## 2 Methodology and Interpretation of Dilatometer Tests  
Dilatometer tests (DMT) were applied to recognize mineral and organic subsoils distinguished in the above-mentioned test sites. The details of the DMT test operation can be found in [2; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17]. During the DMT tests, \(A\), \(B\) and \(C\) readings are carried out as shown in Figure 1[18; 19]. \(A\), \(B\) and \(C\) readings are adjusted according to the inertia impact resistance of the membrane, which allows to determine pressures \(p_{0}\), \(p_{1}\) and \(p_{2}\) (equ. \(2\div 4\)). The pressures \(p_{0}\), \(p_{1}\) and \(p_{2}\) together with the calculated value of the vertical effective stress component \(\sigma^{{}^{\prime}}_{\infty}\) and the pore water pressure \(u_{o}\) are used to determine the following dilatometer indexes (equ. \(5\div 8\)) [13; 17; 13]:  
* 0.05 mm corrected pressure treading in DMT \(p_{0}\) \[p_{o}=1.05(A-Z_{M}+\Delta A)-0.05(B-Z_{M}-\Delta B)\] (2)
* 1.10 mm corrected pressure treading in DMT \(p_{1}\) \[p_{1}=B-Z_{M}-\Delta B\] (3)
* corrected third reading in DMT \(p_{2}\) \[p_{2}=C-Z_{M}-\Delta A\] (4)
* Material index \(I_{D}\) \[I_{d}=\frac{P_{1}-P_{0}}{P_{0}-u_{0}}\] (5)
* Horizontal earth pressure index \(K_{D}\) \[K_{d}=\frac{P_{0}-u_{0}}{\sigma^{\prime}_{0}}\] (6)
* Dilatometer modulus \(E_{D}\) \[E_{d}=34.7\cdot(P_{1}-P_{0})\] (7)
* Water pressure index \(U_{D}\) \[U_{d}=\frac{P_{2}-u_{0}}{P_{0}-u_{0}}\] (8)  
where:  
\(p_{0}\)--\(A\)-pressure reading, corrected for \(Z_{m}\), \(\Delta A\) membrane stiffness at 0.05 mm expansion, and 0.05 mm expansion itself, to estimate the total soil stress acting normal to the membrane immediately before its expansion into the soil (0.00 mm expansion). \(p_{1}\)--\(B\)-pressure reading corrected for \(Z_{m}\) and \(\Delta B\) membrane stiffness at 1.10 mm expansion to give the total soil stress acting normal to the membrane at 1.10 mm membrane expansion. \(p_{2}\)--\(C\)-pressure reading corrected for \(Z_{m}\) and \(\Delta A\) membrane stiffness at 0.05 mm expansion and used to estimate pore-water pressure. \(\sigma^{{}^{\prime}}_{\infty}\)--vertical effective stress at the centre of the membrane before insertion of the DMT blade. \(u_{0}\)--pore-water pressure acting at the centre of the membrane before insertion of the DMT blade (often assumed as hydrostatic below the water table surface). \(Z_{m}\)--gage pressure deviation from zero when vented to atmospheric pressure (an offset used to correct pressure readings to the true gage pressure). In order to reduce the necessity of using various types of equipment, field research methods are being sought that allow interpretation of the results obtained in a wide range. One of the field studies that meets this requirement is the [PERSON] dilatometer [1], used more often in the country. The biggest advantage of studying the dilatometer is fast and not very complicated measurement, on the basis of which it is possible to determine the profiles of many soil parameters. The interpretation of ground parameters is based on the use of empirical relationships linking the results of measurements to the values of ground parameters [20; 21]. It is standardized in the ASTM and the Eurocode [3]. The DMT has been the object of a detailed monograph by the ISSMGE Technical Committee TC16 [22; 23; 24]. In the case of dilatometer (DMT) investigations, the diagrams generally developed by [PERSON] were commonly used [1; 2] (Table 1, Figure 2). [PERSON] [1] proposed a soil classification based on the I\({}_{\rm D}\) material index where the value of the material index \(I_{D}\) < 0.10 points to peat or sensitive clays with no clear discrimination between them. However, it should be pointed out that the diagram was developed based mainly on soil mineral tests. The Marchetti and Crapps diagram shows the relationship between the material index \(I_{D}\) and the dilatometer modulus \(E_{D}\) (in a log-log scale).