Figure 1
Peatlands in Poland and the location of the study area (based on Majtyka, 2013).
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 |
| 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 | |
Figure 2
Set of oedometers used for the tests.
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 ρs (g/cm3) | 1.443 | 1.473 | 1.530 | 1.461 | 1.524 | 1.489 | 1.474 | 1.492 |
| Natural water content wn (%) | 828.3 | 465.4 | 335.7 | 449.0 | 315.8 | 451.4 | 236.5 | 320.2 |
| Organic content Iom (%) | 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 | |||||
Figure 3
The relation between organic content Iom and natural water content wn.
Figure 4
The relation between bulk density ρ and initial void ratio e0.
Figure 5
The relation between natural water content wn and the initial void ratio e0.
Figure 6
The relation between vertical strain ɛv and effective vertical stress σv′.
Table 3
Averaged values of the constrained modulus of the tested peat.
| Vertical stress (kPa) | Constrained modulus Eoed (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 |
Figure 7
Vertical strain ɛv versus time t depending on the stress level σv for (a) fibric peat, (b) hemic peat, (c) sapric peat.
Figure 8
The relation between (a) void ratio e and effective vertical stress σv′ and (b) effective vertical stress σv′ and void ratio e.
Figure 9
The relation between compression index Cc and (a) natural water content wn and (b) initial void ratio e0.
Figure 10
Secondary compression index Cα versus compression index Cc.