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  • 11
    In: Advances in Civil Engineering, Hindawi Limited, Vol. 2020 ( 2020-12-16), p. 1-11
    Abstract: Desert sand is one of the current research hotspots in alternative materials for concrete aggregates. In the process of practical application, compressive strength is an essential prerequisite for studying other properties. Based on the current research situation, a prediction technology of compressive strength of desert sand concrete (DSC) is proposed based on an artificial neural network (ANN) and a particle swarm optimization (PSO). The technology is a prediction model that adjusts the network architecture by using the PSO method based on the ANN optimization model. Water-binder ratio, sand ratio, replacement rate of desert sand, desert sand type, fly ash content, silica fume content, air content, and slump were selected as the neural network’s inputs. The compressive strength data of 118 different combinations of influencing variables were tested to establish the dataset. The results show that the PSO method is efficient for the ANN in DSC compressive strength research. Furthermore, referring to this method, DSC is applied to the shotcrete of tunnels in construction engineering successfully, and the dust particle content during construction is evaluated.
    Type of Medium: Online Resource
    ISSN: 1687-8094 , 1687-8086
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2020
    detail.hit.zdb_id: 2449760-5
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  • 12
    Online Resource
    Online Resource
    Hindawi Limited ; 2021
    In:  Advances in Civil Engineering Vol. 2021 ( 2021-6-22), p. 1-15
    In: Advances in Civil Engineering, Hindawi Limited, Vol. 2021 ( 2021-6-22), p. 1-15
    Abstract: Aiming at the cyclic impact deformation and failure of tunnel surrounding rock under shear stress, a self-developed rotation-impact simulation test platform was used to determine the number of failures, stress-strain curves, and energy in the process of cyclic impact failure. The failure process of rock under different impact velocities and shear stresses has been systematically studied. Results show that, under the same impact speed, the shear stress will increase with the increase in the rotation speed, but an upper limit will exist. When the rotation speed reaches this upper limit, the shear stress will no longer increase. The presence of shear stress will reduce the number of impacts required for rock failure. When the impact speed is 7.2 m/s, the number of impacts at the maximum rotation speed is 60% of the static state. When the impact velocity is 16.8 m/s, this value is only 33.3%. At the same impact velocity, the stress-strain curves under different rotation speeds do not change significantly, but with the increase in the rotation speed, the slope of the elastic stage of the stress-strain curve gradually decreases, and the corresponding stress of the rock sample decreases when the maximum strain is reached. With the increase in shear stress, the crushing specific energy required for rock failure gradually decreases. The greater the impact velocity, the more obvious the impact of shear stress on energy dissipation. In the tunnel process, when the surrounding rock is subjected to impact loads from different directions, only the axial strain analysis will have certain safety hazards, and timely support and reinforcement work are required.
    Type of Medium: Online Resource
    ISSN: 1687-8094 , 1687-8086
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2021
    detail.hit.zdb_id: 2449760-5
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  • 13
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2019
    In:  Arabian Journal of Geosciences Vol. 12, No. 13 ( 2019-7)
    In: Arabian Journal of Geosciences, Springer Science and Business Media LLC, Vol. 12, No. 13 ( 2019-7)
    Type of Medium: Online Resource
    ISSN: 1866-7511 , 1866-7538
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2438771-X
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  • 14
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2022
    In:  Arabian Journal of Geosciences Vol. 15, No. 6 ( 2022-03)
    In: Arabian Journal of Geosciences, Springer Science and Business Media LLC, Vol. 15, No. 6 ( 2022-03)
    Type of Medium: Online Resource
    ISSN: 1866-7511 , 1866-7538
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2438771-X
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  • 15
    Online Resource
    Online Resource
    Hindawi Limited ; 2018
    In:  Advances in Materials Science and Engineering Vol. 2018 ( 2018-06-20), p. 1-11
    In: Advances in Materials Science and Engineering, Hindawi Limited, Vol. 2018 ( 2018-06-20), p. 1-11
    Abstract: The 28 days cured cement mortar samples were soaked in HCl (pH = 1 and 2) and H 2 O (pH = 7) solutions for 90 days. By monitoring the ion concentration of H + and Ca 2+ and measuring the changes in weight loss, longitudinal wave velocity, and uniaxial compressive strength values of the corroded mortar, the physicochemical and mechanical properties of the mortar specimens were studied. Experimental results indicate that the process of the mortar sample subjected to HCL erosion has apparent stage characteristics. In the initial stage of corrosion, the chemical reaction increased the porosity of the specimen, which leads to the decrease of longitudinal wave velocity of the samples. At the same time, the corrosion solution continuously penetrates into the mortar pore system, which leads to the increase of the mass, and it is considered that the diffusion process plays a leading role during this period. Moreover, the colloidal compounds generated by the chemical reaction can not only fill the pore space but also block the continuous reaction, which led to the increase of the longitudinal wave velocity of the specimen. With the prolonging of corrosion time and infiltration path, the pH value and the concentration of Ca 2+ tend to be stable, the diffusion action is weakened, and the chemical reaction is continuous, which led to the decrease of the mass and wave velocity gradually. It is considered that the chemical reaction plays a leading role in this process. Based on the induction and analysis of the test results, a generalized porosity model regarding the increase of the porosity and the decrease of effective bearing area of the mortar sample was proposed. The relation between the uniaxial compressive strength and the corrosion time of the corroded mortar is deduced, and the unknown parameters are determined based on the regression analysis of the test data.
    Type of Medium: Online Resource
    ISSN: 1687-8434 , 1687-8442
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2018
    detail.hit.zdb_id: 2501025-6
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