Bayesian optimization for CPT-based prediction of impact pile drivability

Pile drivability predictions require information on the pile geometry, impact hammer, and the soil resistance to driving (SRD). Current SRD prediction methods are based on databases of long slender piles from the oil and gas industry and new, robust, and adaptable methods are required to predict SRD for current offshore pile geometries. This paper describes an optimization framework to update uncertain model parameters in existing axial static design methods to calibrate SRD. The approach is demonstrated using a case study from a German offshore wind site. The optimization process is undertaken using a robust Bayesian approach to dynamically update uncertain variables during driving to improve simulations. The existing method is shown to perform well for piles with geometries that reflect the underlying database such that only minimal optimization is required. For larger diameter piles, relative to the prior best estimate, optimized results are shown to provide significant improvements in the mean calculations and associated variance of pile drivability as more data is acquired. The optimized parameters can be used to predict SRD for similar piles in analogous ground conditions. The demonstrated framework is adaptable and can be used to develop site-specific calibrations and advance new SRD methods where large pile driving data sets are available

The Lancet Countdown: tracking progress on health and climate change

The Lancet Countdown: tracking progress on health and climate change is an international, multidisciplinary research collaboration between academic institutions and practitioners across the world. It follows on from the work of the 2015 Lancet Commission, which concluded that the response to climate change could be “the greatest global health opportunity of the 21st century”. The Lancet Countdown aims to track the health impacts of climate hazards; health resilience and adaptation; health co-benefits of climate change mitigation; economics and finance; and political and broader engagement. These focus areas form the five thematic working groups of the Lancet Countdown and represent different aspects of the complex association between health and climate change. These thematic groups will provide indicators for a global overview of health and climate change; national case studies highlighting countries leading the way or going against the trend; and engagement with a range of stakeholders. The Lancet Countdown ultimately aims to report annually on a series of indicators across these five working groups. This paper outlines the potential indicators and indicator domains to be tracked by the collaboration, with suggestions on the methodologies and datasets available to achieve this end. The proposed indicator domains require further refinement, and mark the beginning of an ongoing consultation process—from November, 2016 to early 2017—to develop these domains, identify key areas not currently covered, and change indicators where necessary. This collaboration will actively seek to engage with existing monitoring processes, such as the UN Sustainable Development Goals and WHO's climate and health country profiles. The indicators will also evolve over time through ongoing collaboration with experts and a range of stakeholders, and be dependent on the emergence of new evidence and knowledge. During the course of its work, the Lancet Countdown will adopt a collaborative and iterative process, which aims to complement existing initiatives, welcome engagement with new partners, and be open to developing new research projects on health and climate change

Response of armour rock-scour protection to earthquake-induced liquefaction for offshore wind applications

Offshore wind is an abundant and indispensable source of renewable energy which recently has seen rapid expansion in East Asia and North America. Soil profiles in East Asia can typically include shallow layers of loose, liquefiable sand overlying competent soil strata which may impact the stability of both the foundation and the scour protection during an earthquake. When employed, scour protection is key to the stability and long-term operation of the wind turbine, and typically consists of graded rocks placed around the foundation to prevent the localised erosion of the soil and any degradation in the foundation behaviour that scour may cause. However, there is limited data currently available on the behaviour of scour protection on liquefiable soils. This paper presents the results of a saturated dynamic centrifuge test that explores the behaviour of large armour rock scour protection on liquefiable soils during seismic events. The use of a combination of sensors and particle image velocimetry enable the recording of rock settlements, accelerations and in particular interstitial pore pressure. The results show that the rock protection prevents the soil beneath it from reaching full liquefaction, but nevertheless, sustains significant settlement during small to medium input motions. The results form the basis for further research into the behaviour of rock protection under dynamic cyclic loading to ensure robust design in seismically active zones

Bayesian optimisation for CPT-based prediction of impact pile driveability

No abstract available