Kediri airport is the first privately developed airport in Indonesia. Situated 150 kilometres south-west of Surabaya, the airfield and associated buildings cover a vast area of 330 hectares.
The airport is being built to provide improve connectivity and boost the economy of the southern part of the East Java province, as well as to supplement the operation of Juanda International Airport. Davy Sukamta & Partners was appointed as the earthwork consultant for this project.
Design and construction of the earthwork for the platform are considered complex. It consists of intricate cut and fill work up to 30 meters high on the slope of Mount Willis, which requires the use of various ground improvement techniques.
Some ground improvement works at certain areas are required to overcome the settlement. Settlement analysis is evaluated using finite element analysis performed using Plaxis 2D software. The work of Stone Column (SC) and Down-hole Dynamic Compaction (DDC) with a total of approximately 41,412 piles have been completed.
Most of the platform above the runway has high fill embankment and requires a Ground Improvement to mitigate consolidation settlement.
The design criteria for the maximum settlement due to embankment on the runway are 20mm/1 year and 100mm/10 years and differential settlement must meet the criteria for serviceability of 30mm/45m or 1:1500 based on the International Civil Aviation Organization.
For the 23-meter-high fill embankment, the existing soil has been improved using the stone column (SC) method to mitigate consolidation settlement.
Two rivers namely Hardisingat and Kolokoso cross the runway platform. They are diverted through open channels and RC box culverts. By mid-July 2022 the rivers have been diverted, and the fill work in the former riverbed can be executed. Moreover, all the structures for the river diversion have been completed. The fill above the box culverts ranges from 17 – 24 meters high on the Charlie culvert.
On the Eastern side of the Dhoho Kediri airport platform, a high slope must be constructed due to the limitation of the acquired land for the project. The highest part reaches 26 meters high. To answer this challenge, we use MSEW retaining wall. MSEW retaining wall is a composite structure consisting of alternating layers of compacted backfill and geosynthetic grids as soil reinforcement elements.
The stability of the wall system is derived from the interaction between the backfill and soil reinforcements, involving friction and tension. The MSEW must be designed for static and seismic conditions.
Two huge Reinforced Concrete box culverts, buried underneath the Dhoho Kediri airport runway embankment, will serve as the main infrastructure facilitating diversion of two main crossing rivers. The soil embankment height above the box culverts ranges up to 24 meters above the box culverts.
Davy Sukamta & Partners was also requested to conduct value engineering services to evaluate, modify, and optimize the design of the box culverts. The box culverts were originally designed by a world-class engineering consultant. With our value engineering, we were able to provide an alternative design solution, providing a substantial value to the project. This has resulted in massive amount of cost savings.