Chapter 24 - Use of Bamboo and Bakau Piles for Soil Improvement and Application of a Pile–Raft System for Embankment Construction on Peat and Soft Soils

Abstract

Construction of embankments on peats and soft soils has been problematic due to instability and large settlement. The conventional system conducted in practice by Indonesian engineers is the use of a bamboo pile–raft system (i.e., a cerucuk), owing to its availability and low cost. Another aspect to be considered is simple technology. Bakau piles, ulin, and gelam timber are also used as alternatives to bamboo piles. When used under the water table, these materials are durable. In the 1990s and early 2000s, a mini-concrete pile–raft system emerged to replace bamboo pile rafts enabling higher loads and overcoming certain limitations of bamboo and/or timber piles. Despite the more popular application of this system, no real method of design or analysis was established, and calculations were generally based on experience or simplification. This chapter contains general information on the occurrence and characteristics of soft soils in Indonesia; ideas and principles on the use of bamboo and other timber or minipile–raft systems; methods of installation of pile rafts under embankment and over soft soils and peats; examples of the use of the system in a number of projects in Indonesia; and proposed methods of calculation. Results of a full-scale investigation and case histories are used to illustrate the behavior of single or grouped piles, to observe the suitability for certain soil conditions, and to gain an overview of applicability. It has been proven that the system provides advantages, including increasing the bearing capacity of the soft foundation soils and reducing the settlement of the embankment. The system has been successfully applied in many projects and should be further investigated. In summary, this chapter gives insight and overview of the use of bamboo and other timber piles and the concrete pile–raft system for geotechnical practice.