Table 4 - uploaded by Matthew Hughes
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... the liquefied areas, the factor of safety was defined based on the severity of manifested liquefaction in the field, as summarized in Table 4. Since triggering of liquefaction yields by definition FS = 1.0, traces of liquefaction, low to moderate liquefaction and moderate to severe liquefaction were given FS values of 0.9, 0.75 and 0.50 respectively. ...
Citations
... Water supply and wastewater pipes are generally buried underground, and they are vulnerable to shaking related ground damage in the form of ground displacement/strain, liquefaction and lateral spreading. During the Canterbury Earthquake Sequence (CES) between 2010-2011, buried infrastructure sustained severe damage [36]. CES provided a wealth of information on ground motions experienced and network damage data to quantify ground damage and to establish fragility functions (in terms of repair rate or break rate per unit length) for buried pipes (e.g. ...
Water networks are vulnerable to earthquakes and failures of network components can result in a lack of availability of services, sometimes leading to relocation of the community. In New Zealand, there are statutory requirements for the water network providers to address the resilience of infrastructure assets. This is done by identifying and managing risks related to natural hazards and planning for appropriate financial provision to manage those risks. In addition to this, the impact from the Canterbury region earthquakes has accelerated the need for understanding the potential risk to critical infrastructure networks to minimise socio-economic impact. As such, there is a need for developing pragmatic approaches to deliver appropriate hazard and risk information to the stakeholders. Within the context of improving resilience for water networks, this study presents a transparent and staged approach to risk assessment by adopting three significant steps: (i) to define an earthquake hazard scenario for which the impact needs to be assessed and managed; (ii) to identify vulnerable parts of the network components; and (iii) to estimate likely outage time of services in the areas of interest. The above process is illustrated through a case study with water supply and wastewater networks of Rotorua Lakes Council by estimating ground motion intensities, damage identification and outage modelling affected by number of crews and preferred repair strategies. This case study sets an example by which other councils and/or water network managers could undertake risk assessment studies underpinned by science models and develop resilience management plans.
... Over the years, some of the most substantial, and costly damages to the early slopes and the foundation of structures has been due to liquefaction of sands during earthquakes [8,9]; hence, it is imperative to take countermeasures against liquefaction and suggest an approach to combat it such that while the soil liquefies, the damage is minimum [4,10]. ...
The uplift effect induced by soil liquefaction on buried pipelines that are critical to the serviceability of buildings, including potable water, natural gas, and sewage pipelines, was experimentally investigated. A full‐scale physical model of pipelines buried in liquefiable ground comprising distribution mains and service lines that connect distribution mains and buildings was built. Shaking table tests were conducted on this model with actual earthquake records utilized as the input motions. The performance of gravel as pipe ditch backfill for mitigating the liquefaction‐induced uplift was also evaluated. During the tests, accelerometers and piezometers were installed in free‐field (FF) soil and around the pipelines to reveal the pipeline–soil interaction and the soil liquefaction development. Wire potentiometers were also utilized to monitor any uplift or subsidence of the pipelines. Results indicate that the distribution mains for natural gas and sewage experienced an uplift during liquefaction of ground specimen. The excess porewater pressure buildup level around the uplifted pipelines was generally lower than that in FF soil and was even lower on top of the pipeline circumference, which may be attributed to the pipeline–soil interaction. Furthermore, the practicability of an existing simplified model for anti‐uplift stability assessment and its corresponding uplift force estimation were examined based on aforementioned observations. The findings indicate that the uplift effect for large‐diameter pipelines may be underestimated by simply using this simplified model. This research can be used as a reference for the seismic design of buried pipelines, which is beneficial for disaster prevention and mitigation.
