Seismic Performance Evaluation of Buried Pipelines
Buried pipelines are the major component of many lifeline engineering systems, such as water supply systems, gas supply systems and heating supply systems. During past earthquakes, buried pipelines suffered serious damages and some of them cause serious s
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Seismic Performance Evaluation of Buried Pipelines
4.1 Seismic Damage of Buried Pipelines 4.1.1 Pipeline Damage in Past Earthquakes Buried pipelines are the major component of many lifeline engineering systems, such as water supply systems, gas supply systems and heating supply systems. During past earthquakes, buried pipelines suffered serious damages and some of them cause serious secondary disasters. Seismic investigation on buried pipelines originated from the early of 1920’s. After the Kanto earthquake, Japan, in 1923, the buried pipelines in Tokyo were investigated in detail. The investigation indicated that over 80% joints, were damaged, about 71% of which were leaky. Afterward, the damages of lifeline engineering systems (especially for the buried pipelines) during earthquakes which is close to modern cities are investigated in detail. For example, after the San Fernando earthquake, American in 1971, the buried pipelines of Los Angeles city were investigated widely (Wang, Sun, & Shen, 1985). The investigation indicated that 856 breaks appeared on water pipelines and the average damage ratio of water cast iron pipelines was 0.95/km in the area where the seismic intensity was between VIII and IX. Meanwhile, 450 breaks appeared on gas pipelines of which were mostly 50–100 mm welded steel pipes and the damage ratio was 0.12/km. On July 28, 1976, a strong earthquake with a magnitude of 7.8 attacked Tangshan, China. The seismic intensity of epicenter was as high as XI. Beijing and Tianjin, the capital and an important municipality of China, were also influenced by this strong earthquake. The earthquake seismic of Tianjin was VII–IX. Table 4.1 illustrates the seismic investigation of water supply pipelines in different areas with different site conditions (Liu, 1986). In 1995, a strong earthquake with a magnitude of 7.2 happened in Kobe, Japan. Like other strong earthquakes, the buried pipelines suffered serious damages. Based on these historic investigations, in 2001, the American Lifeline Engineering Associate summarized the earthquake damages of buried pipelines systemically (ALA, 2001). © Shanghai Scientific and Technical Publishers 2021 J. Li and W. Liu, Lifeline Engineering Systems, https://doi.org/10.1007/978-981-15-9101-3_4
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4 Seismic Performance Evaluation of Buried Pipelines
Table 4.1 Damage ratio of buried pipelines in different areas subjected to the Tangshan earthquake Area
Seismic Intensity
Soil classification
Pipe diameter (mm)
Pipe length (km)
Number of damages
Tianjin
VII–VIII
III
75–1000
870.0
Tanggu
VIII
III
75–600
Average damage ratio (/km)
161
0.18
79.50
332
4.18
Hangu
IX
III
–
–
–
Tangshan
X–XI
II
75–600
111.00
446
10.00 4.00
4.1.2 Damage Characteristics of Buried Pipelines The major effects of earthquake on buried pipelines are permanent ground deformation and ground motion. The former includes fault rupture, soil liquefaction, landslip and surface collapse. In the area where permanent ground deformation covers, the damage ratio of buried pipeline
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