This study analyses building foundation models with and without expansion joints, investigating the effects of deep soil mixing (DSM) on settlement and the effect of expansion joints on stress distribution. Numerical models were developed to evaluate the impact of DSM parameters, including diameter, length, and spacing, as well as the influence of mini-piles and anchorage systems on the support structure, and showed that increasing the diameter and length of DSM columns significantly reduced settlements, achieving reductions of 81-94% in models with expansion joints and 77-94% in models without expansion joints. In models with expansion joints and without joints, closely spaced DSM applications (1.3 m) have significantly reduced settlement and also prevented non-uniform settlement. Expansion joints limit stress interaction between blocks, interrupt stress continuity, and thus prevent the propagation of secondary stresses arising from non-uniform settlement, temperature effects, and stiffness differences. The relationship between DSM length and settlement is similar to the relationship between DSM diameter and settlement. For this study, a DSM length of 12 meters and a DSM diameter of 0.4 meters were determined as the ideal DSM parameters. DSM configuration with 12 meter length, 0.4 m diameter, and 1.3 m spacing was identified as the most efficient solution in terms of both performance and cost for this project. These findings indicate that expansion joints are a secondary parameter in settlement control under DSM-improved soil conditions, that soil improvement properties should be prioritised in design evaluations, and that expansion joints are an important criterion in terms of stress distribution.

The Książ Geodynamic Laboratory is a unique research centre, both nationally and globally, conducting a comprehensive research program in the field of Earth sciences. It primarily focuses on studying tidal and non-tidal phenomena using water-tube tiltmeters. Over the past decade, the Laboratory has developed a research program aimed at predicting seismic events (strong seismic shocks with a magnitude of ≥3.6 of natural origin) by analyzing changes in stress conditions within the orogen. The modification of the water-tube tiltmeter recording system proposed in this article will significantly enhance the quality of ongoing research. First and foremost, modernisation of the water-tube tiltmeter detector will increase the instrument’s sensitivity by two orders of magnitude, enabling the measurement of water level changes at the picometer scale. Equally important, the upgrade will allow real-time data acquisition. This feature is critical for the practical application of observations, as real-time results can be used to forecast the risk of strong seismic shocks in two key Polish mining regions: the Upper Silesian Coal Basin and the Legnica- Głogów Copper District. Previous studies based on archival data (2013-2017) have confirmed the high effectiveness of this forecasting procedure (>95%). The insights gained will undoubtedly contribute significantly to mitigating seismic hazards in underground mines.

Urbanisation, economic development and the growth of the world’s population contribute to a continuous increase in demand for mineral aggregates. In many countries and regions (Arab countries, some Asian countries) there is a significant deficit of aggregates, contributing to unsustainable exploitation with a negative environmental impact. To regulate this unfavourable situation related to the management of aggregate resources, one of the main conclusions of the UNEP 2019 Report is the need for a universal introduction of planning and monitoring of the process of obtaining natural aggregates. The paper presents changes in the extraction and production of aggregates between 2005-2022 for Poland and the European Union (2008-2022). These changes confirm the dependence of aggregate production on cement consumption in both Poland and the EU. Econometric models estimated for these relationships were then used to forecast aggregate production. The relatively small errors shown in the ex-post forecasts (2020-2023) confirm the possibility of using the estimated dependencies for ex-ante forecasts (2024-2027), which is illustrated, for example, by the production of mineral aggregates in Poland and the EU.

Conducting mining operations in fault zones is a very challenging task, both from a technological perspective and also due to the safety of the miners. Therefore, it is essential to determine the impact of mining parameters on the possibility of fault activation, which in many cases leads to high seismic activity. The article presents the results of numerical analyses of the impact of longwall mining in the vicinity of tectonic faults on the state of stress in the rock masses. The authors demonstrated the influence of the advancement of the longwall face and its direction on the risk of rock burst, both for mining conducted in the footwall and hanging wall.

The changes in the physical and mechanical properties of rocks under high temperatures can impact the construction safety and stability of underground geotechnical engineering. This study focuses on red sandstone treated at different temperatures, employing nuclear magnetic resonance (NMR) spectroscopy to reveal alterations in the internal pore distribution due to elevated temperatures. The results indicate that high temperatures lead to the formation of micro- to meso scale pores and macro-scale pores and cracks. Additionally, high temperatures cause a significant reduction in load-bearing capacity, accompanied by changes in creep behaviour, including a shortened steady-state creep time and an increased strain threshold for rock failure. To more accurately describe the creep behaviour of red sandstone under different temperatures and stress conditions, a novel non-constant creep model is proposed, combining a generalised Kelvin body and a fractional viscoplastic body to demonstrate its versatility in elastic, viscoelastic, and viscoplastic deformation. The model parameters are determined through numerical optimisation, and the model’s reliability is confirmed by comparing theoretical curves with experimental data. Sensitivity analysis highlights the critical roles of parameters such as shear modulus, viscosity coefficient, fractional order, and characteristic parameters in capturing various creep patterns, emphasising the model’s wide applicability. This research provides profound insights into the physical and mechanical responses of red sandstone to high temperatures and offers valuable information for engineering and geological applications in relevant fields.

One of the techniques commonly applied today for deep foundation construction is based on self-drilling injection micropiles. Micropiles are structural elements intended primarily for reinforcing foundations and buildings, particularly under difficult terrain conditions. The goal of the tests presented herein is to inspect the fatigue resistance, strength and ductility of injection micropiles formed from 28Mn6 steel at loads significantly exceeding the values defined for the fatigue test in the requirements of the relevant European Assessment Document (EAD). The test results and the micropile bar strain model εM presented in this paper are primarily of interest to designers for the purposes of determining the fatigue resistance of steel micropiles, which find particular application in land degraded by mining activity that is characterised by frequent terrain vibration and mining-induced tremors. None of the R25N injection micropile bars failed during the fatigue resistance testing at 2·106 cycles at a load Fu = 0.7·FRe0.2 (under the yield strength of the 28Mn6 steel) as well as at Fu = 1.0·FRe0.2 and Fu = 1.2·FRe0.2, where the bars operated at the limit of and significantly above the load FRe0.2 which results in stress at the yield point of the 28Mn6 steel. Furthermore, the bar tests conducted at static and cyclic loading demonstrated the high strength and good ductility of the 28Mn6 steel.

The stress field of the roadway under multi-seam mining is complex due to multiple mining disturbances. The bolting control of the roadway under multi-seam mining has attracted wide concern. Moreover, conventional metal supporting materials in the coal rib are prone to sparks when shearer works, and new bolting materials are urgently needed. Taking a track roadway under multi-seam mining in China as the engineering case, the mining-induced stress field of the track roadway under multi-seam mining was investigated through numerical simulation and lab and field tests. The test evaluated the mechanical behaviour of FRP bolts and rebar bolts, as well as their anchorage performance under different conditions. Comparative analysis was conducted on the deformation and failure characteristics of the roadway under different bolting parameters to determine an optimised bolting scheme for the track roadway in the I011501 working face. The results show that the goafs and the remaining coal pillars in the overlying coal seams increase the stress in the track roadway in the I011501 working face, especially for the lower rib and roof. The tensile force of the 27 mm-diameter FRP bolt is 1.2 times that of the 22 mm-diameter rebar bolt. The shear strength of the full-length anchored FRP bolt is 70.8% higher than that of the end-anchored bolt. The peak stress of the full-length-anchored bolt is in the shallow coal and rock mass. The optimised bolting scheme of the track roadway subject to multi-seam mining is determined, and the cost of the optimised bolting scheme is lower by about 25.2%, as compared with the primary bolting scheme. Numerical simulation and field application results indicate that the optimised bolting scheme can significantly reduce the deformation and plastic failure of the track roadway in the I011501 working face, which is under multi-seam mining conditions.

The paper discusses a variety of serious challenges facing the Polish energy sector until 2040. These challenging tasks largely result from intensive works in the European Union on the finalisation of measures implementing a zero-carbon economy, as well as social (Covid-19), political and military events, both global and regional (war in Ukraine). After analysing the present condition of the energy sector, the authors proposed a modification of Poland’s energy policy, pointing out that the transformation of the national electricity system towards zero-carbon energy requires, on the one hand, speeding up investments in renewable sources, but on the other hand, insuring this process by own controllable generation sources. The paper also defines the conditions that should be met to achieve the highest possible share of non-carbon energy in the national energy mix by 2040.

Currently available field rock mass deformability determination methods are rather difficult to perform, due to their complexity and a time-consuming nature.This article shows results of a suitability assessment of a Pen206 borehole jack (a hydraulic penetrometer) for field rock mass deformability measurements.This type of the borehole jack is widely used in Polish hard coal mining industry.It was originally intended only for quick rock mass strength parameters determination.This article describes an analysis and scope of basic modifications performed mainly on a borehole jack head.It includes discussion of results with possible directions for future development of the device.

A mathematical model for the purposes of methane hazard assessment in mines was developed in the Central Mining Institute as part of the statutory activities conducted in 2017 and 2018. The model describes the course of kinetics of methane sorption on coal samples while taking into account the diffusion coefficient. The paper presents the formulas describing the mathematical model of methane emission from coal sidewall to longwall working, taking into account the sorption properties of coal -sorption capacity of coal (related to methane) and the effective diffusion coefficient of methane in coal. In the light of the conducted research, such a methodology for describing this phenomenon enables a more precise determination of the amount of methane released to the longwall from the exploited coal seam, which in turn makes it possible to select appropriate methane prevention measures.