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- Abbaszadeh Shahri, Abbas, et al.
(författare)
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Landslide susceptibility hazard map in southwest Sweden using artificial neural network
- 2019
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Ingår i: Catena (Cremlingen. Print). - : ELSEVIER. - 0341-8162 .- 1872-6887. ; 183
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Tidskriftsartikel (refereegranskat)abstract
- Landslides as major geo-hazards in Sweden adversely impact on nearby environments and socio-economics. In this paper, a landslide susceptibility map using a proposed subdivision approach for a large area in southwest Sweden has been produced. The map has been generated by means of an artificial neural network (ANN) model developed using fourteen causative factors extracted from topographic and geomorphologic, geological, land use, hydrology and hydrogeology characteristics. The landslide inventory map includes 242 events identified from different validated resources and interpreted aerial photographs. The weights of the causative factors employed were analyzed and verified using accepted mathematical criteria, sensitivity analysis, previous studies, and actual landslides. The high accuracy achieved using the ANN model demonstrates a consistent criterion for future landslide susceptibility zonation. Comparisons with earlier susceptibility assessments in the area show the model to be a cost-effective and potentially vital tool for urban planners in developing cities and municipalities.
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| 4. |
- Beijer Lundberg, Anders, et al.
(författare)
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Risk management and risk acceptance regarding the stability of slopes: Case study
- 2021
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Konferensbidrag (refereegranskat)abstract
- Most earthworks result in an alteration of the stress state in the ground, either throughthe excavation of soil or the placement of surcharge on the ground surface. These stress changeshave the potential to cause a slope collapse or failure, often with large consequences for theconstruction project or the immediate environment. Slope stability calculations are thereforefrequently carried out for various load and excavation stages in the design phase to reduce therisk in the construction phase. Nevertheless, slope collapses sometimes occur, both small oneswith minor consequences, as well as larger ones with significant consequences for society. In thecurrent paper, a case history of a slope from Scandinavia is examined to assess how the risk ofslope stability was managed and allocated among the various agents, and how the slide coulddevelop. Was the risk acceptable for society on an aggregate level? The soil conditions and theconstruction process for the case studies are elaborated in detail with respect to the riskmanagement principles in ISO 31000 and the recently published guidelines from the SwedishGeotechnical Society. The risk acceptance and the concept of the risk owner, i.e. the entity thatowns the specific risk, is discussed for the case study, as well as the consequences of the specificconstruction contract. The acceptable aggregate risk, i.e. the risk the local and national authoritiescan permit, is elaborated.
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- Bismut, Elizabeth, et al.
(författare)
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Optimal adaptive decision rules in geotechnical construction considering uncertainty
- 2023
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Ingår i: Geotechnique. - : Emerald. - 0016-8505 .- 1751-7656.
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Tidskriftsartikel (refereegranskat)abstract
- To optimally design a geotechnical engineering structure, an iterative decision-making process is required due to the prevailing uncertainty of the ground conditions. At present, these decisions are taken based on simple deterministic rules and models. This paper proposes a risk-based decision-theoretic framework to the optimal planning for geotechnical construction. This framework combines geotechnical probabilistic models, cost analysis using Monte Carlo simulation and the observational method. The framework is illustrated on the design of the surcharge for an embankment on soft soil, whereby the optimal preloading sequence of added surcharge is adapted to the observed settlement. The approach balances the cost of surcharge material against financial penalties related to project delays and insufficient overconsolidation, which causes damage due to residual settlement. The result is a preloading strategy that optimally accounts for information obtained from settlement measurements under uncertain ground conditions. The findings highlight the potential of using risk-based decision planning in geotechnical engineering, in particular in combination with the observational method. For the investigated case-study, we observe a reduction in the expected cost in the order of 25%.
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- Bjureland, William, 1987-, et al.
(författare)
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Dimensionering av sprutbetongförstärkning för lösa block med sannolikhetsbaserade metoder
- 2020
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Användning av sannolikhetsbaserade metoder för dimensionering av bergförstärkning är ett tillvägagångssätt som är accepterat i Eurokoderna. Vid dimensionering med dessa metoder beaktas osäkerheter stringent genom att ansätta sannolikhetsfördelningar för relevanta parametrar. Konstruktionens säkerhet säkerställs genom att verifiera att sannolikheten att överskrida bärförmågan är lägre än den i Eurokoderna kravställda brottsannolikheten. För tillämpning av sannolikhetsbaserade metoder för dimensionering av sprutbetongförstärkning för lösa block har ett problem varit att data saknats för att kunna beskriva relevanta parametrar med representativa sannolikhetsfördelningar. Dessutom samverkar de olika brottmoderna och måste därför betraktas ur ett systemperspektiv, vilket inte beaktats i tidigare studier. I denna artikel presenteras resultatet av ett doktorandprojekt med finansiering av SBUF, BeFo, SVC och SKB. Baserat på ovanstående aspekter presenteras en metodik för dimensionering av sprutbetongförstärkning för lösa block med sannolikhetsbaserade metoder. Inledningsvis presenteras sannolikhetsfördelningar för sprutbetongens parametrar baserat på en stor mängd analyserade data från Citybanan. Därefter presenteras den utvecklade dimensioneringsmetodiken, vilken bygger på att en initial dimensionering av sprutbetongen utförs innan tunneldrivningen påbörjas och att den applicerade sprutbetongens bärförmåga därefter verifieras med hjälp av kontrollmätningar från fält och Bayesiansk statistik.
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| 8. |
- Bjureland, William, 1987-, et al.
(författare)
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Influence of spatially varying thickness on load-bearing capacity of shotcrete
- 2020
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier. - 0886-7798 .- 1878-4364. ; 98
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Tidskriftsartikel (refereegranskat)abstract
- A common approach to verify a shotcrete layer's ability to secure blocks that can exist between rockbolts in a tunnel is to use analytical calculations. For this situation, an attractive approach to account for variability in the shotcrete parameters is to use reliability-based methods. Variability can then be accounted for by assigning suitable probability distributions to all relevant input parameters. Structural safety can be ensured by verifying that the probability of limit exceedance is smaller than an acceptable target probability of failure. However, even though analytical calculations and reliability-based methods can be used to design shotcrete support, one of the commonly made basic assumptions is that the load-bearing capacity of the shotcrete is governed by the spatial average of the input parameters. Thus, the spatial variability of the parameters are neglected. As a result, if the capacity is governed by the lowest value of a certain parameter, this assumption is non-conservative. In this paper, we present a novel approach in which the minimum of either the spatial average of a shotcrete slab of varying thickness, or the spatial average along the periphery of a loose block of that same slab, is used to estimate the load-bearing capacity of the shotcrete in a tunnel. The approach is based on results from numerical simulations of a shotcrete slab that we perform to investigate the effect that a spatially varying thickness has on the flexural load-bearing capacity of the slab. The results from the simulations show that the shotcrete's flexural load-bearing capacity might be overestimated when using the spatial average of shotcrete thickness between four rockbolts in design. Using the presented approach, the spatial variability of shotcrete thickness can be accounted for in practical design of tunnels without complex and time-consuming numerical simulations.
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| 9. |
- Bjureland, William, et al.
(författare)
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Probability distributions of shotcrete parameters for reliability-based analyses of rock tunnel support
- 2019
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier. - 0886-7798 .- 1878-4364. ; 87, s. 15-26
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Tidskriftsartikel (refereegranskat)abstract
- A common support measure for underground excavations in jointed rock masses to support loose blocks is to apply a thin shotcrete layer to the periphery of the excavation and systematically install rockbolts into the surrounding rock mass. In this support system, large blocks are carried by the rockbolts and small blocks are carried by the thin shotcrete layer. To verify the shotcrete layer's load-bearing capacity and to stringently account for the large uncertainties incorporated in the variables involved in determining its capacity, analytical calculations in combination with reliability-based methods can be used. However, a lack of knowledge exists regarding the magnitude and uncertainty of shotcrete characteristics (thickness, adhesion, flexural tensile strength, residual flexural tensile strength, and compressive strength), making it difficult to apply reliability-based methods. A statistical quantification of these characteristics is therefore important to facilitate reliability-based methods in design and verification of shotcrete support. In this paper, we illustrate how shotcrete support against small loose blocks can be viewed as a correlated conditional structural system and how this system can be analyzed using reliability-based methods. In addition, we present a unique amount of data for the aforementioned variables, which are all incorporated in the design and verification of a shotcrete layer's ability to sustain loads from small loose blocks. Based on the presented data, we statistically quantify and propose suitable probability distributions for each variable. Lastly, we illustrate how the proposed probability distributions can be used in the design process to calculate the probability of exceeding the shotcrete's load-bearing capacity. Both the probabilistic quantification and the defined correlated conditional structural system along with the illustrative calculation example are followed by a discussion of their implications.
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