Seismic resilience of extra-large LNG tank built on liquefiable soil deposit capturing soil-pile-structure interaction

Abstract

Assessment of seismic resilience of critical infrastructure such as liquefied natural gas (LNG) storage tanks, is essential to ensure availability and security of services during and after occurrence of large earthquakes. In many projects, it is preferred to build energy storage facilities in coastal areas for the ease of sea transportation, where weak soils such as soft clay and loose sand with liquefaction potential may be present. In this study, three-dimensional finite element model is implemented to examine the seismic response of a 160,000 m3 full containment LNG tank supported by 289 reinforced concrete piles constructed on liquefiable soil overlaying the soft clay deposit. The seismic soil-structure interaction analysis was conducted through direct method in the time domain subjected to the 1999 Chi-Chi and the 1968 Hachinohe earthquakes, scaled to Safe Shutdown Earthquake hazard level for design of LNG tanks. The analyses considered different thicknesses of the liquified soil deposit varying from zero (no liquefaction) to 15 m measured from the ground surface. The key design parameters inspected for the LNG tank include the acceleration profile for both inner and outer tanks, the axial, hoop and shear forces as well as the von Mises stresses in the inner tank wall containing the LNG, in addition to the pile response in terms of lateral displacements, shear forces and bending moments. The results show that the seismic forces generated in the superstructure decreased with increasing the liquefied soil depth. In particular, the von Mises stresses in the inner steel tank exceeded the yield stress for non-liquefied soil deposit, and the elastic–plastic buckling was initiated in the upper section of the tank where plastic deformations were detected as a result of excessive von Mises stresses. However, when soil liquefaction occurred, although von Mises stresses in the inner tank shell remained below the yield limit, localised stress concentrations were observed in the lower section of the tank near the base, increasing the risk of the elephant foot buckling. The lateral displacements, shear forces and bending moments in the piles increased with increasing depth of the liquefied soil. Indeed, increasing the pile lateral displacement amplified the bending moment at the pile head, thus resulting in increases in the pile bending moments especially when the liquefied soil depth exceeded one third of the entire soil deposit. In particular, the bending moment at the pile head exceeded the yield moment capacity of the pile and subsequent plastic hinges were formed. Moreover, when the thickness of the liquefied soil was more than half of the entire soil depth, the mobilised bending moments in the piles exceed the ultimate moment capacity of the pile and thus total failure of the piles were observed. In addition, in the absence of liquefied soil layer, the inertial interaction had a dominant impact on the pile response in this study. However, with increasing the thickness of the liquefied layer, further loads were developed in the piles due to amplified kinematic interaction, while the inertial interaction-induced loads decreased.

Monitoring Scheme of Liquified Natural Gas External Tank Using Air–Space–Land Integration Multisource Remote Sensing

“…The research related to the safety monitoring technology of large LNG storage tanks includes the real-time monitoring of temperature, strain, sedimentation, displacement, and deformation of large storage tanks. (2,3,5) Therefore, we monitored the integrity of the LNG external tank through air-space-land integration multisource remote sensing monitoring technology, integrating total station control measurement, LiDAR measurement, UAV photogrammetry, infrared thermal camera measurement identification, and InSAR settlement monitoring (Fig. 3).…”

“…(1) With the rapid development of China's economy, the trend in LNG storage tanks is to expand the scale of production, large capacity, and higher demands on individual parameters. (2) As the size of the storage tanks increases, their potential risks also increase, and the chances of leakage and explosion accidents likewise gradually increase. Furthermore, LNG storage tanks can be overly deformed during the use of the tank wall for various reasons, resulting in its inability to play a protective role.…”

Nonlinear behaviour of liquefied natural gas tanks with different seismic isolation systems

“…Although the base shear force, overturning moment and acceleration spectra of the tank were significantly reduced, the displacement of the tank posed a danger to the piping system connected to the tank. Sharari et al [30] examined a 160,000 m 3 full containment LNG tank considering the soil structure and fluid-structure interactions while assessing the impacts of the depth of soil liquefaction on the performance of different components of the system. According to the nonlinear time history results, the seismic forces on the inner steel and outer reinforced concrete tank walls decreased as the liquefaction depth increased.…”

Preface to special issue on modelling and assessment of soil-structure interaction effects on the dynamics of structures

“…The numerical model is firstly calibrated and then used to conduct a parametric investigation by varying the monopile length and diameter, the soil friction angle, and the liquefaction depths. Sharari et al (2022) study the effect of the depth of liquefiable soil deposits on the seismic response of liquid natural gas tanks supported by pile foundation through three-dimensional FE analysis. SSI effects on buildings are studied by Zhang and Far (2022), who investigate the seismic performance of frame-core tube structures, which is a structural typology generally used for high-rise buildings, through FE modelling, accounting for SSI effects and considering different heights of the building.…”