A rigorous analytical model is developed for simulating the vibration behaviors of large-diameter openended pipe piles(OEPPs)and surrounding soil undergoing high-strain impact loading.To describe the soil behavior,the...A rigorous analytical model is developed for simulating the vibration behaviors of large-diameter openended pipe piles(OEPPs)and surrounding soil undergoing high-strain impact loading.To describe the soil behavior,the soil along pile shaft is divided into slip and nonslip zones and the base soil is modeled as a fictitious-soil pile(FSP)to account for the wave propagation in the soil.True soil properties are adopted and slippage at the pile-soil interface is considered,allowing realistic representation of largediameter OEPP mechanics.The developed model is validated by comparing with conventional models and finite element method(FEM).It is further used to successfully simulate and interpret the behaviors of a steel OEPP during the offshore field test.It is found that the variation in the vertical vibrations of shaft soil along radial direction is significant for large-diameter OEPPs,and the velocity amplitudes of the internal and external soil attenuate following different patterns.The shaft soil motion may not attenuate with depth due to the soil slippage,while the wave attenuation at base soil indicates an influence depth,with a faster attenuation rate than that in the pile.The findings from the current study should aid in simulating the vibration behaviors of large-diameter OEPP-soil system under high-strain dynamic loading.展开更多
Considering the viscous damping of the soil and soil-pile vertical coupled vibration,a computational model of large-diameter pipe pile in layered soil was established.The analytical solution in frequency domain was de...Considering the viscous damping of the soil and soil-pile vertical coupled vibration,a computational model of large-diameter pipe pile in layered soil was established.The analytical solution in frequency domain was derived by Laplace transformation method.The responses in time domain were obtained by inverse Fourier transformation.The results of the analytical solution proposed agree well with the solutions in homogenous soil.The effects of the shear modulus and damping coefficients of the soil at both outer and inner sides of the pipe pile were researched.The results indicate that the shear modulus of the outer soil has more influence on velocity admittance than the inner soil.The smaller the shear modulus,the larger the amplitude of velocity admittance.The velocity admittance weakened by the damping of the outer soil is more obvious than that weakened by the damping of the inner soil.The displacements of the piles with the same damping coefficients of the outer soil have less difference.Moreover,the effects of the distribution of soil layers are analyzed.The results indicate that the effect of the upper soil layer on dynamic response of the pipe pile is more obvious than that of the bottom soil layer.A larger damping coefficient of the upper layer results in a smaller velocity admittance.The dynamic response of the pipe pile in layered soil is close to that of the pipe pile in homogenous soil when the properties of the upper soil layer are the same.展开更多
This paper aims to present a theoretical method to study the bearing performance of vertically loaded large-diameter pipe pile groups.The interactions between group piles result in different bearing performance of bot...This paper aims to present a theoretical method to study the bearing performance of vertically loaded large-diameter pipe pile groups.The interactions between group piles result in different bearing performance of both a single pile and pile groups.Considering the pile group effect and the skin friction from both outer and inner soils,an analytical solution is developed to calculate the settlement and axial force in large-diameter pipe pile groups.The analytical solution was verified by centrifuge and field testing results.An extensive parametric analysis was performed to study the bearing performance of the pipe pile groups.The results reveal that the axial forces in group piles are not the same.The larger the distance from central pile,the larger the axial force.The axial force in the central pile is the smallest,while that in corner piles is the largest.The axial force on the top of the corner piles decreases while that in the central pile increases with increasing of pile spacing and decreasing of pile length.The axial force in side piles varies little with the variations of pile spacing,pile length,and shear modulus of the soil and is approximately equal to the average load shared by one pile.For a pile group,the larger the pile length is,the larger the influence radius is.As a result,the pile group effect is more apparent for a larger pile length.The settlement of pile groups decreases with increasing of the pile number in the group and the shear modulus of the underlying soil.展开更多
Polyethylene material has some specification that makes very difficult any kind of inspection based on ultrasonic. The acoustic impedance and sound velocity in this kind of material are near to the materials commonly ...Polyethylene material has some specification that makes very difficult any kind of inspection based on ultrasonic. The acoustic impedance and sound velocity in this kind of material are near to the materials commonly used in ultrasonic wedges. Also this kind of materials are highly attenuative materials for ultrasound. To inspection of polyethylene circumferential but welds and overcome to all the problems mentioned, the especial technique of TOFD （Time of Flight Diffraction） method which employs low frequency probe and concentrate on the inspection area that longitudinal waves turn into transverse waves has been used. The purpose of inspection is determining the exact location of surface and internal welding defects. For this purpose, two separate polyethylene pipes with 10 inch in diameter, 15 mm thickness and also 25 inch diameter, 28 mm thickness, were selected. In total 40 artificial defects which involve 28 side drill holes in deferent depths and 12 surface and sub-surface notches were created. All artificially created defects were detected with very good accuracy. Unlike the conventional TOFD method which have 2 to 3 mm dead zone, by using the above method even surface notch with 0.5 mm has been detected.展开更多
During manufacturing and storage of 3PE pipes,the end PE upwarp is a common phenomenon,and the gap corrosion will be easy to produce under the condition of poor atmosphere environment, which hazard the anti-corrosion ...During manufacturing and storage of 3PE pipes,the end PE upwarp is a common phenomenon,and the gap corrosion will be easy to produce under the condition of poor atmosphere environment, which hazard the anti-corrosion quality of 3PE pipes and difficult to field coating for welded joints. The authors analyze the PE upwarp problem, and based on the analysis results the quality control measures are given for the manufacturing of 3PE pipes.展开更多
介绍了国内外耐热聚乙烯管材PE-RT树脂基本性能、结构特点,借助DSC、GPC、TREE、13C N M R等分析方法,对国内外PE-RT树脂产品结构进行剖析,对比分析这些树脂的微观结构,以及所反映的宏观力学、加工性能。试验结果表明,抚顺石化辛烯共聚...介绍了国内外耐热聚乙烯管材PE-RT树脂基本性能、结构特点,借助DSC、GPC、TREE、13C N M R等分析方法,对国内外PE-RT树脂产品结构进行剖析,对比分析这些树脂的微观结构,以及所反映的宏观力学、加工性能。试验结果表明,抚顺石化辛烯共聚耐热聚乙烯管材树脂DP800与同类产品相比,加工性能及力学性能较好。展开更多
基金support from the Exploring Youth Project of Zhejiang Natural Science Foundation (Grant No.LQ24E080009)the Key Project of Natural Science Foundation of Zhejiang Province (Grant No.LXZ22E080001)the National Natural Science Foundation of China (Grant No.52108347).
文摘A rigorous analytical model is developed for simulating the vibration behaviors of large-diameter openended pipe piles(OEPPs)and surrounding soil undergoing high-strain impact loading.To describe the soil behavior,the soil along pile shaft is divided into slip and nonslip zones and the base soil is modeled as a fictitious-soil pile(FSP)to account for the wave propagation in the soil.True soil properties are adopted and slippage at the pile-soil interface is considered,allowing realistic representation of largediameter OEPP mechanics.The developed model is validated by comparing with conventional models and finite element method(FEM).It is further used to successfully simulate and interpret the behaviors of a steel OEPP during the offshore field test.It is found that the variation in the vertical vibrations of shaft soil along radial direction is significant for large-diameter OEPPs,and the velocity amplitudes of the internal and external soil attenuate following different patterns.The shaft soil motion may not attenuate with depth due to the soil slippage,while the wave attenuation at base soil indicates an influence depth,with a faster attenuation rate than that in the pile.The findings from the current study should aid in simulating the vibration behaviors of large-diameter OEPP-soil system under high-strain dynamic loading.
基金Project(U1134207)supported by the National Natural Science and High Speed Railway Jointed Foundation of ChinaProject(B13024)supported by the "111" Program of China+1 种基金Project(BK2012811)supported by the Nature Science Foundation of Jiangsu Province,ChinaProject(NCET-12-0843)supported by the Fund for New Century Excellent Talents in Universities,China
文摘Considering the viscous damping of the soil and soil-pile vertical coupled vibration,a computational model of large-diameter pipe pile in layered soil was established.The analytical solution in frequency domain was derived by Laplace transformation method.The responses in time domain were obtained by inverse Fourier transformation.The results of the analytical solution proposed agree well with the solutions in homogenous soil.The effects of the shear modulus and damping coefficients of the soil at both outer and inner sides of the pipe pile were researched.The results indicate that the shear modulus of the outer soil has more influence on velocity admittance than the inner soil.The smaller the shear modulus,the larger the amplitude of velocity admittance.The velocity admittance weakened by the damping of the outer soil is more obvious than that weakened by the damping of the inner soil.The displacements of the piles with the same damping coefficients of the outer soil have less difference.Moreover,the effects of the distribution of soil layers are analyzed.The results indicate that the effect of the upper soil layer on dynamic response of the pipe pile is more obvious than that of the bottom soil layer.A larger damping coefficient of the upper layer results in a smaller velocity admittance.The dynamic response of the pipe pile in layered soil is close to that of the pipe pile in homogenous soil when the properties of the upper soil layer are the same.
基金supported by the Joint High Speed Railway Key Program of National Natural Science Foundation of China (Grant No.U1134207)the National Natural Science Foundation of China (Grant No.51378177)+1 种基金the Program for Excellent University Talents in New Century (Grant No.NCET-12-0843)the Fundamental Research Fund for the Central Universities (Grant No.106112014CDJZR200007)
文摘This paper aims to present a theoretical method to study the bearing performance of vertically loaded large-diameter pipe pile groups.The interactions between group piles result in different bearing performance of both a single pile and pile groups.Considering the pile group effect and the skin friction from both outer and inner soils,an analytical solution is developed to calculate the settlement and axial force in large-diameter pipe pile groups.The analytical solution was verified by centrifuge and field testing results.An extensive parametric analysis was performed to study the bearing performance of the pipe pile groups.The results reveal that the axial forces in group piles are not the same.The larger the distance from central pile,the larger the axial force.The axial force in the central pile is the smallest,while that in corner piles is the largest.The axial force on the top of the corner piles decreases while that in the central pile increases with increasing of pile spacing and decreasing of pile length.The axial force in side piles varies little with the variations of pile spacing,pile length,and shear modulus of the soil and is approximately equal to the average load shared by one pile.For a pile group,the larger the pile length is,the larger the influence radius is.As a result,the pile group effect is more apparent for a larger pile length.The settlement of pile groups decreases with increasing of the pile number in the group and the shear modulus of the underlying soil.
文摘Polyethylene material has some specification that makes very difficult any kind of inspection based on ultrasonic. The acoustic impedance and sound velocity in this kind of material are near to the materials commonly used in ultrasonic wedges. Also this kind of materials are highly attenuative materials for ultrasound. To inspection of polyethylene circumferential but welds and overcome to all the problems mentioned, the especial technique of TOFD （Time of Flight Diffraction） method which employs low frequency probe and concentrate on the inspection area that longitudinal waves turn into transverse waves has been used. The purpose of inspection is determining the exact location of surface and internal welding defects. For this purpose, two separate polyethylene pipes with 10 inch in diameter, 15 mm thickness and also 25 inch diameter, 28 mm thickness, were selected. In total 40 artificial defects which involve 28 side drill holes in deferent depths and 12 surface and sub-surface notches were created. All artificially created defects were detected with very good accuracy. Unlike the conventional TOFD method which have 2 to 3 mm dead zone, by using the above method even surface notch with 0.5 mm has been detected.
文摘During manufacturing and storage of 3PE pipes,the end PE upwarp is a common phenomenon,and the gap corrosion will be easy to produce under the condition of poor atmosphere environment, which hazard the anti-corrosion quality of 3PE pipes and difficult to field coating for welded joints. The authors analyze the PE upwarp problem, and based on the analysis results the quality control measures are given for the manufacturing of 3PE pipes.
文摘介绍了国内外耐热聚乙烯管材PE-RT树脂基本性能、结构特点,借助DSC、GPC、TREE、13C N M R等分析方法,对国内外PE-RT树脂产品结构进行剖析,对比分析这些树脂的微观结构,以及所反映的宏观力学、加工性能。试验结果表明,抚顺石化辛烯共聚耐热聚乙烯管材树脂DP800与同类产品相比,加工性能及力学性能较好。
