# 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 3116 Station Data for Study Area 1
In the Sarneki Region, the shear wave velocity values fall within the dark blue zone in Figure 13c, i.e., they are in the range of 250 m/s to 350 m/s, providing more favorable conditions for liquefaction. According to the information provided by HATSU (Hatay Water Authority), the pipeline between the treatment plant and Isdemir steel manufacturing plant did not suffer significant liquefaction damage due to the earthquake. The analysis results also demonstrate low uplift behavior, ranging from 0.035 m to 0.075 m, indicating no significant liquefaction-induced damage in this area. The main reason for this is the proximity of the bedrock to the surface along the pipeline. The modeling in Study Area 1 demonstrated the impact of seismic records obtained from the rock at station 3116 on underground pipe displacement. Based on the geophysical data of station 3116 (Vs30 = 870 m/s), analyses were conducted under the assumption that a 1 m thick layer of rock underlay the conglomerate layer despite the lack of information on the presence of solid rock below the alluvium. In Study Area 1, the seismic records obtained from stations 3115 and 3116, as well as the variation in bedrock depth, significantly influenced the behavior of the pipe. The uplift of the pipe decreased by 70% when the bedrock seismic record from station 3116 was used, as shown in Figures 16d and 19c. According to the results of the analysis, it can be concluded that in regions where the bedrock layers are close to the surface, the soil exhibits smaller settlement and, consequently, smaller pipe uplift. As shown in Figure 16c, the displacement around the pipe decreased by 0.30 m in total settlement when the model width was expanded to 120 m. This resulted in greater uplift in the pipe (Figure 16d). There was no downward deformation during the uplift of the pipe. However, at a distance of approximately 10 m from the pipe, vertical displacements (settlements) on the surface were at about 0.15 m. As shown in Figure 19c, in the analysis conducted using the seismic record from station 3116 and assuming that the bedrock was close to the surface, lower peak ground accelerations (PGA) resulted in smaller uplift. The significant difference between soil conditions at stations 3115 and 3116, characterized by different shear wave velocities (Vs30 = 424 m/s and Vs30 = 870 m/s, respectively), resulted in different seismic effects on the corresponding units. As a result, areas analyzed using the seismic record from station 3115 were observed to experience displacements exceeding 1.7 m, as shown in Figure 17b. On the other hand displacements of up to 0.56 m were calculated when the seismic record from station 3116 was used in areas where the bedrock was close to the surface (Figure 20). These analyses demonstrate the importance of determining the model width to minimize the impact of model boundaries and boundary conditions on the behavior of the buried pipe. However, increasing the model width also significantly increases analysis durations. Therefore, in numerical analyses, model boundaries should be selected in such a way that they do not affect the behavior of the buried structure. Figure 19: (**a**) Station 3116 E (PGA = 160.8 cm/s\({}^{2}\) and Vs30 = 870 m/s) earthquake motion during the Pazarcı earthquake (Mw 7.7); (**b**) Ru value for DN 1500 steel pipe H = 2.50 m depth from far field; (**c**) vertical displacement for DN 1500 steel pipe H = 1D, H = 1.2D, H = 1.5D.