# 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 with 3115 Station Data for Study Area 2
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Sample Depth (m)**} & \multicolumn{1}{c}{**Layer**} & \multirow{2}{*}{**BSCS**} & \multirow{2}{*}{\(\sigma\mathbf{v^{\prime}}\)} & \multirow{2}{*}{**C\({}_{\mathbf{N}}\)**} & \multirow{2}{*}{**(\(\mathbf{N_{1}}\))\({}_{\mathbf{60}}\)**} & \multirow{2}{*}{**Fines (\%)**} & \multirow{2}{*}{**\(\sigma\mathbf{v}\)**} & \multirow{2}{*}{**rd**} & \multirow{2}{*}{**CSR**} & \multirow{2}{*}{**CRR**} & \multirow{2}{*}{**Fs**} \\ \hline
1.50 & Sandy CLAY & & 13.5 & 1.7 & 27 & – & 28.5 & 0.99 & 0.53 & 0.33 & 0.89 \\
3.00 & Sandy CLAY & & 27.0 & 1.4 & 23 & – & 57 & 0.98 & 0.52 & 0.25 & 0.70 \\
4.50 & & & 40.5 & 1.3 & 9 & – & 85.5 & 0.97 & 0.52 & 0.10 & 0.29 \\
6.00 & & CH & 54.0 & 1.2 & 5 & 70.9 & 114 & 0.95 & 0.51 & & \\
7.50 & & & 67.5 & 1.1 & 8 & – & 143 & 0.94 & 0.50 & 0.10 & 0.27 \\
9.00 & & & 81.0 & 1.1 & 6 & – & 171 & 0.93 & 0.50 & 0.08 & 0.23 \\
10.50 & Gravelly & & 94.5 & 1.0 & 6 & – & 200 & 0.89 & 0.48 & 0.08 & 0.24 \\
12.00 & SAND & & 108.0 & 1.0 & 8 & 74.6 & 228 & 0.85 & 0.46 & & \\
13.50 & (Alluvium) & & 121.5 & 0.9 & 5 & – & 257 & 0.81 & 0.43 & 0.07 & 0.24 \\
15.00 & & & 135.0 & 0.9 & 5 & 72.6 & 285 & 0.77 & 0.41 & & \\
16.50 & & & 148.5 & 0.9 & 8 & – & 314 & 0.73 & 0.39 & 0.10 & 0.35 \\
18.00 & & & 162.0 & 0.8 & 8 & – & 342 & 0.69 & 0.37 & 0.10 & 0.37 \\
19.50 & & & 17 To mitigate the effects of boundary conditions in Study Area 2, a steel pipe having a diameter of DN 1500 mm was selected in a model width of 100 m, which corresponds to more than three times the size of the 30 m thick layer (Figure 22). The pipe and soil material parameters are presented in Tables 2 and 5. In the finite element mesh, 9806 triangular elements with 15 nodes each were used, resulting in an average element size of 0.82 m in the model. The boundary conditions shown in Figure 22 were applied. According to the analysis results (Figure 23a) obtained using the seismic input record provided in Figure 17a, with the excess pore water pressure ratio, \(\mathrm{Ru}=1\), liquefaction occurred at a depth of 3.2 m below the surface. The upper layer within the first 3 m is a fill layer composed of sandy clay with a relative density of 58% \(\mathrm{D}_{\mathrm{R}}\). Liquefaction effects are more pronounced in the underlying layer with a relative density of 38% \(\mathrm{D}_{\mathrm{R}}\). Displacements due to liquefaction reached 1.0 m at a distance of 10 m from the pipe and vertical displacements in the pipe were calculated as 0.27 m (Figure 23b). The settlement at the section where the pipe was located was reduced by up to 0.70 m due to the uplift effect in the pipe. Therefore, the excess pore water pressure caused by the presence of the pipe reduced the settlement occurring in the soil. Between 60 and 70 s, the settlement movement of the pipe ceased, and then it continued to settle again (Figure 23b). The total vertical displacements after the earthquake motion are shown in Figure 24.  
In the analyses, the \(\mathrm{Ru}\) value reached 1 and liquefaction occurred in the alluvial unit with a relative density of 38% \(\mathrm{D}_{\mathrm{R}}\) beneath the 3 m thick layer of sandy clay/silty sand (artificial fill), with SPT-N = 16 and \(\mathrm{D}_{\mathrm{R}}=58\%\) at the surface. A thin denser soil layer at the surface (artificial fill) and the underlying 27 m thick alluvium layer contributed to the occurrence of a relatively large settlement. Therefore, the soil profile constrained the uplift of the pipe, giving way to settlement in the pipe along with the soil. In the photograph  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **PM4 Sand** & & & **HSS Model** & \\ \hline \(\mathrm{D}_{\mathrm{R}}\) & \%58 & \%38 & \(\mathrm{D}_{\mathrm{R}}  
of Ataturk Boulevard taken one year after the earthquake, as shown in Figure 10, it is noted that settlement and rupture occurred instead of uplift in the sewer manhole.