Chapter 31 The use of bamboo and bakau piles for soil improvements and application of pile raft system for the construction of embankment on peats and soft soils

Abstract

Construction of embankment on peats and soft soils has always been faced by the problems of instability and large settlement. The conventional system conducted in practice by Indonesian engineers is the use of bamboo pile raft system (known as “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 water table, these materials are durable. In the past decade, mini concrete pile raft has emerged to replace bamboo pile raft to carry bigger load and overcome the limitation of bamboo or timber piles. Despite the more popular application of this system until present, no method of design and analysis has been established, and approach for calculation are 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, other timber or minipile raft system, method of installation of pile raft under embankment 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 full-scale investigation and case histories are used to illustrate the behaviour of single or grouped piles, to observe the suitability for certain soil condition and to gain an overview of its applicability. It has been proven that the system gives advantages to the increase of the bearing capacity of the soft foundation soils and reduce 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 or other timber piles and concrete pile raft system for geotechnical practice.