Johan Spross

• Doctor of Philosophy
• Researcher at KTH Royal Institute of Technology

Safety in geotechnical design has evolved from experience and judgment using overall factor of safety approaches to design methods in modern codes of practice which apply partial factors to loads and to strength parameters or resistances. Explicit treatment of uncertainties using probabilistic methods has been receiving more attention recently, bot...

The current Eurocode revision process is sought to improve Eurocode 7 for application to rock engineering, while including only techniques and procedures that are in widespread customary use. The revision process has exposed much about the application of the Eurocodes to rock engineering, thereby offering hints as to what material should be include...

The second generation of Eurocode 7 aims at covering ground, including both soil and rock. Current practice of ground engineering forms the basis, and the aim is to include rock engineering, improving ease of use, harmonization of regulations, and covering new developments. This paper deals with EN 1997 part 1 addressing the general rules of geotec...

Time and cost estimation of tunneling projects is usually performed in a deterministic manner. However, because the deterministic approach is not capable of dealing with uncertainty, probabilistic methods have been developed over the years to better account for this problem. Three models of this type are the Decision Aids for Tunneling (DAT) and tw...

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 geotech...

Construction and infrastructure projects account for a large share of global greenhouse gas emissions. Included in these projects are geotechnical engineering works, which cause environmental impact and costs throughout their life cycle. In the geotechnical design process, the geotechnical engineer often has design choices where different methods a...

Probabilistic time and cost estimation is a useful approach to assist decision-making under uncertainty concerning budget and duration of tunneling projects. In recent years, several models have been developed that can be used for this purpose, where the subjective assessments of the values of input parameters conducted by estimators are of crucial...

The transition to a fossil-free energy matrix may require large quantities of hydrogen gas, which could be stored efficiently in underground lined rock caverns (LRCs). Since the consequences of failure can be catastrophic, the LRC design needs to have a small failure probability. However, the current deterministic design practice for LRCs limits th...

Emissions from infrastructure projects and construction projects have a large impact on the environment. Construction activities and materials, including geotechnical engineering works, account for a great share of that impact and the monetary costs of the projects. In railway projects, crushed bedrock is often used as fill material in the embankme...

(Link to free full text: https://rpsonline.com.sg/proceedings/isgsr2022/html/00-001.html ) This bright spark lecture opens by noting that geological and geotechnical uncertainty affects not only a tunnel’s structural safety but also its cost and time plan. Cost overruns and delays of underground excavation projects in rock are, in fact, a huge prob...

The storage of hydrogen gas in lined rock caverns (LRCs) may enable the implementation of the first large-scale fossil-free steelmaking process in Sweden, but filling such storage causes joints in the rock mass to open, concentrating strains in the lining. The structural interaction between the LRC components must be able to reduce the strain conce...

We describe an adaptive Markov chain Monte Carlo method suitable for the estimation of rare failure probabilities in complex probabilistic models. This method, the Accelerated Weight Histogram (AWH) method, has its origin in statistical physics (Lidmar, 2012) and has successfully been applied to molecular dynamics simulations in biophysics. Here we...

Heavy vibratory plate compaction is an efficient technique for improvement of granular soils. However, its practical application is limited by insufficient knowledge about the compaction process and the optimum procedure of execution. In this study, compaction tests were conducted in the field with a 40.5-ton heavy vibratory plate compactor. The si...

(Full text here: https://rpsonline.com.sg/rps2prod/isrerm2022/epro/html/MS-13-031.xml ) Design decisions in geotechnical engineering typically need to be made under considerable uncertainty, both regarding present geotechnical conditions and future events occurring during the service life of the structure. To optimize the utility of societal inve...

Probabilistic time estimation is an essential part of proper risk management in tunneling projects. In recent decades, several models have been developed for this purpose, one of which was developed by Isaksson and Stille (Rock Mech Rock Eng 38:373–398, 2005). In this paper, Isaksson and Stille’s probabilistic time and cost estimation model was imp...

The storage of hydrogen gas in underground lined rock caverns (LRCs) enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel. Predicting the response of rock mass is important to ensure that gas leakage due to rupture of the steel lining does not occur. Analytical and numerical models can be...

Modern tunnelling in rock relies heavily on information from monitoring and observations during construction as a means to reduce the considerable uncertainty that originates from a lack of knowledge about the ground conditions. By formally integrating the monitoring information into the structural safety evaluation, a comprehensive risk-based desi...

Rock tunnel construction is associated with considerable geotechnical uncertainty, often due to limited knowledge about the ground conditions. This warrants the use of stringent risk management procedures to reduce the likelihood of cost increases, delays, and structural failure events. The observational method is often promoted as a tool to achiev...

Geotechnical engineering work contributes to the total environmental impact and monetary cost occurring from the construction sector. Decisions made regarding geotechnical engineering aspects have a profound effect on the environmental impact and the monetary cost of the structure during its life cycle. Life Cycle Assessment (LCA) and Life Cycle Co...

Deep mixing columns commonly are used to reduce settlement under road and railway embankments on soft soils. However, the structural behavior of the soil volume improved with columns is difficult to predict, due to the existence of considerable uncertainties in the mixing process and the structural interaction between the columns and the untreated...

Unexpected and unforeseen geotechnical events cause large cost increases in geotechnical engineering projects and threaten construction workers’ health and safety all around the world. Practical tools and guidelines for how to implement structured and effective risk management methods in geotechnical engineering projects are however few and rarely...

This article, based on a keynote lecture given at the Finnish Rock Mechanics Day 2019, discusses how structured risk management can be implemented to rock engineering projects. The suggested procedure is based on ISO 31000 and a recently published methodology for practical implementation of the standard to geotechnical engineering projects. The mai...

Efforts to decrease CO2 emissions in the Swedish steelmaking process involve the use of industrial quantities of hydrogen gas supplied from large-scale Lined Rock Cavern (LRC) storages in order to eliminate the use of fossil fuels. This storage must be placed at sufficient depth so that the overburden is able to resist the uplifting gas pressure fr...

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 pr...

In comparison with other types of construction, the development of rock engineering design codes has been slow. Codes must, however, be developed with relevant discipline-specific characteristics in mind. This paper, therefore, presents a generic design framework for rock engineering. The framework is based on the presumption that rock engineering...

Preloading with a surcharge is today commonly used together with prefabricated vertical drains for embankment construction on clayey soil to accelerate primary consolidation and increase strength. Because of considerable uncertainty related mainly to the rate of consolidation, there is a need to account for this in the vertical drain and surcharge...

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 ca...

Lack of harmonisation between reliability-based design and the partial factor method in Eurocode 7 (EN 1997-1:2004) is preventing the widespread introduction of a risk-based concept in geotechnical design. This paper discusses how uncertainties are managed according to EN 1997-1:2004 and possible implications of not harmonising the current safety f...

Efforts to substitute the use of fossil fuels in industry by hydrogen gas requires the storage of large volumes of gas with a reliable pressure vessel design. The Hydrogen Breakthrough Ironmaking Technology (HYBRIT) initiative aims to make the whole steel making process in Sweden fossil-free with the storage of industrial scale quantities of hydrog...

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 shot...

Civil engineering structures are commonly monitored to assess their structural behaviour, using alarm thresholds to indicate when contingency actions are needed to improve safety. However, there is a need for guidelines on how to establish thresholds that ensure sufficient safety. This paper therefore proposes a general computational algorithm for...

Preloading is commonly used to accelerate primary consolidation and increase strength under embankments founded on highly compressible clay. By installing prefabricated vertical drains, this process can be even further accelerated. Because of significant geotechnical uncertainties, primarily regarding the vertical and horizontal coefficients of con...

The European design code for geotechnical engineering, EN-1997 Eurocode 7, is currently under revision. As design of underground openings in rock fundamentally differs from design of most other types of structures, the revised Eurocode 7 must be carefully formulated to be applicable to underground openings. This paper presents the authors’ view of...

In this paper, a reliability based framework for the assessment of sliding stability for concrete dams was presented. The framework consists of several parts based on the Probabilistic model code for concrete dams developed by Westberg-Wilde and Johansson and includes guidelines on how reliability based sliding stability assessment should be perfor...

The objective of HYBRIT RP1 is to explore and assess pathways to fossil-free energy-mining-iron-steel value chains and thereby provide a basis for industrial development activities and the necessary future transformative change in this field. A large-scale storage capacity for hydrogen gas is an important component of the proposed HYBRIT concept. U...

The Swedish Geotechnical Society has adopted a general methodology for risk management in geotechnical engineering projects to reduce the costs related to negative outcomes of geotechnical risks. This technical note highlights the main features of the methodology and strives to inspire the international geotechnical community to apply sensible risk...

Limitations with the current design using partial factors in Eurocode 7 have been identified. Uncertainties in the material properties are incorporated in both the cautious estimate of the characteristic value and the partial factor. Furthermore, the partial factor is fixed, which limits the opportunities to update the design when additional inform...

According to Eurocode 7, two accepted approaches for managing uncertainty in tunnel design are reliability-based methods and the observational method. Reliability-based methods account for uncertainty by acknowledging the random variation of the input parameters; the observational method does this by verifying the expected behavior from an initial...

Limitations with the current design using partial factors in Eurocode 7 have been identified. Uncertainties in the material properties are incorporated in both the cautious estimate of the characteristic value and the partial factor. Furthermore, the partial factor is fixed, which limits the opportunities to update the design when additional inform...

The Swedish national guidelines for design of the main structural support system in road and railway rock tunnels have been adjusted to cohere with Eurocode 7. In the design guidelines, the limit states that the designer should consider are specified. The main method to account for uncertainties in the Swedish guidelines is similar to the method pr...

The observational method in geotechnical engineering is an acceptable verification method for limit states in Eurocode 7, but the method is rarely used despite its potential savings. Some reasons may be its unclear safety definition and the lack of guidelines on how to establish whether the observational method is more favourable than conventional...

As concrete dams age, the need for remedial grouting to reduce the seepage and uplift pressure in the rock foundations under them increases. Based on a case study of a Swedish dam with very low calculated safety against sliding, this paper discusses the application of the observational method (as defined in Eurocode 7) to manage safety aspects duri...

Constructing sustainable structures in rock that satisfy all predefined technical specifications requires rational and effective construction methods. When the geotechnical behaviour is hard to predict, the European design code, Eurocode 7, suggests application of the observational method to verify that the performance is acceptable. The basic prin...

For concrete dams, cohesive strength often constitutes a significant share of the overall shear strength of partially bonded concrete-rock interfaces. However, cohesive strength is also associated with great uncertainties that may have a significant impact on the assessed stability of the analyzed structure. In this paper, the merits of including c...

To reduce the costs of unexpected geotechnical events in construction projects in Sweden, the Swedish Geotechnical Society has adopted a general methodology for risk management. In this paper, we exemplify how the proposed risk management philosophy could have been applied on a sheet-pile wall, which failed in 1992 in Stockholm because the design d...

For staging the construction of embankments on soft clay, an important aspect in deterministic or probabilistic stability analyses is the assessment of the representative average values and associated uncertainties for the undrained shear strength as the height of the embankment is sequentially increased. Assessments made prior to construction can...

According to Eurocode 7, the observational method is an accepted design method, where a preliminary design may be updated as the construction progresses. However, Eurocode 7 does not give any advice on how to relate the observations to the acceptable level of safety of the structure. In this paper, we outline a methodology for how to use deformatio...

Thesis available for download at http://www.diva-portal.org/smash/record.jsf?pid=diva2:712427&rvn=1 Building a sustainable structure in soil or rock that satisfies all predefined tech-nical requirements implies choosing a rational and effective construction method. An important aspect is how the performance of the structure is verified. For cases...

For tunnelling in rock in Sweden, the public authorities usually set stringent requirements on low groundwater inflow to the tunnel, to minimise the risk of building settlement and the environmental impact. In order to improve this groundwater control, the potential application of the observational method in this matter was studied. A comparison wa...

In probabilistic stability analyses of concrete dams founded on rock, the uplift pressure is often a parameter of major importance. In previous literature, it has been suggested that assessing uplift with pore pressure measurements, instead of using empirical assumptions, could improve the calculated dam safety. This paper presents a coherent metho...

Important features of the multivariate approach are discussed, and an extension to this approach is proposed whereby the total uncertainty in site investigation methods due to spatial averaging is assessed prior to its adoption. Results from a site investigation of spatially averaged values of undrained shear strength (S¯u) and the corresponding co...