PSI - Issue 60

Dhanesh N. et al. / Procedia Structural Integrity 60 (2024) 456–470 Dhanesh et al. / StructuralIntegrity Procedia 00 (2019) 000 – 000

463

8

700

600

500

400

300

200 True Stress (MPa)

100

0

0.000 0.025 0.050 0.075 0.100 0.125 0.150 0.175 0.200 0.225

True Strain

Fig. 7. True stress-true strain curve (API 5L Gr. X60)

Table 3. Properties of native soil

Item

Description

Density (kg/m 3 )

2100

Modulus of elasticity (MPa)

7.5 0.3 33⁰

Poisson’s ratio

Angle of internal friction

Cohesion (kPa)

20

3.4. Loads and Boundary Conditions

3.4.1. Gravity Loads The load due to the self-weight of native soil and embankment is activated during the analysis. The soil mass above the pipeline induces external pressure over the pipeline. 3.4.2. Internal Pressure and Pressure Cycles Internal pressure at the time of the ILI survey, i.e., 14 kg /cm 2 has been applied to the inner surface of the entire pipeline during the denting application step. The same has been removed at the end of the road activation step. During the plastic strain and collapse check, respective internal pressure is applied to the pipeline. The pressure ranges identified in the histogram of the observed pressure cycle are applied during the fatigue verification 3.4.3. Vehicular Loads Since the identified dent is located below the 10-lane Expressway, the effect of vehicular loads is considered. For the present study, the vehicular loads are taken as per IRC:6 (2017). It specifies the vehicular load class and combinations that need to be considered for different types of roads based on the number of lanes and the importance of the road. Even though the present road under study is 5-lane on one way (smaller width of 26 m), as per Table 6 of IRC:6 (2017) it will fall under the 6-lane category (road width between 20.1 m and 23.6 m). Hence for the present study, the following vehicular load combinations are considered as per Table 6A of IRC:6 (2017). Fig.8 shows four vehicular combinations with IRC class A and IRC Class 70R loadings, the details of the same are