## 3 Results and Discussion
### Test Results of Overturning and Sliding Resistance  
Anti-overturning and sliding tests were conducted for the scenarios, and the key experimental results are summarized in Table 5. The horizontal forces acting on the platform model post-penetration were measured and scaled to the prototype dimensions based on the model scale ratios for both clay and sand. Figure 18 illustrates the overall horizontal sliding resistance and inclination angle versus sliding displacement, while Figures 19 and 20 give the horizontal sliding resistance and bending moments relative to vertical forces for spudcan legs in clay and sand, respectively. The following experimental phenomena were obtained via comparative analysis:  
1. In clay, spudcan penetration depth variation exerted a limited influence on the vertical bearing capacity but significantly enhanced the sliding resistance, aligning with the horizontal bearing characteristics of mat foundations on inclined clay seabels reported  
Figure 14: Surrounding soil displacement vector diagram of clay at typical penetration depths.  
by [PERSON] et al. [16] via centrifuge testing. However, sand exhibited a 2-5 times greater peak sliding resistance despite shallower penetration. This peak occurred later in sand than in clay, followed by subsequent resistance reduction. Clay maintained near-constant resistance after peak attainment.
2. Comparison with theoretical methods (Equations (5)-(9)) indicated general agreement between the experimental sliding resistance values and computational results for both soil types, excepting minor deviations (<15%) in the LC_S1 sand case.
3. Under increasing horizontal loading, all platforms exhibited combined sliding and tilting regardless of the soil type or penetration depth. Clay soils demonstrated near-linear tilt angle progression, with tilt magnitudes at equivalent sliding distances being 8-10 times greater than in sand.
4. During integrated overturning-sliding resistance states, the compressed spudcans (#3 and #4) consistently sustained higher horizontal sliding resistance and vertical axial forces than the tensioned spudcans (#1 and #2). For the LC_S1 sand case, the shallow embedment of the #1 and #2 spudcans resulted in frictional resistance predominantly developing at the spudcan base, supplemented by limited horizontal resistance from compacted soil mounds (Figure 18b).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Type** & **Case** & **Penetration** & **Peak Sliding Resistance (t)** & \begin{tabular}{c} **Peak Location** \\ **(m)** \\ \end{tabular} & \begin{tabular}{c} **Max Tilt at** \\ **6 (m) Sliding** \\ \end{tabular} \\ \hline Clay & \begin{tabular}{c} LC\_C1 \\ LC\_C2 \\ \end{tabular} & \begin{tabular}{c} 1 \(L\) \\ \(2\,L\) \\ \end{tabular} & \begin{tabular}{c} 560 \\ \(1430\) \\ \end{tabular} & \begin{tabular}{c} 0.5 \\ \(1.8\) \\ \end{tabular} & \begin{tabular}{c} \(5.2^{\circ}\) \\ \(5.5^{\circ}\) \\ \end{tabular} \\ \hline Sand & \begin{tabular}{c} LC\_S1 \\ LC\_S2 \\ \end{tabular} & \begin{tabular}{c} 0 \(L\) \\ \(0.15\,L\) \\ \end{tabular} & \begin{tabular}{c} 2946 \\ \(3026\) \\ \end{tabular} & \
\begin{tabular}{c} 2.3 \\ \(2.0\) \\ \end{tabular} &
\begin{tabular}{c} 0.7\({}^{\circ}\) \\ \(0.55^{\circ}\) \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 5: Comparative analysis of anti-overturning and sliding test results.  
Figure 15: Variation curves of spudcan penetration resistance with depth in sand: (**a**) grid size convergence analysis; (**b**) penetration speed convergence analysis.  
The substantially lower horizontal sliding resistance yet greater tilt angles and penetration depths in clay versus sand were attributed to clay's lower bearing capacity (as shown in the Penetration Resistance Analysis Section). This led to the more pronounced settlement of the compressed spudcans (#3 and #4), resulting in significant tilting despite smaller overall horizontal loads.