## 5 Previous Methods of Determining Soil Unit Weight  
Soil total unit weight (\(\gamma_{t}\)) is classified as the basic physical characteristics of both mineral and organic soils. This feature is most often determined in laboratory tests. Recently, many formulas appeared in the literature to determine the soil total unit weight on the basis of in situ tests, e.g., cone penetration tests (CPTU) and DMT investigations. The article describes the dependencies between (\(\gamma_{t}\)) and parameters determined from dilatometer tests (DMT). Although so far no database for (\(\gamma_{t}\)) has been presented, [PERSON] and [PERSON] (2019) have suggested that it should be estimated according to the \(I_{D}\) and \(E_{D}\) values (Figure 1).  
Similarly, a relationship was developed for the results of DMT tests to assess the soil total unit weight. These dependencies are presented in Equation (8) [(26; 27)]:  
\[\gamma_{t}\approx 1.12\times\gamma_{w}\times\left(\frac{E_{D}}{\sigma_{atm}} \right)^{0.1}\times I_{D}^{-0.05} \tag{8}\]  
where: \(\rho=\left(\gamma_{T}\middle/(\gamma_{w})\right.\), and \(\sigma_{atm}=\)100 kPa is atmospheric pressure.  
So far, attempts have been made to estimate the soil unit weight based on DMT tests for selected types of mineral soils [(28; 29)] or to develop new dependencies between the total unit weight and DMT indexes [(30)]. These studies focused mainly on natural clays with a soft or hard consistency. These soils are homogeneous, which is often associated with high groundwater level.  
\[\frac{\gamma}{\gamma_{w}}=1.31\left(\frac{p_{1}}{p_{a}}\right)^{0.164} \tag{9}\]  
[PERSON] et al. (30; 31) proposed a correlation to estimate the total unit weight in terms of \(p_{1}\) pressure from DMT. This model provides a fairly accurate prediction of laboratory results for soft to medium compact clays from the \"Lake Bonneville\" valley. The formula is as follows:  
Figure 1: Unit weight estimate from dilatometer (DMT) indexes \(E_{D}\) and \(I_{D}\)[(25)]. Reproduced with permission from [(25)], [PERSON], 2019.  
\[\frac{\gamma^{\prime}}{\gamma_{w}}=1.31\left(\frac{p_{1}}{p_{a}}\right)^{0.164} \tag{10}\]  
[PERSON] and [PERSON] [32] found that there is a relationship between soil total unit weight (\(\gamma_{t}\)), contact pressure (\(p_{0}\)), and depth (\(z\)) for clays in the range from normally consolidated (NC) to lightly preconsolidated (LOC), with soft to hard consistency. The newly defined slope parameter (\(m_{p0}=\Delta p_{0}/\Delta z\)) with a forced intersection equal to 0 has been set for homogeneous inorganic clays. It was found to be related with soil unit weight, as expressed by the following formulas in Equations (11) and (12):  
\[\gamma_{t}\left(kN/m^{3}\right)=\gamma_{w}+0.22\times m_{p0} \tag{11}\]  
\[m_{p0}(-)=\frac{\Delta_{p0}}{\Delta z} \tag{12}\]  
where:  
\(\gamma_{w}\)--water unit weight  
\(\Delta_{po}\) and \(\Delta z\)--slope parameters (\(p_{o}\) is the pressure and \(z\) is the depth)  
The cited authors have stated that in the case of inorganic clays, these formulas (Equations (11) and (12)) do not give adequate results for OL (Organic Low liquid limit) or OH (Organic High liquid limit) soils, or soils with a significant organic content. The values are based on data obtained mainly from inorganic and non-sensitive clays.