Green roofs play a significant role in sustainable drainage systems. They form absorbent surfaces for rainwater, which they retain with the aid of profile and plants. Such roofs therefore take an active part in improving the climatic conditions of a city and, more broadly, the water balance of urbanized areas. One of the factors influencing the hydrological efficiency of green roofs is the drainage layer. In the article, column studies were carried out under field conditions involving the comparison of the retention abilities of two aggregates serving as the drainage layer of green roofs, i.e. Leca® and quartzite grit. The average retention of the substrate was 48%; for a 5 cm drainage layer of Leca® retention was 57%, for a 10 cm layer of Leca average retention was 61%. For a 5 cm layer of quartzite grit average retention was 50%, for 10 cm layer of quartzite grit 53%. The highest retention was obtained for the column with the substrate and 10-centimeter layer of Leca®. At the same time, it was shown that Leca® is a better retention material than quartzite grit. The initial state of substrate moisture content from a green roof appears to be a significant factor in reducing rainfall runoff from a green roof; the ob-tained values of initial moisture content made for a higher correlation than the antecedent dry weather period.

This article focuses on the difficulties in ensuring longwall stability resulting from the wrong geometric form of the structure of powered support sections. The authors proved, based on the in-situ measurements and numerical calculations, that proper cooperation of the support with the rock mass requires correct determination of the support point for the hydraulic legs along the length of the canopy (ratio), as well as the inclination of the shield support of the section of the powered roof support. The lack of these two fundamental elements may lead to roof drops that directly impact the production results and safety of the people working underground. Another matter arising from the incorrect geometric form of the construction are the values of forces created in the node connecting the canopy with the caving shield, which can make a major contribution to limit the practical range of the operational height of the powered roof support (due to interaction of powered support with rockmass) in terms of the operating range offered by the manufacturer of the powered support. The operating of the powered roof support in some height ranges may hinder, or even in certain cases prevent, the operator of powered support, moving the shields and placing them with the proper geometry (ensuring parallelism between the canopy and the floor bases of the section).

Effective use of energy in various branches of economy is one of world trends in development of power engineering. Relevant energy consumption occurs during exploitation of buildings, so there is still potential to diminish it as far as heating, ventilation, and air conditioning are concerned. Particularly in summer season, the choice of respective roofing colour can play a decisive role for the heat flux transferred to the inside of the object. Decrease of heat flux causes a lower heat burden to the building and lower power consumption by the air conditioning systems. In winter, on the contrary, heat flux transferred to building’s interior should be higher, as a result, demand of energy for heating will be lower. However, calculations of the heat flux require that energy balance must be made for the object. Unfortunately, not all producers of roofing covers inform about the values of reflectivity and thermal emissivity of their products, which is, in turn, necessary for calculations. In the present paper, research methodology elaborated by authors is proposed for determination of thermal emissivity of roofing covers. The paper presents test stand, methodology, and research results for roofing paper in blue colour (as an example) for which the thermal emissivity is an unknown parameter.

This article deals with the problem of determining the resistance of end-plate connections. A nonlinear FEM model of the joint was constructed in order to predict its carrying capacity. A standard code procedure was done as well. The analyses have been done to assess atypical end-plate joints designed and constructed as a part of roof structures.

The article shows the need to take into account the principles of sustainable development in the field of the revitalization of space, and point out green roofs as a tool in this process. It is presented in the light of the green city concept, and the criteria of the European Green City Index. The article shows the ecological, social and economic benefits of green roofs (starting from the retrieval of green areas in the urbanized space, the reduction of heat island effects, up to the integration function of green roofs), which is illustrated by a few case studies of applying green roofs within revitalization projects. The article indicates also legal incentives, as well as programs directed to the development of green roofs around the world, pointing out a range of factors to consider also for Polish cities.

In this paper, transient analysis on heat transfer across the residential building roof having various materials like wood wool, phase change material and weathering tile is performed by numerical simulation technique. 2-dimensional roof model is created, checked for grid independency and validated with the experimental results. Three different roof structures are included in this study namely roof with (i). Concrete and weathering tile, (ii). Concrete, phase change material and weathering tile and (iii). Concrete, phase change material, wood wool and weathering tile. Roof type 3 restricts 13% of heat entering the room in comparison with roof having only concrete and weathering tile. Also the effect of various roof layers’ thickness in the roof type 3 is investigated and identifi ed that the wood wool plays the major role in arresting the entry of heat in to the room. The average reduction of heat is about 10% for an increase of a unit thickness of wood wool layer.

Geodesic measurements of mining area deformations indicate that their description fails to be regular,

as opposed to what the predictions based on the relationships of the geometric-integral theory suggest.

The Knothe theory, most commonly applied in that case, considers such parameters as the exploitation

coefficient a and the angle of the main influences range tgβ, describing the geomechanical properties of the

medium, as well as the mining conditions. The study shows that the values of the parameters a = 0.8 and

tgβ = 2.0, most commonly adopted for the prediction of surface deformation, are not entirely adequate in

describing each and every mining situation in the analysed rock mass. Therefore, the paper aims to propose

methodology for determining the value of exploitation coefficient a, which allows to predict the values

of surface subsidence caused by underground coal mining with roof caving, depending on geological and

mining conditions. The characteristics of the analysed areas show that the following factors affect surface

subsidence: thickness of overburden, type of overburden strata, type of Carboniferous strata, rock mass

disturbance and depth of exploitation. These factors may allow to determine the exploitation coefficient a,

used in the Knothe theory for surface deformation prediction.

The efficient protection (support reinforcement) of a wall and heading crossing ensures continuity of the production cycle, and that is a quick moving of the scraper conveyor to the wall. Using low or high bolting as a support reinforcement element in wall and heading crossings allows for the elimination of traditional methods of maintaining longwall-gate crossings, and therefore allows for the efficient use high performance modern wall complexes. The paper presents the long underground experience, of the Knurów–Szczygłowice mine of efficient support wall and heading crossing maintenance, which was bolted to the rock mass with the usage of two pairs of bolts, showing full technical and economical usefulness of this support reinforcement method. The article also highlights work safety and the increasingly common usage of endoscopies when specifying the range of crack areas which directly effects the proper choice in number, load-capacity and length of the used bolts. The underground studies the measurements of the reach of the zones of fracturing and roof stratification (using endoscopes and wire type stratification meters) and the laboratory tests (using the test stand) have allowed to determine the safety factor for maintenance of the longwall gangway crossing, directly resulting in the necessity to install additional reinforcement. The value of the safety factor Sbsc-ch greater than 1 is advantageous and safe, and the value less than or equal to 1 can lead to a significant deterioration of the conditions of maintenance of a wall and heading crossing which was bolted.

The presented article describes the relationship between lithological and facies development of reservoir rocks in the area of the roof elevation of the Weissliegend sandstones, with a particular emphasis on the influence of elevation on the occurrence of low mineralization zones in the deposit area. To illustrate the variability of the deposit parameters, closely related to the facies and lithological conditions of the host rocks, three-dimensional lithological and geochemical models for two research areas were developed using the geostatistical methods and based on field observations and the sampling of the deposit. The research area includes parts of the Northern Elevation of Rudna and the surrounding depressions within the boundaries of the Sieroszowice and Rudna deposits. Based on cross-sections of the 3D models, a different deposit formation in the roof elevation area of sandstone formations has been characterized; the lithological profile is defined as „atypical” due to the absence of a copper-bearing shale series, the most characteristic layer for copper ore deposits in the Fore -Sudetic monocline. Large variations in the shape of the deposit and the irregular boundaries of both balance mineralization and enclaves of gangue have been confirmed. The presence of large-scale enclaves of igneous rock in the entire profile of the Lower Zechstein rocks (areas without the balance copper mineralization) and small areas of gangue (sandstone) enriched with anhydrite binders adjacent to the parts of balance deposit located in argillaceous sandstone has been revealed. The possibility of the occurrence of gangue, in the area of the roof elevation of the Weissliegend sandstones directly adjacent to the border with calcareous dolomite, and irregular gangue partings in sandstone formations in the balance deposit was indicated. In addition, small areas of strong enrichment in Cu sulphides were observed in the contact zones between sulphate and clay binders in the Weissliegend sandstone series.

The use of computer techniques at the design stage of industrial facilities is essential in modern times. The ability to shorten the time required to develop a project and assess the safety of the use of assumptions, often enables the reduction of the costs incurred in the future. The possibility to skip expensive prototype tests by using 3D prototyping is why it is currently the prevailing model in the design of industrial facilities, including in the mining industry. In the case of a longwall working, its stability requires the maintenance of the geometric continuity of floor rocks in cooperation with a powered roof support.

The paper investigates the problem of longwall working stability under the influence of roof properties, coal properties, shield loading and the roof-floor interaction. The longwall working stability is represented by an index, factor of safety (FOS), and is correlated with a previously proposed roof capacity index ‘g‘. The topic of the paper does address an issue of potential interest.

The assessment of the stability of the roof in longwalls was based on the numerical analysis of the factor of safety (FOS), using the Mohr-Coulomb stress criterion. The Mohr-Coulomb stress criterion enables the prediction of the occurrence of failures when the connection of the maximum tensile principal stress σ1 and the minimum compressive principal stress σ3 exceed relevant stress limits. The criterion is used for materials which indicates distinct tensile and compressive characteristics. The numerical method presented in the paper can be utilized in evaluating the mining natural hazards through predicting the parameters, which determine the roof maintenance in the longwall working.

One of the purposes of the numerical analysis was to draw attention to the possibilities that are currently created by specialized software as an important element accompanying the modern design process, which forms part of intelligent underground mining 4.0.

An uniaxial compression mechanical model for the roof rock-coal (RRC) composite sample was established in order to study the effects of height ratio of roof rock to coal on the structural strength of composite sample. The composite sample strengths under different height ratios were established through stress and strain analysis of the sample extracted from the interface. The coal strength near the interface is enhanced and rock strength near the interface weakened. The structural strength of composite sample is synthetically determined by the strengths of rock and coal near and far away from the interface. The area with a low strength in composite sample is destroyed firstly. An analytical model was proposed and discussed by conducting uniaxial compression tests for sandstone-coal composite samples with different height ratios, and it was found that the structural strength and elastic modulus decrease with a decrease in height ratio. The coal strengths far away from the interface determine the structural strengths of composite sample under different height ratios, which are the main control factor for the structural strength in this test. Due to its lowest strength, the rock near the interface first experienced a tensile spalling failure at the height ratio of 9:1, without causing the structural failure of composite sample. The coal failure induces the final failure of composite sample.

The most important challenges in the construction field is to do the experimentation of the designing at real time. It leads to the wastage of the materials and time consuming process. In this paper, an artificial neural network based model for the verification of sigma section characteristics like shear centre and deflection are designed and verified. The physical properties like weight, depth, flange, lip, outer web, thickness, and area to bring shear centre are used in the model. Similarly, weight, purlin centres with allowable loading of different values used in the model for deflection verification. The overall average error rate as 1.278 percent to the shear centre and 2.967 percent to the deflection are achieved by the model successfully. The proposed model will act as supportive tool to the steel roof constructors, engineers, and designers who are involved in construction as well as in the section fabricators industry.

Types of wind storms in Poland and examples of economic damage, threats to human life and health caused by two extreme wind events are presented. Then, a house with the roof blown-off during the derecho wind storm in Poland on August 11-12, 2017, is considered. Based on the rafter framing of the house, i.e. wooden roof structure elements and roof covered, the weight of the roof is calculated. Two cases of the strong connection between rafter plates and knee walls are estimated. With the estimation of connection strength between rafter plates and knee walls, it was possible to calculate the total force required to blow-off the roof of the house. Next, an aerodynamic force acting on the house is calculated using pressure coefficients for a low-rise house with a gable roof. The pressure coefficients were taken from the Tokyo Polytechnic University aerodynamic database. The aerodynamic force acting on the roof blown-off was calculated for a low-rise building with a gable roof for similar ratios for length, width, and height. Three wind directions, for the unknown orientation of the building, were considered, i.e. the wind direction perpendicular, parallel, and oblique to the gable wall. By comparison, the aerodynamic force with the total force required to blow-off the roof of the house, it was possible to calculate the critical wind speed needed for the roof blown-off. This wind speed is much bigger than measured by meteorological stations on the path of the derecho.