Organic soils consist predominantly of vegetative materials in various stages of decomposition or preservation. In Southeast Asia, most organic soils can be found near the ground surface overlying or embedded within soft clay deposits. These organic soils have not been as extensively studied as the soft clay and are classified under the general term of peaty soils. In construction where superficial layers of peaty soils are encountered, they are usually disposed and replaced with more competent soil materials. Areas where peaty soils occur in greater quantities are deemed unsuitable for construction and are generally avoided. The increase in population and economic activities in the Southeast Asian countries will, in time, make largescale disposal of peaty soils unacceptable resulting in a demand for adequate solutions to improve the engineering characteristics of these peaty soils. The objective of this paper is to present a review of the geotechnical characteristics of peaty soils in Southeast Asia. This general overview provides the current state of knowledge of the geotechnical characteristics of peaty soils in Southeast Asia and identifies future areas of improvement for studying their behaviour and treatment methods for engineering applications.
Peat as defined in ASTM D4427–92 (1997) is a naturally occurring, highly organic substance derived primarily from plant materials. Peat is distinguished from other organic soil materials by its lower ash content (less than 25% ash by dry weight) and from other phytogenic material of higher rank (i.e., lignite coal) by its lower calorific value on a water-saturated basis. The rate of peat accumulation varies from place to place and peat accumulation continues as long as bog plants can live and die at the surface. The drainage and harvesting of peat terminates the process. The location of peat swamps in Southeast Asia is shown in Figure 1.
