It is well accepted that an urban region's seismic resilience is directly related to the seismic resilience of the local water systems. Pipelines having low earthquake resistance generally include old pipes and those susceptible to corrosion. The seismic vulnerability of the water transmission pipelines can be evaluated along with the geologic hazards such as landslides, liquefaction, fault movement, etc. In this study, GIS-based analyses are implemented for one of Tehran's main water transmission pipelines, which transfer Mamloo Dam water to Tehran's southern regions, by considering the four most probable earthquake scenarios to evaluate post-earthquake serviceability of the studied pipeline. Transient Ground Deformation (TGD) due to seismic wave propagation, and also Permanent Ground Deformation (PGD), which may result in liquefaction (lateral spreading, and ground settlement) and landslide, are regarded as destructive earthquake effects on the water transmission pipelines. A restoration curve is also developed for the worst scenario to investigate the adequate post-earthquake water supply throughout the service area and ensure rapid system recovery. Results show that the water serviceability index regarding the worst earthquake scenario (Rey fault activated) is 28%, which means that more than 72% of the study area's population will experience severe disruption of water availability in a potential earthquake.
Earthquakes have caused significant damage to civil engineering structures worldwide due to inadequate lateral load capacity and excessive deformation of pile foundations supporting these structures. The seismic performance of pile foundations interacting with unsaturated soils could be affected by changes in matric suction due to the moisture content variation induced by seasonal weather changes or water table fluctuations. Hence, the main objective of this study is to investigate the effects of unsaturated soil conditions on the seismic response of a pile-soil system in silty clay soils. This study utilized a stand-alone finite element computer code called DYPAC (Dynamic Piles Analysis Code) developed using the Beams on Nonlinear Winkler Foundation (BNWF) approach. Free field soil displacements and p-y curve parameters, inputs needed for DYPAC analyses, were updated based on the soil suction variations. This study found that soil suction can significantly influence the seismic performance of piles interacting with unsaturated silty clay soils, especially as the soil becomes drier in the transition zone. The best seismic performance of the pile, which is the minimum lateral pile displacement, happened in the transition zone between fully saturated and nearly dry conditions.
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