A simplified approach is presented to analyze the single pile settlement in multilayered soil. First, a fictitious soil-pile model is employed to consider the effect of layered soil beneath pile toe on pile settlement...A simplified approach is presented to analyze the single pile settlement in multilayered soil. First, a fictitious soil-pile model is employed to consider the effect of layered soil beneath pile toe on pile settlement behavior. Two approximation methods are proposed to simplify the nonlinear load transfer function and simulate the nonlinear compression of fictitious soil-pile, respectively. On this basis, an efficient program is developed. The procedures for determining the main parameters of mathematical model are discussed. Comparisons with two well-documented field experimental pile loading tests are conducted to verify the rationality of the present method. Further studies are also made to evaluate the practicability of the proposed approach when a soft substratum exists, and the results suggest that the proposed method can provide a constructive means for assessing the settlement of a single pile for use in engineering design.展开更多
This paper presents the results of an experimental survey on the potential application of DARC (dry asphalt rubber concrete) in rail superstructure, within sub-ballast layers by measuring its damping and mechanical ...This paper presents the results of an experimental survey on the potential application of DARC (dry asphalt rubber concrete) in rail superstructure, within sub-ballast layers by measuring its damping and mechanical properties. Based on the environmental friendly point of view the DARC has the significant advantage as the backfill material of sub-ballast layer because the rubber comes from the waste tires of truck and its usage can results a significant recycling of non-biodegradable wastes. After a preliminary mix-design of several DARCs, with different rubber content that confirmed by using the Marshall test, the stiffness modulus and damping ratio both of a standard bituminous mixture and of dry asphalt rubber concrete with a rubber content equal to 1.5% were determined using the four points bending device. The experimental results were compared and a numerical analysis by means of a 2D lumped mass model was developed in order to evaluate the different performance within the rail superstructure in terms both of the deflection and of the pressure on sub-grade. Both the results on the mechanical and dissipative properties of the DARC and the mechanical behavior of the correlate rail superstructure encourage the authors to continue the research on the application of such material for sub-ballast layers.展开更多
In this study, the relationship between the neutral components (N2 and 02) in the E-region of the ionosphere (at 110 km altitude) for the Singapore (01.23 N; 103.55 E) station in the equatorial region and the FI...In this study, the relationship between the neutral components (N2 and 02) in the E-region of the ionosphere (at 110 km altitude) for the Singapore (01.23 N; 103.55 E) station in the equatorial region and the FI0.7 solar flux and z-component of Interplanetary Magnetic Field (IMF-Bz) was investigated. This relationship was determined by means of statistical multiple regression model. As a result, it was observed that the changes in F10.7 solar flux and IMF-Bz were inversely proportional to the changes in N2 and 02. 92% and 83% of changes in N2 and O2 were found to be explained by F10.7 solar flux and IMF-Bz, respectively. When the F10.7 solar flux is changed by 1 s.f.u., it causes a decrease of 2.61×10TM m-3 in N2 and 2.96×1014 m-3 in O2. Change of I nT in IMF-Bz causes a decrease of 9.95× 1015 m-3 in N2 and 1.69× 1015 m-3 in O2.展开更多
基金Project(51378464) supported by the National Natural Science Foundation of China
文摘A simplified approach is presented to analyze the single pile settlement in multilayered soil. First, a fictitious soil-pile model is employed to consider the effect of layered soil beneath pile toe on pile settlement behavior. Two approximation methods are proposed to simplify the nonlinear load transfer function and simulate the nonlinear compression of fictitious soil-pile, respectively. On this basis, an efficient program is developed. The procedures for determining the main parameters of mathematical model are discussed. Comparisons with two well-documented field experimental pile loading tests are conducted to verify the rationality of the present method. Further studies are also made to evaluate the practicability of the proposed approach when a soft substratum exists, and the results suggest that the proposed method can provide a constructive means for assessing the settlement of a single pile for use in engineering design.
文摘This paper presents the results of an experimental survey on the potential application of DARC (dry asphalt rubber concrete) in rail superstructure, within sub-ballast layers by measuring its damping and mechanical properties. Based on the environmental friendly point of view the DARC has the significant advantage as the backfill material of sub-ballast layer because the rubber comes from the waste tires of truck and its usage can results a significant recycling of non-biodegradable wastes. After a preliminary mix-design of several DARCs, with different rubber content that confirmed by using the Marshall test, the stiffness modulus and damping ratio both of a standard bituminous mixture and of dry asphalt rubber concrete with a rubber content equal to 1.5% were determined using the four points bending device. The experimental results were compared and a numerical analysis by means of a 2D lumped mass model was developed in order to evaluate the different performance within the rail superstructure in terms both of the deflection and of the pressure on sub-grade. Both the results on the mechanical and dissipative properties of the DARC and the mechanical behavior of the correlate rail superstructure encourage the authors to continue the research on the application of such material for sub-ballast layers.
文摘In this study, the relationship between the neutral components (N2 and 02) in the E-region of the ionosphere (at 110 km altitude) for the Singapore (01.23 N; 103.55 E) station in the equatorial region and the FI0.7 solar flux and z-component of Interplanetary Magnetic Field (IMF-Bz) was investigated. This relationship was determined by means of statistical multiple regression model. As a result, it was observed that the changes in F10.7 solar flux and IMF-Bz were inversely proportional to the changes in N2 and 02. 92% and 83% of changes in N2 and O2 were found to be explained by F10.7 solar flux and IMF-Bz, respectively. When the F10.7 solar flux is changed by 1 s.f.u., it causes a decrease of 2.61×10TM m-3 in N2 and 2.96×1014 m-3 in O2. Change of I nT in IMF-Bz causes a decrease of 9.95× 1015 m-3 in N2 and 1.69× 1015 m-3 in O2.