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    Tytuł:
    Experimental study on the joint application of innovative techniques for the improved drivage of roadways at depths over 1 km: a case study
    Autorzy:
    Zhang, Wei
    Tang, Jia-Jia
    Zhang, Dong-Sheng
    Zhang, Lei
    Sun, Yuyan
    Zhang, Wei-Sheng
    Powiązania:
    https://bibliotekanauki.pl/articles/219958.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    pomiar naprężeń
    wiercenie
    piaskowanie
    odkształcenie
    roadways at depth over 1 km
    in-situ stress measurements
    efficient drivage
    rapid drilling and blasting
    deformation control of SRR
    industrial test
    Opis:
    Finding effective ways to efficiently drive roadways at depths over 1 km has become a hotspot research issue in the field of mining engineering. In this study, based on the local geological conditions in the Xinwen Mining Area (XMA) of China, in-situ stress measurements were conducted in 15 representative deep roadways, which revealed the overall tectonic stress field pattern, with the domination of the horizontal principal stresses. The latter values reached as high as 42.19 MPa, posing a significant challenge to the drivage work. Given this, a comprehensive set of innovative techniques for efficiently driving roadways at depths over 1 km was developed, including (i) controlled blasting with bidirectional energy focusing for directional fracturing, (ii) controlled blasting with multidirectional energy distribution for efficient rock fragmentation, (iii) wedge-cylinder duplex cuts centered on double empty holes, and (iv) high-strength supports for deep roadways. The proposed set of techniques was successfully implemented in the –1010 west rock roadway (WRR) drivage at the Huafeng Coal Mine (HCM). The improved drivage efficiency was characterized by the average and maximum monthly advances of 125 and 151 m, respectively. The roadway cross-sectional shape accuracy was also significantly improved, with the overbreak and underbreak zones being less than 50 mm. The deformation in the surrounding rock of roadway (SRR) was adequately controlled, thus avoiding repeated maintenance and repair. The relevant research results can provide technical guidance for efficient drivage of roadways at depths over 1 km in other mining areas in China and worldwide.
    Źródło:
    Archives of Mining Sciences; 2020, 65, 1; 159-178
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Micromechanical Properties and Stress Measurements with Diffraction Methods
    Autorzy:
    Gadalińska, E.
    Baczmański, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/97807.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
    Tematy:
    X-ray diffraction
    stress measurements on riveted samples
    duplex steel
    composites
    stress measurements during in-situ tensile test
    stress concentarion tensor
    necking phenomenon
    Opis:
    Diffraction methods are commonly used for the determination of the elastic lattice deformation and distortion from the displacement and broadening of the diffraction peak. These methods enable researchers to measure stresses and elastic properties of polycrystalline materials. The main advantages of diffraction methods are their non-destructive character and the possibility of macrostress and microstress analysis for multiphase and anisotropic materials. Measurements are performed selectively only for crystallites contributing to the measured diffraction peak, i.e. for the grains having lattice orientations for which the Bragg condition is satisfied. When several phases are present in the sample, measurements of separate diffraction peaks allow for the behaviour of each phase to be investigated independently. This method can be applied without any limitations to flat specimens. Numerical calculations of residual stresses around the rivets imply a very high stress gradientin the case of tangential stresses as well in the case of radial stresses. Attempting to verify these predictions, the residual stress measurements with an X-ray diffractometer were performed on riveted samples after the riveting process. In addition, complementary measurements of strain values with strain gauges during the riveting process were performed as well as the finite elements modelling. The aim of these measurements was to determine the stress values around the rivets and to compare results obtained with different techniques. On the other hand, the multi-scale crystallographic model of elastoplastic deformation is very convenient for the study of elastoplastic properties in microscopic and macroscopic scales. Comparison of experimental data with model predictions allows us to understand the physical phenomena that occur during a sample's deformation at the level of polycrystalline grains. Moreover, the micro and macro parameters of elastoplastic deformation can be experimentally established. It should be stated that the characterisation of the residual stress field and elastic properties is important in the study of the mechanical behaviour of polycrystalline materials, including plasticity and damage phenomena. In this work, a new analysis method of neutron diffraction results obtained during in-situ tensile load is proposed and tested. The methodology is based on the measurements of lattice strains during in-situ tensile testing for several hkl reflections and for different orientations of the sample with respect to the scattering vector. As the result, the full stress tensor for preferred texture orientations in function of the applied stress can be determined using the crystallite group method. The experimental data are presented and compared with the self-consistent model calculations performed for groups of grains selected by different hkl reflections.
    Źródło:
    Fatigue of Aircraft Structures; 2013, 5; 18-39
    2081-7738
    2300-7591
    Pojawia się w:
    Fatigue of Aircraft Structures
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-2 z 2

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