Search inside publication
Geometric and material non-linear wave propagation with the material point method
This paper presents the numerical modelling of one-dimensional wave propagation with the material point method, considering geometric and material non-linearity. Geometrical non-linearity corresponds to the non-linear relation between strain and displacements due to large deformations, whilst material non-linearity is caused by the non-linear relation between stress and strain. In this study, a finite solid column will be used as an example to illustrate the effect of both non-linearities in the overall response.
Proceedings of the 2nd International Conference on the Material Point Method for Modelling Soil-Water-Structure Interaction - MPM 2019 (Cambridge, 8-10 January 2019))
Passive dosing of organic substrates for nitrate-removing bioreactors applied in field margins
Denitrifying bioreactors are dependent on organic matter supply as a substrate for effective NO3 removal. In this study, the difference in removal efficiency and side effects when using different organic matter sources and dosing strategies was tested in two field experiments. The organic matter sources tested were woodchips and ethanol. The effect of woodchips was tested using woodchip-enveloped drains. Ethanol was supplied to a flow-through reactor by passive dosing by diffusion through silicone tubing. The woodchip-enveloped drains showed a removal efficiency of 80% during the first year of application, but this rate decreased during the second and third years of application, coinciding with a decrease in dissolved organic C and an increase in redox potential. The removal efficiency was higher and remained higher over a longer period of time when the drains were installed more deeply. The flow-through reactor with ethanol could lead to a higher removal efficiency (up to 95%) at higher hydraulic retention time (HRT, 0.1 d) than the woodchip-enveloped drains (HRT = 5 d). Passive dosing of organic substrates is simple, needs little maintenance and no energy, and can be performed independent of electricity. A denitrifying bioreactor with a controlled drainage inlet and outlet is a promising setup for optimizing N removal and minimizing side effects.
Modeling mussel bed influence on fine sediment dynamics on a Wadden Sea intertidal flat
Mussel beds are coherent colonies of mussels and are widespread in the Dutch Wadden Sea and the Eastern Scheldt estuary. Mussel beds are known to be an important factor in biogeomorphological processes, primarily because of the influence on fine sediment dynamics. Ongoing research to explore the use of mussels as bio-tools makes predictive modeling desirable. In this study a process-based model of the interaction between a young mussel bed and fine sediment was set up for use in Delft3D-FLOW. The model encompasses the hydraulic roughness of the mussel bed, active capture of suspended sediment by filter feeding and changed properties of sediment inside the mussel bed to account for the presence of biodeposited matter. The mussel bed implementation in Delft3D-FLOW was tested in a Wadden Sea intertidal mudflat model. Two current dominated summer months were simulated. The effects of different patterns, known to occur in young mussel beds, were evaluated. It was concluded that roughness and filtration rate of mussel beds are important factors in mussel bed influence on fine sediment. A combination of active deposition via filtration and slow down of the flow due to increased roughness leads to high net deposition in the mussel bed. In addition, the ability of young mussels to quickly climb on top of deposited material results in rapid trapping of large amounts of fine sediment. In the wakes of the mussel bed deposition is also high because of reduced flow velocities. Patchiness and specifically striped patterns cause mussel beds to experience less sedimentation than uniformly covered beds of the same size.
Microbial induced carbonate precipitation as ground improvement method : bacterial fixation and emperical correlation CaCO3 vs strength
BioGrout is a new in situ soil strengthening technique involving microbial mediated carbonate precipitation. The current research on BioGrout aims to improve understanding of the relevant phenomena in the cementation process and enable up-scaling of the technology to suit commercial applications. This paper describes two aspects: 1) a method for the fixation of bacteria in the sand bed, and 2) the emperical relationship between strength and carbonate content for a specific sand type. This information allows us to design applications in practice and determine economic feasibility.
Environmental friendly technology for biological sand-consolidation of oil and gas well-bore
A technique based on the use of pure enzyme for sand cementation has been studied and seems to hold potential. As the cementation of loose sand by Microbial Carbonate Precipitation (MCP) has been successfully experimented, the MCP has been assessed for purpose of sand control. This paper describes the steps taken in order to come to the proof of concept of this environmental friendly bio-consolidation technology for in-situ cementation of sandy oil formation developed to prevent sand production. The aim of this bio-consolidation is to bond the sand grains together with calcium carbonate in order to provide an additional strength required while preserving as much as possible the sand permeability.
15th international conference on structural and geotechnical engineering (ICSGE15) : advances in construction techniques (Cairo, Egypt, 18-20 December 2018)
The Dutch design guideline basal reinforced piled embankments, and the development and validation of its design methods
This paper presents the 2016-update of the Dutch design guideline for basal reinforced piled embankments. This guideline was developed in full compliance with the Eurocodes, including Eurocode 7 (NEN-EN 1997-1 with its national appendices. The guideline has been published both in Dutch and English. Special attention is given to: (1) The development and validation of the Concentric Arches model. This model is used for the GR design. (2) The model factor and the partial load- and material factors. With a probabilistic study it is shown that the set of these factors match the reliability requirements of Eurocode 0. In addition, this safety approach has been compared with the German safety approach.
Grootschalig actief grondwaterpeilbeheer in bebouwd gebied : fase 2 : consultatie
Dit rapport is een vervolg op het onderzoeksrapport ‘Grootschalig actief grondwaterpeilbeheer in stedelijk gebied – Fase 1: Bureaustudie’ (Deltares, Wareco en Fugro, 2017). Actief grondwaterpeilbeheer is een gerichte inspanning om een gewenst grondwaterpeil te realiseren, met een drainage-infiltratieleiding in verbinding met het oppervlaktewater. De maatregel helpt grondwaterfluctuaties te beperken, en daaruit voortvloeiende schades door grondwateroverlast en -onderlast. Grondwaterfluctuaties zullen naar verwachting toenemen onder invloed van klimaatverandering, en daarom draagt actief grondwaterpeilbeheer bij aan een klimaatbestendige stedelijke leefomgeving.
Large-scale experiments into the tsunamigenic potential of different iceberg calving mechanisms
In the Delta Basin at Deltares Delft physical model tests were performed to assess the magnitude of tsunamis that can be generated by calving icebergs. Global warming causes increased risks of iceberg calving, which can generate large tsunamis endangering human beings and coastal infrastructure. Such iceberg-tsunamis have reached amplitudes of 50m and destroyed harbours. The model tests have provided insight into the physical processes and the magnitude of generated tsunamis. The model tests were part of the European HYDRALAB+ project that is focussed on climate adaptation.