# Electromechanical Behavior of Afyonkarahisar Clay Under Varying Stress and Moisture Conditions
## 3 Test Results and Discussions
### Electrical Conductivity Under Different Water Contents and Varying Stress-Strain Conditions  
The analysis of the results indicates a similarity between the temporal evolution of stress and strain and the temporal variation of electrical conductivity under changing stress-strain conditions during the uniaxial compression test, across all three levels of water content. The values of electrical conductivity (\(EC\)) vary with the applied stress state and water content according to a trend that can be described using a simple exponential form, see Equation (5). \[EC=a\cdot e^{b\cdot(w/w_{L})}, \tag{5}\]  
Figure 5: Stress–strain and electrical conductivity–strain relationships (**left**), and stress–time and electrical conductivity–time relationships (**right**), obtained from uniaxial compression and electrical resistance tests on clay samples with varying water contents. Figure 6 illustrates the variation in electrical conductivity under different stress-strain conditions (for \(\sigma_{\text{u}}\) = 50, 75, 100, and 200 kPa) during uniaxial compression tests, and for different initial water contents (w = 10%, 20%, and 30%). A good agreement between the measurements is observed when the results are expressed in exponential form, suggesting a consistent relationship between electrical conductivity and applied stress across different moisture conditions. The values of the parameters a and b for different applied stress levels are summarized in Table 2.  
The relationships between electrical conductivity (\(EC\)) and water content (w) of soil samples subjected to varying stress-strain conditions during uniaxial compression tests are characterized by two parameters, a and b, as expressed in Equation (6). Equations (5) and (6) are derived from the integration of laboratory test data and established findings from the literature on shear strength and soil behavior, with particular reference to [PERSON] (2015) [PERSON] (2015). \[EC=a\cdot e^{b\cdot w}, \tag{6}\]  
These parameters capture the influence of applied stress levels on the dependence of electrical conductivity on moisture content. The specific values of parameters a and b for different applied stress levels are summarized in Table 2, providing insight into how mechanical loading affects the soil's electrochemical behaviour. \begin{table}
\begin{tabular}{c c c} \hline
**Stress \(\sigma\) (kPa)** & **a** & **b** \\ \hline
50 & 0.0011 & 0.1428 \\
75 & 0.0012 & 0.1405 \\
100 & 0.0020 & 0.1227 \\
200 & 0.0038 & 0.1068 \\ \hline \end{tabular}
\end{table} 
Table 2: Parameters a and b in Equation (4) for different stress levels. Figure 6: Electrical conductivity under varying stress–strain conditions during uniaxial compression tests and at different water contents. This section examines the influence of relative moisture content on the uniaxial compressive strength of clay (q\({}_{\mathrm{u}}\)) and the undrained shear strength (c\({}_{\mathrm{u}}\)). The focus is on the empirical relationship between cu/qu as a function of the relative water content w/w\({}_{\mathrm{L}}\) (where w is the water content and w\({}_{\mathrm{L}}\) the liquid limit), and its comparison with experimentally determined strength values. The findings indicate that cu/qu decreases significantly with increasing relative moisture content, reflecting a reduction in shear resistance due to the higher water content. For the investigated high-plasticity clay (CH), the variation in the internal friction angle with increasing moisture content was also analyzed, while cohesion was found to be negligible. In practical applications, a simplified empirical relationship is often used:  
\[\mathrm{c}_{u}=\mathrm{q}_{u}/2, \tag{7}\]  
This relationship was first proposed in the works of [PERSON] (1957) [27] and [PERSON] (1967) [28]. However, it is only valid for consolidated, saturated clays under undrained conditions. The relationship becomes less reliable when the moisture content or plastic properties of the soil change.