# An Investigation into the Influence of Sample Height on the Consolidation Behaviour of Dredged Silt
## 3 Test Results and Analysis
### Yield Stress of Soil Structure and Compression Index  
The mechanical characteristics of structural soil, such as dredged silt, vary significantly across stages before and after yielding. One crucial parameter in the assessment of dredged silt is the structural yield stress. [PERSON] [41] first introduced the idea of determining this yield stress using double logarithmic coordinates. Subsequent research by various scholars has affirmed the efficacy of this technique, establishing that the intersection point of the two linear graphs represents the yield stress of the soil structure [42; 43]. In our study, we employed [PERSON]'s double logarithmic coordinates method (\(\ln(1+e)\)-lgp) to ascertain the structural yield stress of the dredged silt.  
Figures 5-8 present the \(\ln(1+e)\)-lgp curves for soil samples of diverse dimensions. An examination of these figures reveals compression curves, which can be essentially delineated by two straight lines. Table 4 showcases the structural yield stress values derived from these curves for samples of varying heights. A consistent observation from  
Figure 4: Accumulative strains of samples with different heights under different consolidation pressures.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Consolidation** & **Accumulative** & **Accumulative** & **Accumulative** & **Accumulative** & **A-B** & **B-C** & **A-C** \\
**Pressure \(p\)** & **Strain A** & **Strain B** & **Strain C** & **(\%)** & **(\%)** & **(\%)** & **(\%)** \\
**(kPa)** & **(2 cm) (\%)** & **(3 cm) (\%)** & **(4 cm) (\%)** & **(**\%)** & **(\%)** & **(\%)** \\ \hline
5 & 20.315 & 19.997 & 19.755 & 0.318 & 0.242 & 0.560 \\
12.5 & 23.400 & 22.350 & 20.910 & 1.050 & 1.440 & 2.490 \\
25 & 26.140 & 25.197 & 23.715 & 0.943 & 1.482 & 2.425 \\
50 & 28.880 & 28.383 & 27.990 & 0.497 & 0.393 & 0.890 \\
80 & 31.795 & 30.450 & 29.208 & 1.345 & 1.242 & 2.587 \\
120 & 35.495 & 33.473 & 32.498 & 2.022 & 0.975 & 2.997 \\ \hline \end{tabular}
\end{table}
Table 3: Variation of accumulative strains of samples with different heights.  
Table 4 is that the yield stress of the soil samples remained relatively constant, averaging around 50 kPa, regardless of the sample height. This consistency underscores the notion that yield stress is a pivotal metric for gauging the structural integrity of soil. For identical soil compositions, structural strength predominantly hinges on the inherent characteristics, connectivity patterns, and arrangement of soil particles, rather than just sample size. The compression index, denoted as \(C_{\mathrm{c}}\), is calculated based on the gradient of the \(e\)-l\(g\) curve in the yielding phase of the soil structure, which closely mirrors a linear progression. Table 4 also presents the compression indices for soil samples at various heights. Notably, as the sample height escalated, the compression index \(C_{\mathrm{c}}\) experienced a decline. However, the disparities in compression indices across different sample sizes were marginal.  
Figure 5: \(\ln(1+e)\)-l\(g\) curves of soil samples.  
Figure 6: \(\ln(1+e)\)-l\(g\) curve of a soil sample of 2 cm height.