual decline in the field is close to the predicted result of the calculation, with the degree of consolidation at most points having exceeded 90%. The lateral movement of the soil recorded by the inclinometer is still above the set tolerance limit of 375 mm. This indicates that the stack should require further evaluation, the average degree of consolidation reaching about 90.74%, which indicates that most of the excess pore pressure has been dissipated. The preloading and PVD methods have proven to be effective in speeding up the consolidation process.