Compressibility Characteristics of Fibrous Tropical Peat ... - Ejge.com

More documents

Recommendations

Info

Vol. 14, Bund. C 6 Testing programs The samples were from marine and continental deposits of the Kampung Jawa Klang, Selangor, west coast of the Malaysian peninsula. They consisted primarily of fibrous organic soils and some fine-to-medium sands and were dark brown in color. As mentioned earlier, this study prepared the samples in accordance with BS 1377-1 (1990). We determined such physical properties of natural soil used in the tests as organic content, water content, liquid limit, and specific gravity in accordance with BS 1377-3(4) (1990), BS 1377-2(3) (1990), BS 1377-2(4.3) (1990), and BS 1377-2(8.4) (1990), respectively. We determined the organic matter (content) of the peat samples based on test procedures according to ASTM D 2974-87, and used the Von Post scale to find the degree of humification (Huat, 2004). Sample was then tested using Rowe Cell to overcome most of the disadvantages of the conventional oedometer apparatus when performing consolidation tests on low permeability soils, including non uniform deposits. The most important features are the ability to control drainage and to measure pore water pressure during the course of consolidation tests (Duraisamy et al., 2007-a, 2007-b). Figure 5: Rowe Cell Consolidation test set up used in this study. The system was comprised of a Rowe Cell Consolidation, gradually diverging system (GDS) pressure and volume controllers (Figure 5), and GDS laboratory software. The hydraulic loading system pressure and vertical loads (50, 100, 200 and 300kPa) can be applied to the sample surface either via a flexible diaphragm to give a uniformly distributed pressure (free strain) or via a rigid plate to give uniform settlement (equal strain). The bottom drain is provided with a tapping to a pressure transducer. This study performed the consolidation tests on low permeability soils on the peat based on BS 1377-6 1990 and determined the compressibility parameters of the samples without having to remove them from their sampling tubes. The samples therefore didn’t suffer disturbance due to their preparation, and the moisture content of the soils at the respective test horizons could be reported. The compressibility parameters in soils which were tested to assess the effect of the cement column with different cement ratio, to the consolidation parameters of the peat in this study are: 1. Coefficient of consolidation (C v ) 2. Compression index (C c ) 3. Coefficient of secondary compression (C α ), and 4. Coefficient of volume compressibility (m v ).
Vol. 14, Bund. C 7 RESULTS AND DISCUSSION Physical characteristics of Untreated (Natural) Peat This study performed the basic tests on natural fibrous tropical peat soil. Table 2, with some characteristics and indications of the concentration at which all of the studied organic compound are usually found in soils. It obtained a range of values almost in line with such other researchers as Ajlouni (2000), Huat (2004), Duraisamy et al. (2007-a) and (2007-b), Alwi (2007), Kazemian et al. (2009), Kalantari and Huat (2009). Table 2: Physical characteristics of the tested soil (untreated peat) Coefficient of consolidation (C v ) There is a significance decrease in the coefficient of consolidation of the undisturbed samples with an increase in effective stress above the apparent pre-consolidation pressure (σ c ) (Huat, 2004). Farrell et al. (1994) reported this decrease is more marked in the samples, which had the higher organic contents. The coefficient of consolidation for a particular pressure from consolidation test can be determined by curve fitting methods by using two methods: 1. The logarithmic time (Cassagrande’s) method; and 2. The square root time (Taylor’s) method. For fibrous peat, the results indicate that the coefficient of consolidation (C v ) decreased by increasing the load (consolidation pressure) and cement ratio simultaneously. The coefficient of consolidation was decreased around 40%, by increasing consolidation pressure and cement ratio to 300kPa and 50%, respectively (Figure 6).
Page 1 and 2: Compressibility Characteristics of
Page 3 and 4: Vol. 14, Bund. C 3 of island Japan,
Page 5: Vol. 14, Bund. C 5 a b Figure 3: (a
Page 9 and 10: Vol. 14, Bund. C 9 Ratio of compres
Page 11 and 12: Vol. 14, Bund. C 11 compressibility
Page 13: Vol. 14, Bund. C 13 25. Mesri, G. a

Compressibility Characteristics of Fibrous Tropical Peat ... - Ejge.com

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?