Effect of fibre content on the geotechnical properties of peat

Iwona Chmielewska

Detalles de publicación y publicación

Studia Geotechnica et Mechanica

Detalles de la revista

Formato: Revista
eISSN: 2083-831X
Primera edición: 09 Nov 2012
Calendario de la edición: 4 veces al año
Idiomas: Inglés

Organic soils are classified based on the content of organic matter (Shotyk, 1992). 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 water-saturated 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., 2011b, 2014). The elemental composition of peat depends on the botanical composition and the degree of decomposition (Shotyk, 1988). In terms of geotechnical engineering, peat is recognised as a material with high porosity, low shear strength and high compressibility (Rahgozar and Saberian, 2016; Wong et al., 2008). All of these engineering characteristics are related to the high natural water content (more than 200%) and very high organic matter content (even more than 75%) of peat (ASTM, 2007; Huat, 2004; Kazemian et al., 2011; Rahgozar and Saberian, 2016).

Peat deposits are formed when organic matter accumulates more rapidly than it decomposes, which is mainly connected with the ecosystem and climate conditions (Rahgozar and Saberian, 2016). Peatlands are found throughout the world and constitute 5%–8% of the land surface of the earth (Huat et al., 2011b; Mesri and Ajlouni, 2007). They occur in the temperate and cold regions in countries such as Canada, Finland, Sweden and Norway; however, 8%–11% of global peat deposits are in tropical or subtropical regions. Peatlands are also found in the USA, China, Germany and Poland (Malawska et al., 2006; Mesri and Ajlouni, 2007; Schulz et al., 2019; Szajdak et al., 2020).

The properties of peat depend on its botanical composition, fibre content and the degree of decomposition of the plant remains (Rezanezhad et al., 2016). Several methods of determining the degree of decomposition (humification) of peat have been reported in the literature (Farnham and Finney, 1965; Zaccone et al., 2018). However, one of the most well-known and commonly used field tests used to classify peat soils based on their decomposition is the 10-step von Post scale, where H1 refers to the least and H10 to the most decomposed peat (Huat et al., 2011a, b; Long, 2005; O’Kelly and Pichan, 2013; Rezanezhad et al., 2016). In practice, the degree of decomposition of peat using von Post scale is determined based on the visual inspection of its structure and on the squeezing test result.

The United States Department of Agriculture (USDA) compresses the von Post scale into three levels and divides peat based on the fibre content into fibric (fibrous), hemic (semi-fibrous) and sapric (amorphous) (USDA, 1999). Fibrous peat is the least humified (H1–H4 on the von Post scale) and consists of undecomposed distinct fragments of plant structure. It has more than 66% of fibres (ASTM, 2007) and is brown to brownish-yellow in colour (Larsson, 1996). Hemic peat has a medium degree of decomposition (H5–H6) and a recognisable structure. The fibre content of semi-fibrous peat is in the range from 33% to 66%. It is usually brown (Larsson, 1996). Sapric peat is highly humified (H7–H10). It is composed of less than 33% of very indistinct or invisible plant fibres (ASTM, 2007; Huat et al., 2011b; Larsson, 1996). It has a dark brown to black colour.

It has been recognised that the degree of decomposition and the fibre content determine the physical and mechanical properties of peat (O’Kelly and Pichan, 2013). The direct effects of fibre content on the geotechnical properties have not been investigated sufficiently (Hobbs, 1986). However, the main correlations are known and are presented in the literature. According to Huat et al. (2011b), the decomposition process causes decrease in organic matter and changes in peat structure. During decomposition, the structure of peat changes from highly porous and cellular to amorphous. The voids in peat are mostly saturated (O’Kelly and Pichan, 2013). Hence, fibric peat is characterised by a higher initial void ratio and natural water content in comparison to sapric and hemic peat. O’Kelly and Pichan (2013) have pointed out that particle and bulk densities of peat are strongly connected with the degree of decomposition and/or high mineral content. Higher values of bulk and particle densities generally indicate higher degree of decomposition and mineral content (Huat et al., 2011b). Due to the very high initial void ratio, the compressibility of fibric peat is much higher than the compressibility of sapric and hemic peat. Moreover, the decomposition process may reduce the long-term compression of peat soil (Berry, 1983).

The aim of the study was to determine the geotechnical properties of peat and relate them to the fibre content. The study included an experimental investigation on the physical properties of peat, such as unit weight, water and organic contents, degree of humification and fibre content. Consolidation and compressibility characteristics were also determined. The characteristics of peat have been related to the results presented in the literature.

Materials and methods

2.1

Peat sampling

The peat soil tested in this study was collected from the peatland in the north-eastern Poland, 250 km north-east of Warsaw. The area under consideration is located in the lake region within the river basin. Figure 1 shows the occurrence of peatlands in Poland and the location of the study area. The subsoil profile of considered peatland consists of peat with a thickness of about 1–7 m. Below the peat layer, glacial sediments, mainly in the form of silt and sand, are deposited. The water level is at a depth from 0.1 to 1.5 m below the ground surface.

Peatlands in Poland and the location of the study area (based on Majtyka, 2013).

The peat was sampled with thin wall cylinders with a diameter of 70 mm. The cylinders were pressed into the subsoil in a vertical direction. Samples were collected from eight different depths, 1.0, 1.4, 1.9, 2.3, 3.1, 3.6, 4.7 and 5.0 m, below the ground surface, over an area of approximately 2500 m². A total of 40 samples were tested. The results presented in the study are the average test results for each group of peat samples collected from a certain depth.

2.2

Physical properties

The bulk and particle densities, natural water content, organic content, initial void ratio and the degree of decomposition were investigated as the physical properties of peat. Tests were performed on the samples with natural water content and natural structure. The bulk and particle densities and the natural water content were determined in accordance with the international standards (ISO 17892-1:2014, ISO 17892-2:2014, ISO 17892-3:2015). The determination of the water content was carried out according to the procedure used commonly in soil testing. The organic content of peat was determined using the method of loss on ignition (LOI) in accordance with the European standard (EN 15935:2012). The method is widely used by researchers and consists of strongly heating the oven-dried soil sample at a specified temperature (Heiri et al., 2001; Hoogsteen et al., 2015). The temperature of 550°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): (1) $I_{om} = 0.0592 w_{n} + 54.34$ {I_{om}} = 0.0592{w_n} + 54.34 where w_n is the natural water content in percentage.

The degree of decomposition of peat was determined using the von Post scale. Table 1 shows the categories of peat based on the squeezing and visual tests results (Landva and Pheeney, 1980).

Table 1

Degree of decomposition of peat soil based on the von Post scale (Landva and Pheeney, 1980).

Peat classification		Decomposition	Plant structure	Material extruded on squeezing (passing between fingers)
Fibric peat	H1	None	Easily identified	Clear, colourless water
	H2	Insignificant	Easily identified	Yellowish water
	H3	Very slight	Still identifiable	Brown, muddy water
	H4	Slight	Not easily identified	Dark brown, muddy water
Hemic peat	H5	Moderate	Recognisable, but vague	Muddy water and some peat
Hemic peat	H6	Moderately strong	Indistinct	About one-third of peat squeezed out, dark brown water
Sapric peat	H7	Strong	Faintly recognisable	About one-half of peat squeezed out, very dark brown water
	H8	Very strong	Very indistinct	About two-thirds of peat squeezed out, also some pasty water
	H9	Nearly complete	Almost unrecognisable	Nearly all the peat squeezed out as a paste
	H10	Complete	No discernible	All the peat passes between the fingers, no free water visible

2.3

Consolidation and compressibility characteristics

The consolidation and compressibility characteristics of peat were determined in an oedometer by incremental loading. Tests were carried out on cylindrical samples with an initial height of 20 mm and a diameter 63.5 mm using a set of oedometers with automatic registration of displacement sensor readings presented in Figure 2. The peat samples were tested in non-deformable rings with top and bottom porous stones. Tests were performed in accordance with the international standard (ISO 17892-5:2017) at different effective vertical stresses σ_v′: 15, 32, 64, 96, 128 and 256 kPa. The maximum stress applied to the sample depended on the peat compressibility and the technical capabilities of the laboratory equipment.

With the vertical stress increment, the height of the sample and the void ratio of soil decrease. When the initial void ratio e₀ is known, the void ratio e at any stage of the oedometer test can be calculated from the equation (Head, 1994) (2) $e = e_{0} - (Δ H / H_{0}) \cdot (1 + e_{0}) = e_{0} - ε_{v} \cdot (1 + e_{0})$ e = {e_0} - \left( {\Delta H/{H_0}} \right) \cdot \left( {1 + {e_0}} \right) = {e_0} - {\varepsilon _v} \cdot \left( {1 + {e_0}} \right) where ΔH is the change in the sample height as a result of the application of stress, H₀ is the initial height of the sample and ɛ_v is the vertical strain.

Based on the oedometer tests, the constrained modulus, compression and secondary compression indexes of peat were determined. The constrained modulus was determined by measuring the sample height changes under an applied stress. The constrained modulus E_oed can, therefore, be calculated from the formula (3) $E_{oed} = Δ σ_{v}^{'} / ε_{v} = (Δ σ_{v}^{'} H) / Δ H$ {E_{oed}} = \Delta \sigma _v^\prime /{\varepsilon _v} = \left( {\Delta \sigma _v^\prime H} \right)/\Delta H where Δσ_v′ is the effective vertical stress increment and H is the height of the sample before the stress increment.

The compression index C_c is one of the most important parameters in the analysis of primary consolidation of soil. It is used to predict the foundation settlements. The parameter describes the change in the void ratio Δe as a function of the change in vertical effective stress plotted in the logarithmic scale Δlog σ_v′, C_c = Δe/Δlog σ_v′.

The number of correlations between the compression index and other physical parameters of soil (water content, void ratio, liquid or plastic limit) is known. The following dependencies can be used to predict the compression index in peat and other organic soils: C_c = 0.01w_n (Mesri and Ajlouni, 2007), C_c = 0.0115w_n (Moran et al., 1958), and C_c = 0.35·(e₀ − 0.5) (Hough, 1957).

The secondary compression index C_α is often more significant in peat than in other soils because of the relatively short duration of the primary consolidation and the long-term secondary consolidation of peat deposits (Mesri et al., 1997). It can be defined as the tangential slope of the e □ log t curve at any particular time t after the end of primary consolidation. It is directly related to the compression index (Mesri and Castro, 1987; Mesri and Godlewski, 1977) and stress (Jiang et al., 2020). The secondary compression index can be determined from the equation (4) $C_{α} = (Δ e / Δ log t) = (Δ ε / Δ log t) (1 + e_{0})$ {C_\alpha } = \left( {\Delta e/\Delta \log t} \right) = \left( {\Delta \varepsilon /\Delta \log t} \right)\left( {1 + {e_0}} \right)

Results and discussion

3.1

Physical properties

Table 2 shows the physical properties of the tested peat. Based on the degree of decomposition, peat from the peatland in north-eastern Poland was divided into fibric, hemic and sapric. Peat from a depth of 3.1 m, designated as P1, was classified as fibric, peat from the depths 1.9, 2.3, 3.6, 4.7 and 5.0 m below the ground surface (peat P2–P6) was classified as as hemic and peat designated as P7 and P8 from the depths 1.0 and 1.4 m was classified as sapric.

Table 2

Physical properties of the tested peat.

Peat designation	P1	P2	P3	P4	P5	P6	P7	P8
Depth of sampling (m)	3.1	1.9	2.3	3.6	4.7	5.0	1.0	1.4
Bulk density ρ (g/cm³)	1.010	1.045	1.039	1.029	1.034	1.031	1.127	1.112
Particle density ρ_s (g/cm³)	1.443	1.473	1.530	1.461	1.524	1.489	1.474	1.492
Natural water content w_n (%)	828.3	465.4	335.7	449.0	315.8	451.4	236.5	320.2
Organic content I_om (%)	94.86	90.73	83.42	92.39	84.16	88.57	90.61	88.23
Initial void ratio e₀ (−)	12.26	6.969	5.415	6.794	5.156	6.963	3.399	4.638
Degree of decomposition	H3	H5	H6	H5	H6	H5	H8	H7
Peat classification	Fibric	Hemic					Sapric

It can be observed in Table 2 that the lowest bulk density (ρ = 1.010 g/cm³) was estimated for fibric peat, whereas it was the highest (ρ = 1.112 and 1.127 g/cm³) for sapric peat. The bulk density of hemic peat varied from 1.029 to 1.039 g/cm³. The estimated values were within the range reported in the literature (ρ = 0.80–1.43 g/cm³) (Huat et al., 2011b; Rahgozar and Saberian, 2016; Wong et al., 2008). However, even lower values of bulk density have been reported by Zaccone et al. (2017, 2018). The particle density of the tested peat was determined to be 1.443–1.530 g/cm³, whereas the particle density presented in the literature varies from 1.23 to 1.64 g/cm³ (Boylan et al., 2008; Rahgozar and Saberian, 2016; Wong et al., 2008). As expected, the fibric peat had the highest natural water content (w_n = 828.3%), whereas sapric had the lowest water content (w_n = 236.5% and 320.2%). The water content of hemic peat was in the range of 335.7%–465.4%. The water content of peat presented in the literature has a wide range of 200%–1950% (Mesri and Ajlouni, 2007; Rahgozar and Saberian, 2016; Wong et al., 2008, 2009). The organic content of the tested peat varied from 83.42% to 94.86% and was within the range presented in the literature (I_om = 65.00%–99.06%) (Lechowicz et al., 2018; Mesri and Ajlouni, 2007; Rahgozar and Saberian, 2016; Wong et al., 2008). The highest value of organic content was determined for fibric peat, which had the highest natural water content. Figure 3 shows the I_om–w_n dependence.

The relation between organic content I_om and natural water content w_n.

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. 3). The coefficient of determination R² of the linear regression fit was relatively low (R² = 0.442). The prediction of the organic content based on the water content using empirical correlations should be made cautiously.

It can be observed in Table 2 that the highest initial void ratio (e₀ = 12.26) was determined for fibric peat, whereas it was the lowest (e₀ = 3.399 and 4.638) for sapric peat. For hemic peat, the e₀ values ranged from 5.156 to 6.969. The initial void ratio of hemic and sapric peat was lower than that reported by researchers (e₀ = 7.28–14.2) (Mesri and Ajlouni, 2007; Rahgozar and Saberian, 2016; Wong et al., 2008). This may be connected with the high degree of decomposition of the peat soil investigated in this study.

Based on the results presented in Table 2, it can be concluded that the initial void ratio had an influence on the bulk density and the natural water content of peat. The ρ □ e₀ and w_n □ e₀ dependences are shown in Figures 4 and 5.

The relation between bulk density ρ and initial void ratio e₀.

It can be observed in Figure 4 that with the increase in void ratio (volume of voids), the bulk density of peat decreased. An empirical correlation between the bulk density and the initial void ratio was established (Fig. 4). The R² coefficient obtained for the regression fit line was 0.518. As expected, the natural water content of saturated peat increased with the increase in initial void ratio. The correlation between the w_n and e₀ parameters was determined and is shown in Figure 5. The coefficient of determination of the regression line estimated for w_n □ e₀ dependence was very high (R² = 0.993); thus, the prediction of the natural water content based on the initial void ratio of the tested peat would be possible with a high accuracy.

The relation between natural water content w_n and the initial void ratio e₀.

3.2

Consolidation and compressibility characteristics

Figure 6 shows the relation between vertical strain and effective vertical stress for fibric, hemic and sapric peat for the primary loading and unloading phases. Due to the high compressibility of the tested soil and the technical capabilities of the laboratory equipment, the maximum vertical stress applied to fibric, hemic and sapric peat was 96, 128 and 256 kPa, respectively.

The relation between vertical strain ɛ_v and effective vertical stress σ_v′.

The biggest change in height of the sample caused by stress increment was determined for fibric peat, whereas it was the lowest for sapric peat (Fig. 6). It can be observed in Figure 6 that the vertical strain during the primary loading phase obtained for fibric peat, depending on the stress level, was approximately two to four times greater than it was determined for sapric peat. For hemic peat, the difference was not so significant.

Based on the results of the oedometer tests, the constrained modulus at different vertical stresses was obtained (Table 3).

Table 3

Averaged values of the constrained modulus of the tested peat.

Vertical stress (kPa)	Constrained modulus E_oed (kPa)

	Fibric peat	Hemic peat	Sapric peat
15	181.7	266.9	683.8
32	111.6	179.9	321.5
64	186.8	224.7	348.5
96	327.4	Not investigated	Not investigated
128	Not investigated	534.0	428.0
256	Not investigated	Not investigated	738.9

The highest values of the constrained modulus were determined for sapric peat, whereas they were the lowest in fibric peat. It can be observed in Table 3 that the constrained modulus of sapric peat was even several times higher than the constrained modulus of fibric and sapric peat. The difference decreased with the increase in vertical stress.

For a complete consolidation analysis, the vertical strain should be related to time. The ɛ_v □ log t dependencies used for determining the secondary compression index are shown in Figure 7.

Vertical strain ɛ_v versus time t depending on the stress level σ_v for (a) fibric peat, (b) hemic peat, (c) sapric peat.

Figure 7 also shows the highest vertical strain and, therefore, the biggest compressibility of fibric peat in comparison to hemic and sapric peat.

The relations between void ratio and effective vertical stress are shown in Figure 8. The e values were calculated from Equation (2). Based on the results presented in Figure 8a, the compression index of fibric, sapric and hemic peat was determined.

The relation between (a) void ratio e and effective vertical stress σ_v′ and (b) effective vertical stress σ_v′ and void ratio e.

The biggest change in the void ratio with the stress increment was determined for fibric peat, whereas it was the lowest for sapric peat (Fig. 8). The percentage decrease in the e values in relation to e₀ for the primary loading phase at vertical stress up to 64 kPa was estimated to be 38% for fibric peat, 32% for hemic peat and 22% for sapric peat. The σ_v′ □ e dependence for fibric peat shown in Figure 8b is very close to that reported in the literature, σ_v′ = (40/e)^2.7 (Mesri and Ajlouni, 2007). Due to the low void ratio of hemic and sapric peat, the relation σ_v′ □ e estimated for them is slightly different, but still comparable to the values presented by researchers. The empirical correlations between vertical stress and void ratio along with R² coefficients were established and are presented in Figure 8b.

The values of compression index are shown in Figure 9. They were related to the natural water content and initial void ratio.

The relation between compression index C_c and (a) natural water content w_n and (b) initial void ratio e₀.

It can be observed in Figure 9 that C_c □ w_n and C_c □ e₀ correlations were established with a high reliability (R² = 0.973 and 0.966, respectively). The C_c value increased with the increase in w_n and e₀ values. The compression indexes of the tested peat could be predicted based on the natural water content or the initial void ratio from the equations: C_c = 0.007w_n and C_c = 0.67·(e₀ – 0.5). The obtained compression index is comparable to the values presented by researchers (C_c = 0.2–10) (Hough, 1957; Mesri and Ajlouni, 2007; Moran et al., 1958).

The secondary compression index of fibric, hemic and sapric peat and the C_α/C_c correlation are shown in Figure 10. The C_α values were determined for each level of vertical stress.

Secondary compression index C_α versus compression index C_c.

With a medium reliability (R² = 0.697), a relation between the secondary compression index and the compression index was established, C_α/C_c = 0.07. The determined C_α/C_c ratio for the peat is the same as that reported in the literature (C_α/C_c = 0.06 ± 0.01) (Mesri, 1986; Mesri et al., 1997; Samson and La Rochelle, 1972).

Conclusions

Based on the degree of decomposition, peat from the peatland in north-eastern Poland was divided into fibric, hemic and sapric peat. The following conclusions may be derived from the performed experimental study:

Fibric peat, with the highest fibre content, has the lowest bulk and particle densities and the highest natural water content, organic content and initial void ratio in comparison to hemic and sapric peat.

The following equations may be used for the prediction of the physical parameters of tested peat: I_om = 0.0143w_n + 83.06, ρ = −0.0114e₀ + 1.127, w_n = 68.04e₀ − 13.53.

The highest compressibility was found in fibric peat. The vertical strain during the primary loading phase obtained for fibric peat, depending on the stress level, was approximately two to four times greater than it was determined in sapric peat.

The constrained modulus of sapric peat was even several times higher than the constrained modulus of fibric and sapric peat. The difference decreased with the increase in vertical stress.

The empirical equations for predicting the compression index of tested soil based on the natural water content and the initial void ratio are C_c = 0.007w_n and C_c = 0.67·(e₀ − 0.5).

The C_α/C_c ratio for the investigated peat was 0.07.

The determined peat characteristics are close to those presented in the literature.

Experimental investigation about the properties of peat soil with additives is in the author's plans for future research.

Figuras y tablas

The relation between bulk density ρ and initial void ratio e0.

The relation between natural water content wn and the initial void ratio e0.

The relation between compression index Cc and (a) natural water content wn and (b) initial void ratio e0.

Degree of decomposition of peat soil based on the von Post scale (Landva and Pheeney, 1980).

Peat classification		Decomposition	Plant structure	Material extruded on squeezing (passing between fingers)
Fibric peat	H1	None	Easily identified	Clear, colourless water
	H2	Insignificant	Easily identified	Yellowish water
	H3	Very slight	Still identifiable	Brown, muddy water
	H4	Slight	Not easily identified	Dark brown, muddy water
Hemic peat	H5	Moderate	Recognisable, but vague	Muddy water and some peat
Hemic peat	H6	Moderately strong	Indistinct	About one-third of peat squeezed out, dark brown water
Sapric peat	H7	Strong	Faintly recognisable	About one-half of peat squeezed out, very dark brown water
	H8	Very strong	Very indistinct	About two-thirds of peat squeezed out, also some pasty water
	H9	Nearly complete	Almost unrecognisable	Nearly all the peat squeezed out as a paste
	H10	Complete	No discernible	All the peat passes between the fingers, no free water visible

Physical properties of the tested peat.

Peat designation	P1	P2	P3	P4	P5	P6	P7	P8
Depth of sampling (m)	3.1	1.9	2.3	3.6	4.7	5.0	1.0	1.4
Bulk density ρ (g/cm³)	1.010	1.045	1.039	1.029	1.034	1.031	1.127	1.112
Particle density ρ_s (g/cm³)	1.443	1.473	1.530	1.461	1.524	1.489	1.474	1.492
Natural water content w_n (%)	828.3	465.4	335.7	449.0	315.8	451.4	236.5	320.2
Organic content I_om (%)	94.86	90.73	83.42	92.39	84.16	88.57	90.61	88.23
Initial void ratio e₀ (−)	12.26	6.969	5.415	6.794	5.156	6.963	3.399	4.638
Degree of decomposition	H3	H5	H6	H5	H6	H5	H8	H7
Peat classification	Fibric	Hemic					Sapric

Averaged values of the constrained modulus of the tested peat.

Vertical stress (kPa)	Constrained modulus E_oed (kPa)

	Fibric peat	Hemic peat	Sapric peat
15	181.7	266.9	683.8
32	111.6	179.9	321.5
64	186.8	224.7	348.5
96	327.4	Not investigated	Not investigated
128	Not investigated	534.0	428.0
256	Not investigated	Not investigated	738.9

Referencias

[1] ASTM. (2007). Standard Classification of Peat Samples by Laboratory Testing. American Society for Testing and Materials, ASTM International, West Conshohocken. ASTM 2007 Standard Classification of Peat Samples by Laboratory Testing American Society for Testing and Materials, ASTM International West Conshohocken Search in Google Scholar

[2] Berry, P. L. (1983). Application of consolidation theory for peat to design of a reclamation scheme by preloading. Quarterly Journal of Engineering Geology and Hydrogeology, 16, 103–112. https://doi.org/10.1144/GSL.QJEG.1983.016.02.03 BerryP. L. 1983 Application of consolidation theory for peat to design of a reclamation scheme by preloading Quarterly Journal of Engineering Geology and Hydrogeology 16 103 112 https://doi.org/10.1144/GSL.QJEG.1983.016.02.03 10.1144/GSL.QJEG.1983.016.02.03 Search in Google Scholar

[3] Boylan, N., Jennings, P., Long, M. (2008). Peat failures in Ireland. Quarterly Journal of Engineering Geology and Hydrogeology, 41, 93–108. https://doi.org/10.1144/1470-9236/06-028 BoylanN. JenningsP. LongM. 2008 Peat failures in Ireland Quarterly Journal of Engineering Geology and Hydrogeology 41 93 108 https://doi.org/10.1144/1470-9236/06-028 10.1144/1470-9236/06-028 Search in Google Scholar

[4] Craig, R. F. (1992). Soil Mechanics, 5th ed. Chapman & Hall, London. CraigR. F. 1992 Soil Mechanics 5th ed. Chapman & Hall London 10.1007/978-1-4899-3772-8 Search in Google Scholar

[5] EN 15935:2012. Sludge, treated biowaste, soil and waste – Determination of loss on ignition. CEN, Brussels. EN 15935 2012 Sludge, treated biowaste, soil and waste – Determination of loss on ignition CEN Brussels Search in Google Scholar

[6] Farnham, R. S., Finney, H. R. (1965). Classification and properties of organic soils. Advances in Agronomy, 17, 115–162. https://doi.org/10.1016/S0065-2113(08)60413-7 FarnhamR. S. FinneyH. R. 1965 Classification and properties of organic soils Advances in Agronomy 17 115 162 https://doi.org/10.1016/S0065-2113(08)60413-7 10.1016/S0065-2113(08)60413-7 Search in Google Scholar

[7] Head, K. H. (1994). Manual of Soil Laboratory Testing. Volume 2: Permeability, Shear Strength and Compressibility Tests, 2nd ed. John Wiley & Sons, Inc., New York. HeadK. H. 1994 Manual of Soil Laboratory Testing. Volume 2: Permeability, Shear Strength and Compressibility Tests 2nd ed. John Wiley & Sons, Inc. New York Search in Google Scholar

[8] Heiri, O., Lotter, A. F., Lemcke, G. (2001). Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results. Journal of Paleolimnology, 25, 101–110. HeiriO. LotterA. F. LemckeG. 2001 Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results Journal of Paleolimnology 25 101 110 10.1023/A:1008119611481 Search in Google Scholar

[9] Hobbs, N. B. (1986). Mire morphology and the properties and behaviour of some British and foreign peats. Quarterly Journal of Engineering Geology and Hydrogeology, 19, 7–80. https://doi.org/10.1144/GSL.QJEG.1986.019.01.02 HobbsN. B. 1986 Mire morphology and the properties and behaviour of some British and foreign peats Quarterly Journal of Engineering Geology and Hydrogeology 19 7 80 https://doi.org/10.1144/GSL.QJEG.1986.019.01.02 10.1144/GSL.QJEG.1986.019.01.02 Search in Google Scholar

[10] Hoogsteen, M. J. J., Lantinga, E. A., Bakker, E. J., Groot, J. C. J., Tittonell, P. A. (2015). Estimating soil organic carbon through loss on ignition: effects of ignition conditions and structural water loss. European Journal of Soil Science, 66, 320–328. https://doi.org/10.1111/ejss.12224 HoogsteenM. J. J. LantingaE. A. BakkerE. J. GrootJ. C. J. TittonellP. A. 2015 Estimating soil organic carbon through loss on ignition: effects of ignition conditions and structural water loss European Journal of Soil Science 66 320 328 https://doi.org/10.1111/ejss.12224 10.1111/ejss.12224 Search in Google Scholar

[11] Hough, B. K. (1957). Basic Soils Engineering, 1st edn. The Ronald Press Company, New York. HoughB. K. 1957 Basic Soils Engineering 1st edn. The Ronald Press Company New York Search in Google Scholar

[12] Huat, B. B. K. (2004). Organic and Peat Soils Engineering, 1st edn. University Putra Malaysia Press, Serdang. HuatB. B. K. 2004 Organic and Peat Soils Engineering 1st edn. University Putra Malaysia Press Serdang Search in Google Scholar

[13] Huat, B. B. K., Asadi, A., Kazemian, S. (2009). Experimental Investigation on Geomechanical Properties of Tropical Organic Soils and Peat. American Journal of Engineering and Applied Sciences, 2, 184–188. https://doi.org/10.3844/ajeassp.2009.184.188 HuatB. B. K. AsadiA. KazemianS. 2009 Experimental Investigation on Geomechanical Properties of Tropical Organic Soils and Peat American Journal of Engineering and Applied Sciences 2 184 188 https://doi.org/10.3844/ajeassp.2009.184.188 10.3844/ajeassp.2009.184.188 Search in Google Scholar

[14] Huat, B. B. K., Kazemian, S., Prasad, A., Barghchi, M. (2011a). A study of the compressibility behavior of peat stabilized by DMM: Lab Model and FE analysis. Scientific Research Essays, 6, 196–204. HuatB. B. K. KazemianS. PrasadA. BarghchiM. 2011a A study of the compressibility behavior of peat stabilized by DMM: Lab Model and FE analysis Scientific Research Essays 6 196 204 Search in Google Scholar

[15] Huat, B. B. K., Kazemian, S., Prasad, A., Barghchi, M. (2011b) State of an art review of peat: General perspective. International Journal of Physical Sciences, 6, 1988–1996. https://doi.org/10.5897/IJPS11.192 HuatB. B. K. KazemianS. PrasadA. BarghchiM. 2011b State of an art review of peat: General perspective International Journal of Physical Sciences 6 1988 1996 https://doi.org/10.5897/IJPS11.192 Search in Google Scholar

[16] Huat, B. B. K., Prasad, A., Asadi, A., Kazemian, S. (2014). Geotechnics of Organic Soils and Peat. Taylor & Francis Group, London. HuatB. B. K. PrasadA. AsadiA. KazemianS. 2014 Geotechnics of Organic Soils and Peat Taylor & Francis Group London 10.1201/b15627 Search in Google Scholar

[17] ISO 17892-1:2014. Geotechnical investigation and testing – Laboratory testing of soil – Part 1: Determination of water content. ISO, Geneva. ISO 17892-1 2014 Geotechnical investigation and testing – Laboratory testing of soil – Part 1: Determination of water content ISO Geneva Search in Google Scholar

[18] ISO 17892-2:2014. Geotechnical investigation and testing – Laboratory testing of soil – Part 2: Determination of bulk density. ISO, Geneva. ISO 17892-2 2014 Geotechnical investigation and testing – Laboratory testing of soil – Part 2: Determination of bulk density ISO Geneva Search in Google Scholar

[19] ISO 17892-3:2015. Geotechnical investigation and testing – Laboratory testing of soil – Part 3: Determination of particle density. ISO, Geneva. ISO 17892-3 2015 Geotechnical investigation and testing – Laboratory testing of soil – Part 3: Determination of particle density ISO Geneva Search in Google Scholar

[20] ISO 17892-5:2017. Geotechnical investigation and testing – Laboratory testing of soil – Part 5: Incremental loading oedometer test. ISO, Geneva. ISO 17892-5 2017 Geotechnical investigation and testing – Laboratory testing of soil – Part 5: Incremental loading oedometer test ISO Geneva Search in Google Scholar

[21] Jiang, N., Wang, C., Wu, Q., Li, S. (2020). Influence of Structure and Liquid Limit on the Secondary Compressibility of Soft Soils. Journal of Marine Science and Engineering, 8, 1–26. https://doi.org/10.3390/jmse8090627 JiangN. WangC. WuQ. LiS. 2020 Influence of Structure and Liquid Limit on the Secondary Compressibility of Soft Soils Journal of Marine Science and Engineering 8 1 26 https://doi.org/10.3390/jmse8090627 10.3390/jmse8090627 Search in Google Scholar

[22] Kazemian, S., Huat, B. B. K., Prasad, A., Barghchi, M. (2011). A state of art review of peat: Geotechnical engineering perspective. International Journal of Physical Sciences, 6, 1974–1981. https://doi.org/10.5897/IJPS11.396 KazemianS. HuatB. B. K. PrasadA. BarghchiM. 2011 A state of art review of peat: Geotechnical engineering perspective International Journal of Physical Sciences 6 1974 1981 https://doi.org/10.5897/IJPS11.396 Search in Google Scholar

[23] Landva, A. O., Pheeney, P. E. (1980). Peat fabric and structure. Canadian Geotechnical Journal, 17, 416–435. LandvaA. O. PheeneyP. E. 1980 Peat fabric and structure Canadian Geotechnical Journal 17 416 435 10.1139/t80-048 Search in Google Scholar

[24] Larsson, R. (1996). Organic Soils. In: Harlten, J., Wolski, W. (ed). Embankments on Organic Soils. Elsevier Science B.V., Amsterdam. LarssonR. 1996 Organic Soils In: HarltenJ. WolskiW. (ed). Embankments on Organic Soils Elsevier Science B.V. Amsterdam 10.1016/S0165-1250(96)80004-6 Search in Google Scholar

[25] Lechowicz, Z., Fukue, M., Rabarijoely, S., Sulewska, M. J. (2018). Evaluation of the Undrained Shear Strength of Organic Soils from a Dilatometer Test Using Artificial Neural Networks. Applied Sciences, 8, 1395–1411. https://doi.org/10.3390/app8081395 LechowiczZ. FukueM. RabarijoelyS. SulewskaM. J. 2018 Evaluation of the Undrained Shear Strength of Organic Soils from a Dilatometer Test Using Artificial Neural Networks Applied Sciences 8 1395 1411 https://doi.org/10.3390/app8081395 10.3390/app8081395 Search in Google Scholar

[26] Long, M. (2005). Review of peat strength, peat characterisation and constitutive modelling of peat with reference to landsides. Studia Geotechnica et Mechanica, 27, 67–90. LongM. 2005 Review of peat strength, peat characterisation and constitutive modelling of peat with reference to landsides Studia Geotechnica et Mechanica 27 67 90 Search in Google Scholar

[27] Majtyka, T. (2013). Peat deposits in Poland. http://commons.wikimedia.org/wiki/File:PL_torf_złoża.png. Accessed 9 April 2022. MajtykaT. 2013 Peat deposits in Poland http://commons.wikimedia.org/wiki/File:PL_torf_złoża.png. Accessed 9 April 2022. Search in Google Scholar

[28] Malawska, M., Ekonomiuk, A., Wiłkomirski, B. (2006). Chemical characteristics of some peatlands in southern Poland. Mires and Peat, 1, 1–14. MalawskaM. EkonomiukA. WiłkomirskiB. 2006 Chemical characteristics of some peatlands in southern Poland Mires and Peat 1 1 14 Search in Google Scholar

[29] Mesri, G. (1986). Discussion of ‘Postconstruction settlement of an expressway built on peat by precompression’. Canadian Geotechnical Journal, 23, 403–407. MesriG. 1986 Discussion of ‘Postconstruction settlement of an expressway built on peat by precompression’ Canadian Geotechnical Journal 23 403 407 10.1139/t86-059 Search in Google Scholar

[30] Mesri, G., Ajlouni, M. (2007). Engineering Properties of Fibrous Peats. Journal of Geotechnical and Geoenvironmental Engineering, 133, 850–866. https://doi.org/10.1061/(ASCE)1090-0241(2007)133:7(850) MesriG. AjlouniM. 2007 Engineering Properties of Fibrous Peats Journal of Geotechnical and Geoenvironmental Engineering 133 850 866 https://doi.org/10.1061/(ASCE)1090-0241(2007)133:7(850) 10.1061/(ASCE)1090-0241(2007)133:7(850) Search in Google Scholar

[31] Mesri, G., Castro, A. (1987). The C_α/C_c concept and K₀ during secondary compression. Journal of Geotechnical Engineering, 113, 230–247. MesriG. CastroA. 1987 The C_α/C_c concept and K₀ during secondary compression Journal of Geotechnical Engineering 113 230 247 10.1061/(ASCE)0733-9410(1987)113:3(230) Search in Google Scholar

[32] Mesri, G., Godlewski, P. M. (1977). Time- and stress-compressibility interrelationship. Journal of Geotechnical Engineering, 103, 419–430. MesriG. GodlewskiP. M. 1977 Time- and stress-compressibility interrelationship Journal of Geotechnical Engineering 103 419 430 10.1061/AJGEB6.0000421 Search in Google Scholar

[33] Mesri, G., Stark, T. D., Ajlouni, M. A., Chen, C. S. (1997). Secondary Compression of Peat with or without Surcharging. Journal of Geotechnical and Geoenvironmental Engineering, 123, 411–421. https://doi.org/10.1061/(ASCE)1090-0241(1997)123:5(411) MesriG. StarkT. D. AjlouniM. A. ChenC. S. 1997 Secondary Compression of Peat with or without Surcharging Journal of Geotechnical and Geoenvironmental Engineering 123 411 421 https://doi.org/10.1061/(ASCE)1090-0241(1997)123:5(411) 10.1061/(ASCE)1090-0241(1997)123:5(411) Search in Google Scholar

[34] Moran, Proctor, Mueser, Rutledge, P. C. (1958). Study of Deep Soil Stabilization by Vertical Sand Drains. Bureau of Yards and Docks, Department of the Navy, New York. Moran Proctor Mueser RutledgeP. C. 1958 Study of Deep Soil Stabilization by Vertical Sand Drains Bureau of Yards and Docks, Department of the Navy New York Search in Google Scholar

[35] O’Kelly, B. C., Pichan, S. P. (2013). Effects of decomposition on the compressibility of fibrous peat – A review. Geomechanics and Geoengineering, 9, 286–296. https://doi.org/10.1080/17486025.2013.804210 O’KellyB. C. PichanS. P. 2013 Effects of decomposition on the compressibility of fibrous peat – A review Geomechanics and Geoengineering 9 286 296 https://doi.org/10.1080/17486025.2013.804210 10.1080/17486025.2013.804210 Search in Google Scholar

[36] Rahgozar, M. A., Saberian, M. (2016). Geotechnical properties of peat soil stabilised with shredded waste tyre chips. Mires and Peat, 18, 1–12. https://doi.org/10.19189/MaP.2015.OMB.205 RahgozarM. A. SaberianM. 2016 Geotechnical properties of peat soil stabilised with shredded waste tyre chips Mires and Peat 18 1 12 https://doi.org/10.19189/MaP.2015.OMB.205 Search in Google Scholar

[37] Rezanezhad, F., Price, J. S., Quinton, W. L., Lennartz, B., Milojevic, T., Van Cappellen, P. (2016). Structure of peat soils and implications for water storage, flow and solute transport: A review update for geochemists. Chemical Geology, 429, 75–84. https://doi,org/10.1016/j.chemgeo.2016.03.010 RezanezhadF. PriceJ. S. QuintonW. L. LennartzB. MilojevicT. Van CappellenP. 2016 Structure of peat soils and implications for water storage, flow and solute transport: A review update for geochemists Chemical Geology 429 75 84 https://doi,org/10.1016/j.chemgeo.2016.03.010 10.1016/j.chemgeo.2016.03.010 Search in Google Scholar

[38] Samson, L., La Rochelle, P. (1972). Design and performance of an expressway constructed over peat by preloading. Canadian Geotechnical Journal, 9, 447–466. SamsonL. La RochelleP. 1972 Design and performance of an expressway constructed over peat by preloading Canadian Geotechnical Journal 9 447 466 10.1139/t72-044 Search in Google Scholar

[39] Schulz, C., Meier-Uhlherr, R., Luthardt, V., Joosten, H. (2019). A toolkit for field identification and ecohydrological interpretation of peatland deposits in Germany. Mires and Peat, 24, 1–20. https://doi.org/10.19189/MaP.2019.OMB.StA.1817 SchulzC. Meier-UhlherrR. LuthardtV. JoostenH. 2019 A toolkit for field identification and ecohydrological interpretation of peatland deposits in Germany Mires and Peat 24 1 20 https://doi.org/10.19189/MaP.2019.OMB.StA.1817 Search in Google Scholar

[40] Shotyk, W. (1988). Review of the inorganic geochemistry of peats and peatland waters. Earth-Science Reviews, 25, 95–176. https://doi.org/10.1016/0012-8252(88)90067-0 ShotykW. 1988 Review of the inorganic geochemistry of peats and peatland waters Earth-Science Reviews 25 95 176 https://doi.org/10.1016/0012-8252(88)90067-0 10.1016/0012-8252(88)90067-0 Search in Google Scholar

[41] Shotyk, W. (1992). Organic soils. In: Martini, I. P., Chesworth, W. (ed). Weathering, Soils, and Paleosols. Developments in Earth Surface Processes. Elsevier, Amsterdam. ShotykW. 1992 Organic soils In: MartiniI. P. ChesworthW. (ed). Weathering, Soils, and Paleosols. Developments in Earth Surface Processes Elsevier Amsterdam 10.1016/B978-0-444-89198-3.50014-3 Search in Google Scholar

[42] Skreczko, S., Szymczyk, A., Nadłonek, W. (2021). Impacts of vegetation and palaeohydrological changes on the n-alkane composition of a Holocene peat sequence from the Upper Vistula Valley (southern Poland). Journal of Soil Sediments, 21, 2709–2718. https://doi.org/10.1007/s11368-021-02981-4 SkreczkoS. SzymczykA. NadłonekW. 2021 Impacts of vegetation and palaeohydrological changes on the n-alkane composition of a Holocene peat sequence from the Upper Vistula Valley (southern Poland) Journal of Soil Sediments 21 2709 2718 https://doi.org/10.1007/s11368-021-02981-4 10.1007/s11368-021-02981-4 Search in Google Scholar

[43] Szajdak, L. W., Jezierski, A., Wegner, K., Meysner, T., Szczepański, M. (2020). Influence of Drainage on Peat Organic Matter: Implications for Development, Stability, and Transformation. Molecules, 25, 2587–2614. https://doi.org/10.3390/molecules25112587 SzajdakL. W. JezierskiA. WegnerK. MeysnerT. SzczepańskiM. 2020 Influence of Drainage on Peat Organic Matter: Implications for Development, Stability, and Transformation Molecules 25 2587 2614 https://doi.org/10.3390/molecules25112587 10.3390/molecules25112587732133032498453 Search in Google Scholar

[44] United States Department of Agriculture (USDA). (1999). Soil Taxonomy. A Basic System of Soil Classification for Making and Interpreting Soil Surveys, 2nd ed. United States Government Printing Office, Washington. United States Department of Agriculture (USDA) 1999 Soil Taxonomy. A Basic System of Soil Classification for Making and Interpreting Soil Surveys 2nd ed. United States Government Printing Office Washington Search in Google Scholar

[45] Wong, L. S., Hashim, R., Ali, F. H. (2008). Strength and Permeability of Stabilized Peat Soil. Journal of Applied Sciences, 8, 1–5. https://doi.org/10.3923/jas.2008.3986.3990 WongL. S. HashimR. AliF. H. 2008 Strength and Permeability of Stabilized Peat Soil Journal of Applied Sciences 8 1 5 https://doi.org/10.3923/jas.2008.3986.3990 10.3923/jas.2008.3986.3990 Search in Google Scholar

[46] Wong, L. S., Hashim, R., Ali, F. H. (2009). A Review on Hydraulic Conductivity and Compressibility of Peat. Journal of Applied Sciences, 9, 3207–3218. https://doi.org/0.3923/jas.2009.3207.3218 WongL. S. HashimR. AliF. H. 2009 A Review on Hydraulic Conductivity and Compressibility of Peat Journal of Applied Sciences 9 3207 3218 https://doi.org/0.3923/jas.2009.3207.3218 10.3923/jas.2009.3207.3218 Search in Google Scholar

[47] Zaccone, C., Lobianco, D., Shotyk, W., Ciavatta, C., Appleby, P. G., Brugiapaglia, E., Casella, L., Miano, T. M., D’Orazio, V. (2017). Highly anomalous accumulation rates of C and N recorded by a relic, free-floating peatland in Central Italy. Scientific Reports, 7, 1–10. https://doi.org/10.1038/srep43040 ZacconeC. LobiancoD. ShotykW. CiavattaC. ApplebyP. G. BrugiapagliaE. CasellaL. MianoT. M. D’OrazioV. 2017 Highly anomalous accumulation rates of C and N recorded by a relic, free-floating peatland in Central Italy Scientific Reports 7 1 10 https://doi.org/10.1038/srep43040 10.1038/srep43040532232128230066 Search in Google Scholar

[48] Zaccone, C., Miano, T. M., Shotyk, W. (2007). Qualitative comparison between raw peat and related humic acids in an ombrotrophic bog profile. Organic Geochemistry, 38, 151–160. https://doi.org/10.1016/j.orggeochem.2006.06.023 ZacconeC. MianoT. M. ShotykW. 2007 Qualitative comparison between raw peat and related humic acids in an ombrotrophic bog profile Organic Geochemistry 38 151 160 https://doi.org/10.1016/j.orggeochem.2006.06.023 10.1016/j.orggeochem.2006.06.023 Search in Google Scholar

[49] Zaccone, C., Plaza, C., Ciavatta, C., Miano, T. M., Shotyk, W. (2018). Advances in the determination of humification degree in peat since Achard (1786): Applications in geochemical and paleoenvironmental studies. Earth-Science Reviews, 185, 163–178. https://doi.org/10.1016/j.earscirev.2018.05.017 ZacconeC. PlazaC. CiavattaC. MianoT. M. ShotykW. 2018 Advances in the determination of humification degree in peat since Achard (1786): Applications in geochemical and paleoenvironmental studies Earth-Science Reviews 185 163 178 https://doi.org/10.1016/j.earscirev.2018.05.017 10.1016/j.earscirev.2018.05.017 Search in Google Scholar

Studia Geotechnica et Mechanica

Effect of fibre content on the geotechnical properties of peat

Iwona Chmielewska
Iwona Chmielewska

Publicado en línea: 09 Mar 2023

Volumen & Edición: AHEAD OF PRINT

Páginas: -

Recibido: 09 May 2022

Aceptado: 06 Dec 2022

Detalles de publicación y publicación

Studia Geotechnica et Mechanica

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Figuras y tablas

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Degree of decomposition of peat soil based on the von Post scale (Landva and Pheeney, 1980).

Physical properties of the tested peat.

Averaged values of the constrained modulus of the tested peat.

Referencias

Artículos Recientes

Studia Geotechnica et Mechanica

Effect of fibre content on the geotechnical properties of peat

Iwona ChmielewskaIwona Chmielewska

Publicado en línea: 09 Mar 2023

Volumen & Edición: AHEAD OF PRINT

Páginas: -

Recibido: 09 May 2022

Aceptado: 06 Dec 2022

Detalles de publicación y publicación

Studia Geotechnica et Mechanica

Vista previa del PDF

Artículo

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figuras y tablas

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Degree of decomposition of peat soil based on the von Post scale (Landva and Pheeney, 1980).

Physical properties of the tested peat.

Averaged values of the constrained modulus of the tested peat.

Referencias

Artículos Recientes

Iwona Chmielewska
Iwona Chmielewska