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European feedback on post-mining seismicity

Contrucci Isabelle, Namjesnik Dalija, Niemz Peter, Primo Paloma, Kotyrba Andrzej, Mutke Grzegorz, Konicek Petr, Dominique Pascal, Rudolph Tobias, Möllerherm Stefan, Kinscher Jannes, Klein Emmanuelle, Cesca Simone

Journal of Sustainable Mining

2023

Vol. 22. iss. 3

195--218

Following the Paris Agreement adopted in 2015, Europe has committed to reducing its greenhouse gas emissions. In this context, the abandonment of coal as an energy source, both in terms of consumption and production, will lead to the closure of many mines in the years to come. Mine closure guidelines to manage residual mining risks already exist in European countries. However, they do not include post-mining seismic risk management due to a lack of sufﬁcient studies and knowledge on this subject. After mining closure, the ﬂooding of the mining works leads to hydromechanical loading of the underground and, in the longer term, to diffusion and an increase in the pore pressure. These conditions can lead, in certain situations, to the reactivation of tectonic faults, which may cause seismic events strong enough to be felt on the surface or even produce damage. Events of lower magnitudes, usually attributed to the remobilization of old mining works, are referred to as post-mining seismic hazards. The European RFCS PostMinQuake project, which started in 2020, aims to study this hazard at ﬁve mining basins located in France, Germany, Poland and the Czech Republic, known to have experienced signiﬁcant seismicity during their operation. This analysis, based on the feedback of the partners of the project, aims to frame an inventory of the ﬁve studied mining basins, which all encounter post-mining seismicity problem today. Three basins out of ﬁve show events with local magnitudes of the order of 3-3.5, which took place between nine and thirteen years after the closure of the mines. Even though the magnitudes of these earthquakes are small to moderate, they are felt on the surface as they occur at shallow depths. In all of the considered countries, a national seismological network exists, however, none of them is fully dedicated to post-mining seismic monitoring. These networks generally consist of a sparse mesh of stations, which does not allow the detection of events of magnitude less than 1 and the location of events have high spatial uncertainties. France is not an exception, but it relies on microseismic monitoring to detect early signs of instability at the level of mining structures and to anticipate the possible appearance of surface disorders. Out of the ﬁve basins that are studied, the Gardanne basin, which has been monitored since 2008, is the most documented case study of post-mining seismicity. This article also shows the difﬁculty in identifying the key conditions and factors that can lead to the remobilization of faults.

Hygric properties of gelatine-based adhesives

Bachtiara Erik Valentine, Sehaqui Houssine, Niemz Peter

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

2014

No. 85

7--11

Hygric Properties of Gelatine-Based Adhesives. Studies about wood adhesives have been carried out for several years in the Institute for Building Materials ETH Zürich. Several investigations about adhesives that have been published are [2, 3, 4, 5, 6]. In this work, three types of gelatine-based adhesives (animal glues) which are hide, bone and fish glue were investigated. As a comparator, one type of synthetic adhesive one-component moisture-curing polyurethane adhesive (1C-PUR) was investigated simultaneously. The focuses of this work are on moisture transport and sorption properties of the adhesives. Therefore, two experimental tests diffusion test and sorption test were performed. In the results from diffusion test, it is found that animal glues have a very less vapor resistance against moisture. Which means that water can easily diffuse through the animal glues. The results of sorption test shows a higher moisture content inside animal glues compare to synthetic glue. It recorded for a very wet condition (20°C/95% RH) the moisture content reach up to approximately 60% for animal glues and only 3% for synthetic glue.

Modelling the mechanical stresses in adhesive joints of wood bondings

Hering Stefan, Niemz Peter

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

2012

No. 78

60--75

Modelling the mechanical stresses in adhesive joints of wood bondings. Wood bondings have been used in timber construction and many other applications for a long time. Using layered arrangements, the homogenisation of the anisotropic physical and mechanical properties of solid wood reduce the influence of moisture and improve the mechanical behaviour of structural elements. However, new weak points can be created and effects such as debonding and delamination can occur. These failure characteristics depend on mechanical and hygroscopic loading as well as the composition of the structural components. Hence, delamination can be reduced by adjusting the properties of the appropriate adherend or by changing the structural assembly of the specific elements. Using finite element analysis, the influence of the adherend properties during the testing procedure and an example of cross-laminated wood panels on the adhesive load are investigated. The results show significant differences in the glue line stress distribution for varied growth ring angle, longitudinal Young’s modulus, diffusion as well as swelling and shrinkage properties.