This paper proposes an empirical formula to estimate the shear strength of hydraulic expansion rockbolts.The field experimental results were obtained from eleven pullout tests to evaluate the results computed by the p...This paper proposes an empirical formula to estimate the shear strength of hydraulic expansion rockbolts.The field experimental results were obtained from eleven pullout tests to evaluate the results computed by the proposed formula.It was found that shear resistance of hydraulic expansion rockbolts significantly depends on the uniaxial compressive strength and elastic modulus of rock,with high correlation coefficients of 0.7651 and0.8587,respectively.The developed formula enables estimation of the maximum pullout load in an analytical process without pullout tests in the field.Conversely,due to the poor interlocking at the initial pullout load,the measured displacements were higher than the estimated ones.To reduce the interlocking effects between bolt and rock,we recommend preloading of 29.4 kN.Preload allows reducing the distance between the measured and estimated displacement and making two load-displacement curves practically identical with marginal differences of 1.1 to 1.5 mm at the maximum pullout load.展开更多
W/ Cu functionally gradient materials （FGMs） containing 1% La2O3 and 1% TiC were prepared using graded sintering under tdtra-high pressure （GSUHP）. The specimens have been found to exhibit low porosity （11.57% an...W/ Cu functionally gradient materials （FGMs） containing 1% La2O3 and 1% TiC were prepared using graded sintering under tdtra-high pressure （GSUHP）. The specimens have been found to exhibit low porosity （11.57% and 11.35%, respectively）. Shearing strength of the specimens between layers is good. Moreover, the specimens have still demonstrated good performance in testing thermal-shock resistance. When power density of laser is 200MWm^-2, the specimens have been tested for thermal-shock resistance （1000 times）; the specimens that contained 1%La2O3 were not subjected to damage, whereas those that contained 1%TiC began to crack. Finally, effect of additives on thermal-shock resistance was also preliminarily discussed.展开更多
基金supported by 2016 Hongik University Research Fund and the Convergence R&D program of MSIP/NST[Convergence Research-14-2-ETRI,Development of Internet of Things(IoT)-based Urban Underground Utility Monitoring and Management System]
文摘This paper proposes an empirical formula to estimate the shear strength of hydraulic expansion rockbolts.The field experimental results were obtained from eleven pullout tests to evaluate the results computed by the proposed formula.It was found that shear resistance of hydraulic expansion rockbolts significantly depends on the uniaxial compressive strength and elastic modulus of rock,with high correlation coefficients of 0.7651 and0.8587,respectively.The developed formula enables estimation of the maximum pullout load in an analytical process without pullout tests in the field.Conversely,due to the poor interlocking at the initial pullout load,the measured displacements were higher than the estimated ones.To reduce the interlocking effects between bolt and rock,we recommend preloading of 29.4 kN.Preload allows reducing the distance between the measured and estimated displacement and making two load-displacement curves practically identical with marginal differences of 1.1 to 1.5 mm at the maximum pullout load.
文摘W/ Cu functionally gradient materials （FGMs） containing 1% La2O3 and 1% TiC were prepared using graded sintering under tdtra-high pressure （GSUHP）. The specimens have been found to exhibit low porosity （11.57% and 11.35%, respectively）. Shearing strength of the specimens between layers is good. Moreover, the specimens have still demonstrated good performance in testing thermal-shock resistance. When power density of laser is 200MWm^-2, the specimens have been tested for thermal-shock resistance （1000 times）; the specimens that contained 1%La2O3 were not subjected to damage, whereas those that contained 1%TiC began to crack. Finally, effect of additives on thermal-shock resistance was also preliminarily discussed.
