Continuous Support for Roadways

Opening deeper coal seams requires constructing underground mine roadways in difficult geological conditions. Supporting of such roadways is subjected to a very high load from the rock mass. The types of roof supports used so far do not provide immediate support for the rock mass, which tends to converge the roadway, allowing for a rapid build-up of stresses in the surrounding rock mass. The article presents a new type of frame roadway support. This is a yielding support (consecutive arches are connected in a helical pattern), enabling the successive arches to be provided with initial load-bearing capacity already at the construction stage. The so-called unscrewing of the helix enables the arches to be pressed against the surface of the developed roadway with a controlled force. The introduction discusses the types of yielding roof supports used in the Polish mining industry and indicates their characteristic features. Further along in the article, the assumptions adopted for the construction of models to be tested and assumptions for the static and dynamic load to the models are defined, and the results of the model numerical tests are presented. The tests were aimed at comparing the qualitative behavior of the new roof support and the closed, circular support which is closest to it. The results of numerical tests confirmed the strength of the new solution not lower than the closed (circular) frame support, previously used in the most difficult geological conditions.

Application of 3D Scanning, Computer Simulations and Virtual Reality in the Redesigning Process of Selected Areas of Underground Transportation Routes in Coal Mining Industry

Nowadays designing of selected areas of mines underground workings can be effectively improved by the application of computer techniques: 3D scanning, computer simulations and Virtual Reality. This, in fact, would result in the more reliable design process, significantly reduced designing costs and efforts, and improvement of the mines staff’s safety. This scientific paper presents a method developed for redesigning of selected areas of mines underground workings in which auxiliary transport is carried out. The method combines 3D laser scanning technique with computer simulations carried out in a CAD/MBS system, in order to determine the location of potential collisions of the transported loads with the arch yielding support and the equipment. The obtained results, visualized using Virtual Reality, will form input data in the process of designing the selected area of the mines underground workings. Finally, an example of the application of the described method during transportation of big-size load is given.

Transactions between self-esteem and perceived conflict in romantic relationships: A 5-year longitudinal study

Self-esteem has been shown to be both predictive of and predicted by characteristics of romantic relationships. While there is an increasing number of studies yielding support for reciprocal influences between self-esteem and perceived conflict in romantic relationships, longitudinal transactions between these constructs from both partners’ perspectives have not been studied systematically to date. Our aim was to close this gap. To that end, we examined the transactional and longitudinal interplay between self-esteem and perceived relationship conflict in continuing romantic couples from a dyadic perspective. Our sample consisted of N = 1,093 young adult female–male relationships from the German Family Panel. Individuals’ self-esteem, perceived conflict frequency, and their perceptions of their partners’ dysfunctional conflict styles (i.e., unconstructive behavior, withdrawal) were examined annually throughout a time span of five years. Based on dyadic bivariate latent change models, we tested our assumption that self-esteem and aspects of perceived relationship conflict are negatively interrelated within individuals and between partners both within and across time. We found one actor effect of self-esteem on changes in unconstructive behavior above and beyond initial unconstructive behavior levels, supporting self-broadcasting perspectives. Moreover, we found strong support for sociometer perspectives. Actor effects highlighted the importance of perceived conflict frequency for subsequent self-esteem changes. In addition, perceived conflict styles affected both partners’ self-esteem. The results imply that perceiving conflict is a between-person process, and might be more important for the development of self-esteem than vice versa.

Study on the “Pressure Relief and Yielding Support” Joint Prevention and Control Technology for the Weak Impact Roadway in the Extremely Thick Coal Seam

Weak impact occurs during roadway excavation in some extremely thick coal seams in China. Although this hazard is not enough to destroy the roadway, it will cause fracturing and large deformation of the roadway surrounding rock, resulting in the fracturing of bolts and anchor cables and bringing great difficulties to roadway support. In the hope of solving this problem, firstly, the reason for impact occurrence in the roadway of the extremely thick coal seam is analyzed from the perspective of energy. Then, the surrounding rock fracture evolution in such a roadway is explored by means of numerical simulation, microseism, and borehole observation. Furthermore, the “pressure relief and yielding support” joint prevention and control technology is proposed and applied to Yili No. 1 Coal Mine. The field engineering application results show that the joint prevention and control technology can effectively reduce the impact energy and ensure the stability of the roadway surrounding rock in the extremely thick coal seam. The research findings can provide a theoretical foundation for the roadway support of the same type.

Managerial Challenges of Corporate Social Responsibility in Developing Countries

The aim of this chapter is to contribute to the further advancement of theoretical and empirical debate on CSR management by yielding support to the multidisciplinary and ‘context-dependent' nature of the field of managerial leadership of CSR and illustrating the various managerial orientations and attitudes of Iran's auto industry. Whilst there was very considerable evidence of the increased emphasis upon Sharia compliance mandate to regulate individual managers' personal values and orientation, there was much less evidence that this had as yet been carried through into similar behavioural and attitudinal changes at organisational and societal levels. Hence, the dominant managerial orientations toward CSR neither brought corporate behaviour up to a level where it was congruent with the prevailing Islamic cultural and societal norms nor it fulfilled the developmental promise of CSR. In a nutshell, the overall trend was incontrovertibly toward more personal/managerial use of CSR and failure to maintain a balance between (normative) developmental and instrumental CSR.

Stability of development drifts in difficult geological conditions of Starobin deposit

Extraction of the remaining reserves at the Starobinsk potassium salt deposit is associated with degradation of geological conditions as the content of clay beds in roof rocks increases with depth. The article presents the underground test data on the most promising techniques of roof support in development entries in deep-level unstable rocks in the Starobinsk potassium salt deposit. In an operating mine, various combinations of different support types and ground control approaches were tested, namely, compensation voids (slotting, racking) and long roof bolting. It is found that the maximum efficiency of development heading support is achieved with the combination of destressing headings and compensation slots. These flow charts are applicable to a depth of 860–900 m at the clay bed content of 35%. At the depths greater than 900 m and at the clay bed content higher than 35%, each underground excavation should have a specific support type. In extremely complex conditions at any depth and at the clay bed content from 35 to 60% in the roof, the support design for long underground openings with a span to 3.8 m, without slots in the sidewalls can involve roof scaling up to the roof arch (pressure arch) and installation of special-shape and expansion-type yielding support in sidewalls.

Constant Resistance and Yielding Support Technology for Large Deformations of Surrounding Rocks in the Minxian Tunnel

During the excavation of the Minxian tunnel, problems of large deformations of surrounding rocks and failure of support structures appeared frequently, which caused serious influences on construction safety and costs of the tunnel. Based on laboratory analysis of mineral composition and field investigations on deformation characteristics of the surrounding rocks, the large deformation mechanism of surrounding rocks of the tunnel was considered as water-absorbing swelling molecules of carbonaceous slate and stress-induced asymmetric structural deformations of the surrounding rocks. The structural deformations of surrounding rocks mainly include bending deformation, interlayer sliding, and crushing failure of local rock blocks. Then, a new constant resistance and yielding support technology based on the constant resistance and large deformation (CRLD) anchor cable was proposed to control large deformations of surrounding rocks. The field tests and deformation monitoring were carried out. The monitoring results showed that compared with original support measure, the surrounding rock deformations, stresses of primary supports, and permanent lining using new support technology decreased greatly. Among them, the maximum deformation of surrounding rock was only 73 mm. The effects of field application and results of deformation monitoring showed that the new support technology can effectively control large deformations of the surrounding rocks in the Minxian tunnel.