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  • 1
    In: Engineering Failure Analysis, Elsevier BV, Vol. 81 ( 2017-11), p. 117-134
    Type of Medium: Online Resource
    ISSN: 1350-6307
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2017
    detail.hit.zdb_id: 2021082-6
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  • 2
    Online Resource
    Online Resource
    American Society of Civil Engineers (ASCE) ; 2018
    In:  International Journal of Geomechanics Vol. 18, No. 2 ( 2018-02)
    In: International Journal of Geomechanics, American Society of Civil Engineers (ASCE), Vol. 18, No. 2 ( 2018-02)
    Type of Medium: Online Resource
    ISSN: 1532-3641 , 1943-5622
    Language: English
    Publisher: American Society of Civil Engineers (ASCE)
    Publication Date: 2018
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  • 3
    In: Advances in Civil Engineering, Hindawi Limited, Vol. 2020 ( 2020-07-11), p. 1-12
    Abstract: Dynamic and static coupling loads (DSLs) are one of the most common stress environments in underground engineering. As the depth of a roadway increases over the life of a mine, the static load of the ground stress field increase multiplies, and the cyclic operation at the working face releases a large amount of dynamic energy. Therefore, deep roadways easily induce dynamic disasters during production. In this paper, a deep roadway numerical model was built with FLAC 3D to test the deep roadway under DSLs and was simulated with 16 different support designs. The ground stability in each support condition was examined and compared in terms of the ground deformation and scope of failure. The underlying support mechanism was further analyzed with numerical modeling in view of the deformation in the surrounding rock mass induced by variations in the support parameters. The results show that shortening the bolt spacing is an effective measure to control the deformation of surrounding rock whatever DSLs or static load. Under static load, the larger the anchoring length is, the more stable the surrounding rock is. Under DSLs, end grouting length ( S  = 600 mm) and full grouting length ( S  = 1800 mm) can effectively control the deformation of surrounding rocks and enhance the stability of surrounding rocks. The results contribute to the design of supports in the field of underground coal mines and provide a basis for determining the reasonable support scheme for roadways.
    Type of Medium: Online Resource
    ISSN: 1687-8086 , 1687-8094
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2020
    detail.hit.zdb_id: 2449760-5
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  • 4
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2018
    In:  Rock Mechanics and Rock Engineering Vol. 51, No. 1 ( 2018-1), p. 119-134
    In: Rock Mechanics and Rock Engineering, Springer Science and Business Media LLC, Vol. 51, No. 1 ( 2018-1), p. 119-134
    Type of Medium: Online Resource
    ISSN: 0723-2632 , 1434-453X
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2018
    detail.hit.zdb_id: 1476578-0
    SSG: 16,13
    SSG: 19,1
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  • 5
    In: Lithosphere, GeoScienceWorld, Vol. 2022, No. Special 11 ( 2022-06-06)
    Abstract: In order to understand the mechanism of some unconventional failures such as rockburst caused by deep rock excavation, the failure characteristics of burst-prone sandstone specimens under static and dynamic loads were studied by using the MTS816 rock mechanics testing system and the split Hopkinson pressure bar (SHPB) experimental system, as well as the effects of bedding angle and impact pressure on rock mechanical properties and failure patterns. The uniaxial compression test used a cylindrical specimen with a height of 50 mm and a diameter of 100 mm, and cylindrical specimens with height and diameter of 50 mm were adopted in the SHPB tests. The bedding angles in the tests are 0°, 45°, and 90°. In the dynamic impact test, three different impact pressures were applied to observe the magnitude of impact load on the mechanical behaviors of the burst-prone sandstone specimens. The results show that with the increase in the bedding angle, the uniaxial compressive strength firstly decreases and then increases. When the bedding angle is 45°, the uniaxial compressive strength is the lowest. The uniaxial compressive strength is highest when the bedding angle is 0°. The burst-prone sandstone specimens with different bedding angles had three different failure pattern types. Under the dynamic loading, the stress-strain curves show springback phenomenon; with the increase in impact pressure, the dynamic strength of the burst-prone sandstone specimens with each bedding angle increases; the fracture degree of the bedding sandstone specimens gradually increases. The dynamic strength of the 45° burst-prone sandstone specimen is the lowest, and it has the highest fracture degree.
    Type of Medium: Online Resource
    ISSN: 1947-4253 , 1941-8264
    Language: English
    Publisher: GeoScienceWorld
    Publication Date: 2022
    detail.hit.zdb_id: 2484996-0
    SSG: 13
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  • 6
    In: Catalysts, MDPI AG, Vol. 9, No. 4 ( 2019-04-23), p. 380-
    Abstract: During active mining operation of a gassy underground mine, large amounts of methane will be released from the mine ventilation shaft. To eliminate the harmful effects of this ventilation air methane and minimize the wastage of this potential energy resource, considerable effort has been devoted to converting this alternative fuel using catalytic combustion. This study numerically investigated the reaction performance of ventilation air methane (VAM) in helical coil tubes of various configurations utilizing a computational fluid dynamics (CFDs) approach. Several key factors affecting the catalytic combustion performance such as curvature, inlet Reynolds number, and cross-section aspect ratio were evaluated. Recalling the high cost of the catalyst used in this reaction—platinum—optimization of catalyst usage by implementing selective catalyst coating was conducted and investigated. For evaluation purposes, the reaction performance of the helical coil tube was compared to its straight counterpart. The results gave a firm confirmation of the superior performance of the helical coil tube compared to the straight one. In addition, it was found that the selective inner wall coating in the circular cross-section at a higher Reynolds number gave rise to the highest figure of merit (FoM), defined as the net energy produced per mg of catalyst platinum.
    Type of Medium: Online Resource
    ISSN: 2073-4344
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2662126-5
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  • 7
    In: Catalysts, MDPI AG, Vol. 10, No. 7 ( 2020-07-17), p. 797-
    Abstract: In a catalytic combustion of ventilation air methane, one of the key factors determining the reactor performance is the geometry of the reactor. It should be designed to provide maximum energy conversion at minimum catalyst usage and operating cost. This numerical study is conducted to investigate the catalytic combustion of ventilation air methane from a gassy underground mine in a circular straight and helical reactor channel with twisted tape insert. A three-dimensional computational fluid dynamics model which considers conservation of mass, momentum, energy, and species together with chemical reactions, and constitutive relations for species properties and reactions kinetics was developed and validated against the previously published data. The effect of several key factors affecting the catalytic combustion performance such as inlet Reynolds number, twisted tape ratio, and reactor length are evaluated to obtain the optimum reactor parameters. For evaluation purpose, the reaction performance of the studied reactors will be compared to the straight reactor without twisted tape which is set as a baseline. The results give a firm confirmation on the superior performance of the reactors with twisted tape insert as compared to those without. In addition, it is found that helical reactors generate higher net power as compared to their respective straight reactor counterpart despite having lower FoM due to larger catalyst area. Interestingly, the higher twisting ratio offers better performance in terms of net power as well as FoM. Overall, the results highlight the potential of twisted tape insert application in catalytic combustion.
    Type of Medium: Online Resource
    ISSN: 2073-4344
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2662126-5
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  • 8
    Online Resource
    Online Resource
    MDPI AG ; 2019
    In:  Applied Sciences Vol. 9, No. 9 ( 2019-05-01), p. 1824-
    In: Applied Sciences, MDPI AG, Vol. 9, No. 9 ( 2019-05-01), p. 1824-
    Abstract: In a complex stress field of underground mining or geotechnical practice, tension damage/failure in rock masses is easily triggered and dominant. Unlike metals, rocks are generally bi-modularity materials with different mechanical properties (Young’s modulus, etc.) in compression and tension. It is well established that the Young’s modulus of a rock mass is directly related to the presence of the fracture or joint, and the Young’s modulus estimation for jointed rocks and rock masses is essential for stability analysis. In this paper, the tensile properties in joint rocks were investigated by using numerical simulations based on the discrete element method. Four influencing parameters relating to the tensile properties (joint dip angle, joint spacing, joint intersection angle, and joint density) were studied. The numerical results show that there is an approximately linear relationship between the joint dip angle (α) and the joint intersection angle (β) with the tensile strength (σt), however, the changes in α and β have less influence on the Young’s modulus in tension (Et). With respect to joint spacing, the simulations show that the effects of joint spacing on σt and Et are negligible. In relation to the joint density, the numerical results reveal that the joint intensity of rock mass has great effect on Et but insignificant effect on σt.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2704225-X
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  • 9
    Online Resource
    Online Resource
    Royal Society of Chemistry (RSC) ; 2023
    In:  Journal of Materials Chemistry A Vol. 11, No. 32 ( 2023), p. 16985-16994
    In: Journal of Materials Chemistry A, Royal Society of Chemistry (RSC), Vol. 11, No. 32 ( 2023), p. 16985-16994
    Abstract: Nearly infinite chemical space and the absence of well-established structure–property relationships have considerably challenged the purposeful design of copolymers for specific applications. To address these issues, a data-driven method called a polymer genome approach was proposed for rational design of linear random copolymers and implemented for developing poly(aryl ether)s (PAEs) with high glass transition temperature ( T g ). By means of the polymer genome approach, machine learning (ML) models with high predictive accuracies and generalization abilities were established, favourable and unfavourable genes of PAEs ( i.e. , molecular fragments and physicochemical descriptors) for high T g were unearthed, and consequently molecular design strategies and mechanistic insights for developing high- T g PAEs were presented. Experimental synthesis work further verified that the T g of new PAEs which were designed following the proposed design strategies could reach 328 °C, standing in the top 1% of the current database containing 2794 PAEs, and the constructed ML models could precisely forecast the T g of new PAEs prior to synthesis, simply based on chemical structures of monomers and feed ratios. The proposed polymer genome approach opens a high-efficiency and low-cost avenue for accelerating the development of advanced PAEs and is supposed to be scalable to optimize versatile properties of other genres of linear random copolymers.
    Type of Medium: Online Resource
    ISSN: 2050-7488 , 2050-7496
    Language: English
    Publisher: Royal Society of Chemistry (RSC)
    Publication Date: 2023
    detail.hit.zdb_id: 2702232-8
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  • 10
    In: DYNA, Publicaciones DYNA, Vol. 93, No. 1 ( 2018-03-01), p. 175-181
    Abstract: The breaking of hard and thick key layers can easily cause dynamic disasters, such as rock burst and mine seismicity, and seriously threaten safe mining. To analyze the characteristics of overburden breakage and law of evolution of separation cracks under mining of hard and thick rock stratum, and to further reveal the process of the occurrence of dynamic disaster, the fracture characteristics of overlying strata during mining were analyzed via similar simulation in this study. The characteristics of surface movement and deformation before and after the breaking of hard and thick strata were then discussed based on the law of overlying rock displacement. Finally, the development law of separation fissure in hard and thick rock stratum was revealed. Results show that the key stages of overlying strata movement during mining are immediate main roof breaking; main roof cycle breaking; and hard and thick rock breaking. The hard and thick strata, which are the key strata, bear the weight of the overlying strata with small subsidence before breakage. Development of the separated stratum stops at the bottom of the hard and thick strata and maintains an unclosed state for a long time, providing the formation space for the accumulation of gas and water in the separated bed. When the hard and thick rock is broken, the subsidence of the overlying strata increases dramatically, and the separated stratum is closed rapidly, inducing gas outburst, water inrush, dramatic surface subsidence, and other disasters in the working face easily. The outcomes of this study are significant to the safe mining of working face under similar geological conditions.
    Type of Medium: Online Resource
    ISSN: 1989-1490
    Language: Unknown
    Publisher: Publicaciones DYNA
    Publication Date: 2018
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