# Investigation of Earthquake-Induced Pipe Damage in Liquefiable Soils
## 4 Evaluation of Pipeline Damage Caused by Earthquake in the Iskenderun Region
### Discussion of Results with Numerical Analysis of 3115 Station Data for Study Area 1
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Sample** & **Layer** & **\(\sigma_{\mathbf{v^{\prime}}}\)** & **C\({}_{\mathbf{N}}\)** & **(N\({}_{\mathbf{1}}\))\({}_{\mathbf{60}}\)** & **Fines (\%)** & **\(\sigma_{\mathbf{v}}\)** & **r\({}_{\mathbf{d}}\)** & **CSR** & **CRR** & **Fs** \\
**Depth (m)** & **Represented** & **67.5** & 1.1 & 8 & – & 142.5 & 0.94 & 0.51 & 0.10 & 0.27 \\
**7.50** & **81.0** & 1.1 & 8 & – & 171 & 0.93 & 0.50 & 0.10 & 0.28 \\
**10.50** & **Silty CLAY** & 94.5 & 1.0 & 10 & – & 199.5 & 0.89 & 0.48 & 0.11 & 0.34 \\
**12.00** & **(Alluvium)** & 108.0 & 1.0 & 10 & – & 228 & 0.85 & 0.46 & 0.11 & 0.36 \\
**13.50** & **121.5** & 0.9 & 10 & – & 256.5 & 0.81 & 0.44 & 0.11 & 0.37 \\
**15.00** & **135.0** & 0.9 & 11 & – & 285 & 0.77 & 0.41 & 0.12 & 0.42 \\ \hline \end{tabular}
\end{table} 
Table 3: Table of the liquefaction safety analysis for the borehole of ISK-113. Figure 14: (**a**) Soil profile of Study Area 1/borehole of ISK-113 with SPT N30 values and MASW-131 result from Microzonation Survey Report [60] (Borehole Coordinate of ISK-113 (N: 519684, E: 4059531/ITRF-96 Datum 36\({}^{\circ}\)); (**b**) Safety factor for liquefaction. Figure 15: Plaxis analysis model with base residual soil (extremely weathered rock) or intact rock layer. The model shown in Figure 15 consists of 6236 15-node triangular elements. In this model, the average element size is 0.858 m, and seismic record data were applied in the analysis at equal intervals of 0.01 s up to 99.9 s. Since there was no bedrock at the model's base, 'none' boundary conditions were selected at the base. The soil and pipe material properties are presented in Tables 1 and 2, respectively. A damping ratio of 2% was selected for liquefiable soil layers. When the model width was expanded from 50 m (1H) to three times the layer thickness (3H), i.e., 120 m, the model created (Figure 15) used 15,017 15-noded triangular elements, and the average element size was 0.8551 m. The boundary conditions for the model were selected as 'none' at the base. As can be seen in Figure 16b, the numerical analysis conducted in Study Area 1 showed that liquefaction occurred in the soil, as the excess pore water pressure ratio at a distance in the far field at the bottom of the pipe, Ru = 1. In Figure 16c, during the first 50 s of the earthquake in the 50 m wide model, an uplift of 50 mm was determined in the \(\O\) 1500 mm diameter pipe. Between 50 and 60 s, the layers beneath the pipe underwent an approximately 0.17 m downward displacement due to the overall liquefaction effect in the surrounding soil, followed by a rise of 3.6 cm (Figure 16c). In the analysis conducted for a 2000 mm diameter pipe under the same conditions, an uplift of 2 cm occurred within the first 50 s. Subsequently, between 50 and 60 s, there was downward displacement in the pipe, and after the 60 s mark, an uplift of 0.15 m was calculated (Figure 16c). After the earthquake, following the settlement and upward displacements in the field, the \(\O\) 2000 mm pipe returned to its initial position in the model (Figure 16c). Since the effect of the analysis boundaries on the behavior of the pipe was determined, when the analyses were repeated after expanding the model boundaries, it was observed that the pipe was less affected by the boundary conditions (Figure 16d). As shown in Figure 17, in 50 m and 120 m wide models, for the DC \(\O\) 1500 mm diameter pipe, the downward displacements (settlements) at the ground surface 10 m away from the pipe were calculated as 1.25 m and 0.16 m, respectively (Figure 17a,b). In the 50 m wide model in Study Area 1, downward displacements of up to 2 m were calculated at the boundaries, and these settlements also affected the zone around of the pipe (Figure 17a). The high downward displacement immediately next to the pipe indicates that the boundary conditions affected the structure. Figure 16c,d present the results of the analyses conducted with the 50 m and 120 m wide model, demonstrating the effect of model width and pipe diameter on the uplift behavior.