# 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  
Atatifrk Boulevard is located along the coast of Iskenderun (Figure 2). While the seaside of this Boulevard is designated for parks and social areas, the opposite side is occupied by buildings. According to the Preliminary Assessment Report for the Kahramanmaras-Pazarcik Mw = 7.7 and Elbistan Mw = 7.6 earthquakes on 6 February 2023, the majority of the buildings in this location were found to have suffered moderate to severe damage. This report provides images and locations of damaged buildings in the Cay Neighborhood [58]. The effects of liquefaction have been observed both in buildings and buried structures along the coastline. According to the microzonation report [60], most of the Iskenderun coastline consists of alluvial units, as shown in Figure 12(a). Figure 12(b) displays the MASW Vs30 map of Study Area 2 along the Iskenderun coastline, as well as the location of borehole ISK-259. The soil profile according to the boreholes drilled in the area are given in Section 1 in Figure 12(d). The orientation of the section is shown in Figure 12(b). After the earthquake, liquefaction-induced damage occurred in stormwater and sewage pipelines along Atatifrk Boulevard lying parallel to the coastline, and some pipes were subjected to vertical displacement and consequently became blocked, causing local flooding on the streets. The borehole and geophysical surveys representing Study Area 2 are presented in Figure 13(a). According to the MASW-386 survey, the shear wave velocity is 210 m/s in the top 7 m of the ground, rises to 250 m/s between depths of 7 and 12 m, and becomes 300 m/s below. According to borehole ISK-259 representing this area, the top layer is sandy clay, 3 m thick (58% D\({}_{\text{R}}\)), followed by a layer of gravelly sand, 17 m thick (Figure 13(a)). Borehole ISK 258 in Section 1 in Figure 12(d) indicates that the thickness of the alluvialium is not less than 30 m. Both layers, as particularly indicated by the SPT-N\({}_{30}\) (5-12) results, show liquefaction potential; therefore, they can be considered liquefiable also based on seismic velocities (Figures 12(d) and 13(a)). The variation with depth of the safety factors obtained using relationships derived from [PERSON] and [PERSON] [61] and later updated [53; 54; 62]  
Figure 20: Vertical displacement for DN \(\O\) 1500 mm steel pipe with station 3116 data during earthquake motion (Vs = 870 m/s) in the Pazarcik earthquake (Mw 7.7). is presented in Figure 21b. For local ground class ZE and a probability of exceedance of 10% in 50 years (with a return period of 475 years) along the iskenderun coast, a short-period design spectral acceleration coefficient of SDS = 0.972 was considered for calculating the safety factor (Table 4). Although no information is available on the layer beneath the alluvium, it has been demonstrated in the study by [PERSON] [63] that the bedrock lies at a depth greater than 50 m based on seismic velocities. Therefore, at a depth of 30 m, the presence of an extremely weathered rock (residual soil) layer was assumed (as shown in Table 2). In the analysis, Station 3115 records were used, and a damping ratio of 2% was considered for the liquefied soil layer.