Eidsvig U.M.K.,NGI Inc |
Kristensen K.,NGI Inc |
Vangelsten B.V.,NGI Inc
Natural Hazards and Earth System Sciences | Year: 2017
This paper proposes a model for assessing the risk posed by natural hazards to infrastructures, with a focus on the indirect losses and loss of stability for the population relying on the infrastructure. The model prescribes a three-level analysis with increasing level of detail, moving from qualitative to quantitative analysis. The focus is on a methodology for semi-quantitative analyses to be performed at the second level. The purpose of this type of analysis is to perform a screening of the scenarios of natural hazards threatening the infrastructures, identifying the most critical scenarios and investigating the need for further analyses (third level). The proposed semi-quantitative methodology considers the frequency of the natural hazard, different aspects of vulnerability, including the physical vulnerability of the infrastructure itself, and the societal dependency on the infrastructure. An indicator-based approach is applied, ranking the indicators on a relative scale according to pre-defined ranking criteria. The proposed indicators, which characterise conditions that influence the probability of an infrastructure malfunctioning caused by a natural event, are defined as (1) robustness and buffer capacity, (2) level of protection, (3) quality/level of maintenance and renewal, (4) adaptability and quality of operational procedures and (5) transparency/complexity/degree of coupling. Further indicators describe conditions influencing the socio-economic consequences of the infrastructure malfunctioning, such as (1) redundancy and/or substitution, (2) cascading effects and dependencies, (3) preparedness and (4) early warning, emergency response and measures. The aggregated risk estimate is a combination of the semi-quantitative vulnerability indicators, as well as quantitative estimates of the frequency of the natural hazard, the potential duration of the infrastructure malfunctioning (e.g. depending on the required restoration effort) and the number of users of the infrastructure.
Case studies for two Norwegian municipalities are presented for demonstration purposes, where risk posed by adverse weather and natural hazards to primary road, water supply and power networks is assessed. The application examples show that the proposed model provides a useful tool for screening of potential undesirable events, contributing to a targeted reduction of the risk. © The Author(s) 2017.
Pal S.,Gautam Buddha University |
Kaynia A.M.,NGI Inc |
Bhasin R.K.,Rock and Foundation Engineering |
Paul D.K.,Indian Institute of Technology Roorkee
Rock Mechanics and Rock Engineering | Year: 2012
Stability analysis of Surabhi landslide in the Dehradun and Tehri districts of Uttaranchal located in Mussoorie India, has been simulated numerically using the distinct element method focusing on the weak zones (fracture). This is an active landslide on the main road toward the town centre, which was triggered after rainfall in July-August 1998. Understanding the behaviour of this landslide will be helpful for planning and implementing mitigation measures. The first stage of the study includes the total area of the landslide. The area identified as the zone of detachment is considered the most vulnerable part of the landslide. Ingress of water and increased pore pressures result in reduced mobilized effective frictional resistance, causing the top layer of the zone of detachment to start moving. The corresponding total volume of rock mass that is potentially unstable is estimated to 11.58 million m3. The second stage of this study includes a 2D model focussing only on the zone of detachment. The result of the analyses including both static and dynamic loading indicates that most of the total displacement observed in the slide model is due to the zone of detachment. The discontinuum modelling in the present study gives reasonable agreement with actual observations and has improved understanding of the stability of the slide slope. © 2011 Springer-Verlag.
News Article | November 16, 2016
AMBLER, Pa., Nov. 16, 2016 /PRNewswire/ -- Radius Global Solutions LLC ("RGS"), a global technology-enabled provider of end-to-end accounts receivable and customer relationship management solutions, announced today that it has merged with Northland Group Inc. ("NGI"), a Minneapolis,...
Lovholt F.,NGI Inc |
Madshus C.,NGI Inc |
Noren-Cosgriff K.,NGI Inc
Noise Control Engineering Journal | Year: 2011
Low frequency sound, in addition to the effects of audible sound, contributes to human annoyance and building damage by inducing building vibration. This involves whole body vibration sensing of humans, and therefore frequencies down to a few Hz become important. Here, the results of a study of low frequency sound and its generation of building vibration and induced indoor sound is presented. The study is conducted by combining both full scale field tests and numerical simulations. It is shown that the low frequency sound interaction with the fundamental frequencies of the building components combined with air leaks in the building envelope are the main factors that govern transmission of sound into the building. Furthermore, radiation from vibrating ceiling and walls seems to be the dominant source of the low frequency indoor sound, and floor vibration is acoustically driven by the indoor sound pressure in the room. Due to the low frequencies in question, tools to predict sound and vibration, and design mitigation measures at low frequencies noise and vibration in building structures are virtually non-existent. To this end, a finite element model combining acoustic wave propagation and structural dynamics presented in this paper provides a first step. Using this model, a number of countermeasures has been tested and some proven effective in this low frequency range. © 2011 Institute of Noise Control Engineering.
Vanneste M.,NGI Inc
74th EAGE Conference and Exhibition Incorporating SPE EUROPEC 2012 | Year: 2012
In this contribution, we review the current practice in submarine landslides research, in which a multidisciplinary approach is essential. These include, but are not limited to, geophysics, geology, geochemistry, geotechnics and geomechanics, slope stability simulations, landslide dynamics, consequence analysis (e.g., tsunami, impact, risk assessment). Following a brief introduction on the - typical - three-phase landslide development, we address a number of issues at stake (e.g., gas, hydrate, excess pore pressure) that should be addressed in more detail in future research activities within this field. These include in situ measurements, but also the advanced use of geophysical methods to derive soil properties in the shallow sub-surface. Finally, we highlight activities conducted to develop the Finneidfjord area (northern Norway) as a natural field laboratory for submarine landslide investigations. When it comes to smaller-scale landslides, high lateral and vertical resolution is paramount to understand such landslides, which still can have devastating consequences.
Jostad H.P.,NGI Inc |
Andersen K.H.,NGI Inc
Frontiers in Offshore Geotechnics III - Proceedings of the 3rd International Symposium on Frontiers in Offshore Geotechnics, ISFOG 2015 | Year: 2015
The paper compares different calculation methods for undrained holding capacity of suction anchors in clay. Pure vertical and horizontal holding capacity of short, medium and deep closed suction anchors in both clay with linearly and constant isotropic undrained shear strength profiles are considered. Results obtained by3Dfinite element analyses are compared with a semi-empirical equation for piles and more simplified solutions where the 3D effect is accounted for by side shear. For these idealized failure mechanisms the shear strength on the sides needs to be multiplied by a correction factor. Factors that results in the same capacity as for the full 3D. © 2015 Taylor & Francis Group, London.
Lovholt F.,NGI Inc |
Kuhn D.,NORSAR |
Bungum H.,NORSAR |
Harbitz C.B.,NGI Inc |
Glimsdal S.,NGI Inc
Journal of Geophysical Research: Solid Earth | Year: 2012
Eastern Indonesia and the southern Philippines comprise a huge and seismically highly active region that has received less than the deserved attention in tsunami research compared with the surrounding areas exposed to the major subduction zones. In an effort to redress the balance the tsunami hazard in this region is studied by establishing a tsunami event database which, in combination with seismological and tectonic information from the region, has allowed us to define and justify a number of 'credible worst-case' tsunami scenarios. These scenarios have been used in numerical simulations of tsunami generation and propagation to study maximum water level along potentially affected shorelines. The scenarios have in turn been combined to provide regional tsunami hazard maps. In many cases the simulations indicate that the maximum water level may exceed 10 m locally and even reach above 20 m in the vicinity of the source, which is of the same order as what is forecasted along the Sumatra and Java trenches for comparable return periods. For sections of coastlines close to a source, a tsunami may strike only a few minutes after it is generated, providing little time for warning. Moreover, several of the affected areas are highly populated and are therefore also high risk areas. The combination of high maximum water levels, short warning times, dense populations, and relatively short return periods suggests strongly that the tsunami hazard and risk in these regions are alarmingly high. © 2012. American Geophysical Union. All Rights Reserved.
Meyer V.,NGI Inc |
Langford T.,NGI Inc |
White D.J.,University of Western Australia
Geotechnique | Year: 2016
Pipelines laid on the seabed are subjected to loads that may cause unacceptable displacements. On fine-grained soils, the capacity of a pipeline to resist these loads is affected by the pipe embedment and any excess pore pressures remaining in the surrounding soil from the laying process. This paper presents results from model tests, performed at near to full scale, investigating the embedment response and the subsequent pore pressure equalisation of a pipeline on a high plasticity marine clay. Existing models for the penetration and dissipation processes are compared with the experimental data. Conventional undrained bearing capacity theory, making minor allowances for strain rate and softening effects, shows good agreement with the observed penetration response. Dissipation solutions based on elastic and elasto-plastic soil models capture the general shape of the pore pressure response. The operative coefficient of consolidation varies between tests, spanning the range between the compression and recompression values observed in oedometer tests. The observations validate the theoretical solutions for penetration resistance, and highlight the uncertainty that must be considered in estimating equalisation times. © 2016, ICE Publishing. All rights reserved.
NGI Inc | Date: 2013-12-06
Products of metal for the adjustment, stabilization and vibration: reduction of all kinds of machines and equipment, namely, frames, racks, nuts, washers, threaded bushings, bolts, plates, pipes and tubes of metal. Parts of machines, namely, products of metal for the adjustment, stabilization and vibration reduction of all kinds of: machines and equipment, namely, stainless steel machine feet, and legs, machinery mounts and pads, levelling pads, frames and racks, welding and foot plates, bases. Rubber and plastic products for the adjustment, stabilization and vibration reduction of all kinds of machines and equipment; namely, machine feet and legs, packing, stopping and insulating materials; flexible pipes, not of metal. Repair; installation services; the aforementioned services in connection with products for the adjustment, stabilization, and vibration reduction of all kinds of machines and equipment.