Experimental Investigation on Geomechanical Properties of Tropical Organic Soils and Peat

Abstract

Problem statement: Organic soils and peat were believed to be geotechnically problematic due to their very high compressibility, very low shear strength and difficult accessibility. Although conventional soil mechanics theory could be applied to the soils, it was found that important anomalies existed which required special considerations. Correlations between geomechanical parameters for the soils were known to be important for geotechnical engineers to be able to obtain suitable design parameters, as well as to find suitable construction techniques on these soft materials. Approach: To evaluate the geomechanical characteristics of the soils, field and laboratory investigations were carried out according to the organic contents. To achieve such purpose, the soils samples having different organic contents from several locations in Malaysia were collected to determine the correlations of various geomechanical properties of the soils. The classifying tests were determined based on the test procedures according to the British Standard Institution. The compressibility behavior of the soils was determined by Rowe cell consolidation test. Results: The test results indicated that the natural water contents, organic contents, liquid limits, specific gravities and bulk densities ranged from 150-700%, 50-95%, 180-500%, 1.05-1.9 and 0.8-1.2 Mgm −3 , respectively. The compression indexes of the soils were higher than Hobbs and Skempton's approximations. Conclusion/Recommendations: The soils properties were highly dependent on the organic contents. With an increase in organic content, the natural water content, liquid limit, compression index and void ratio increased and the specific gravity and bulk density decreased. Furthermore, the hemic and sapric peat had lower shear strength than the fibrous peat. The first-of-its-kind study was the first step on the road to persuade researchers to improve these problematic soils.

Effect of fibre content on the geotechnical properties of peat

“…It can be seen in Figure 3 that the organic content increased with the increase in the natural water content. However, the tested peat was characterised by a lower variability of organic content depending on the natural water content than the results obtained from Equation (1) (Huat et al, 2009). An empirical correlation between the organic and water contents of the tested peat was established (Fig.…”

“…The temperature of 550 o C causes combustion of organic matter to ash (Heiri et al, 2001). When the natural water content of peat w n is known, the organic content I om can be predicted using the equation given below (Huat et al, 2009):…”

“…One of the types of organic soils with the highest organic content is peat, which is the objective of research for civil engineers, geologists, geotechnical engineers, botanists, soil scientists and farmers. Peat is an organic material (less than 25% by weight of mineral matter) composed of partially or totally decomposed plant remains, which have accumulated under watersaturated conditions (Huat et al, 2009;Rezanezhad et al, 2016;Skreczko et al, 2021;Zaccone et al, 2007). It has a spongy consistency, a distinctive organic odour and is brown to black in colour (Craig, 1992;Huat et al, 2011bHuat et al, , 2014.…”

Evaluation of the Organic Soil Compressibility from In-Situ and Laboratory Tests for Road Application

“…One of the organic soil types is peat. Peat is known as partially decomposed plant remains which have accumulated under water conditions for ten to thousands of years (Huat et al, 2009). It has distinctive organic odour and brown to black colour (Huat et al, 2014).…”

River Embankment and Bank Failure: A Study on Geotechnical Characteristics and Stability Analysis

“…However, clear understanding of material behavior is necessary to interpret the failure phenomenon of a particular problem. To acquire appropriate understanding, some researchers already tried to characterize geotechnical properties of soil facing mass failure problem like landslides or containing organic matters (Ahmad et al, 2006;Huat et al, 2009). In this study, embankment failure and riverbank erosion problems in Bangladesh have been looked with respect to the factors regarding stability and geotechnical characteristics.…”