Large scale simulations of a rice-pile model are performed. We use moment analysis techniques to evaluate critical exponents and data collapse method to verify the obtained results. The moment analysis yields well-def...Large scale simulations of a rice-pile model are performed. We use moment analysis techniques to evaluate critical exponents and data collapse method to verify the obtained results. The moment analysis yields well-defined avalanche exponents, which show that the rice-pile model can be coherently described within a finite size scaling framework. The general picture resulting from our analysis allows us to characterize the large scale behavior of the present model with great accuracy.展开更多
According to the field test data of laterally loaded steel piles at home and abroad, an empirical formula for evaluating the modulus of subgrade reaction under static load in layered soil is proposed. The suggested fo...According to the field test data of laterally loaded steel piles at home and abroad, an empirical formula for evaluating the modulus of subgrade reaction under static load in layered soil is proposed. The suggested formula takes account of not only non-linearity of K-s with the depth but also its variation with the load. It is shown that the computed bending moments along the pile shaft and the deflection at the pile top are consistent with the measured ones.展开更多
A series of centrifuge model tests of sandy slopes were conducted to study the dynamic behavior of pile-reinforced slopes subjected to various motions.Time histories of accelerations,bending moments and pile earth pre...A series of centrifuge model tests of sandy slopes were conducted to study the dynamic behavior of pile-reinforced slopes subjected to various motions.Time histories of accelerations,bending moments and pile earth pressures were obtained during excitation of the adjusted El Centro earthquake and a cyclic motion.Under a realistic earthquake,the overall response of the pile-reinforced slope is lower than that of the non-reinforced slope.The histories of bending moments and dynamic earth pressures reach their maximums soon after shaking started and then remain roughly stable until the end of shaking.Maximum moments occur at the height of 3.5 m,which is the deeper section of the pile,indicating the interface between the active loading and passive resistance regions.The dynamic earth pressures above the slope base steadily increase with the increase of height of pile.For the model under cyclic input motion,response amplitudes at different locations in the slope are almost the same,indicating no significant response amplification.Both the bending moment and earth pressure increase gradually over a long period.展开更多
The study deals with physical modeling of a typical building frame resting on a pile group embedded in cohesive soil mass using complete three-dimensional finite element analysis. The elements of the superstructure fr...The study deals with physical modeling of a typical building frame resting on a pile group embedded in cohesive soil mass using complete three-dimensional finite element analysis. The elements of the superstructure frame and that of the pile foundation are discretized using twenty node isoparametric continuum elements. The interface between the pile and pile cap is idealized using sixteen node isoparametric surface elements. The more improved finite element mesh is used for modeling soil element as compared to the one used in the study reported in the literature. The soil elements are discretized using eight node, nine node and twelve node continuum elements. Both the elements of superstructure and substructure (i.e., foundation) including soil are assumed to remain in elastic state at all the time. The interaction analysis is carried out using sub-structure approach to attempt a parametric study. The effect of the parameter such as spacing between the piles in a group and diameter of pile is evaluated on the response of superstructure. The response includes the displacement at the top of the frame. The effect of the soil-structure interaction is observed to be significant for the type of foundation and soil considered in the present study.展开更多
Immersed cylinder piles are usually modelled as immersed carrying a tip mass and rotary moment of inertia. In this paper, an immersed cylinder pile along transversal modes of vibration are of water and structural damp...Immersed cylinder piles are usually modelled as immersed carrying a tip mass and rotary moment of inertia. In this paper, an immersed cylinder pile along transversal modes of vibration are of water and structural damping are included in the formulation. cantilever cylinder columns the equations of motion of developed. Compressibility Natural frequencies of the immersed pile are obtained from the developed equations using harmonic sweep frequency response analyses. The proposed method is applied to numerical examples, and the results obtained are shown satisfactory when compared to other numerical solutions in the literature, or to finite element solutions and experimental data.展开更多
文摘Large scale simulations of a rice-pile model are performed. We use moment analysis techniques to evaluate critical exponents and data collapse method to verify the obtained results. The moment analysis yields well-defined avalanche exponents, which show that the rice-pile model can be coherently described within a finite size scaling framework. The general picture resulting from our analysis allows us to characterize the large scale behavior of the present model with great accuracy.
文摘According to the field test data of laterally loaded steel piles at home and abroad, an empirical formula for evaluating the modulus of subgrade reaction under static load in layered soil is proposed. The suggested formula takes account of not only non-linearity of K-s with the depth but also its variation with the load. It is shown that the computed bending moments along the pile shaft and the deflection at the pile top are consistent with the measured ones.
基金Project(50639060) supported by the National Natural Science Foundation of ChinaProject(610103002) supported by the State Key Laboratory of Hydroscience and Engineering,Tsinghua University,China
文摘A series of centrifuge model tests of sandy slopes were conducted to study the dynamic behavior of pile-reinforced slopes subjected to various motions.Time histories of accelerations,bending moments and pile earth pressures were obtained during excitation of the adjusted El Centro earthquake and a cyclic motion.Under a realistic earthquake,the overall response of the pile-reinforced slope is lower than that of the non-reinforced slope.The histories of bending moments and dynamic earth pressures reach their maximums soon after shaking started and then remain roughly stable until the end of shaking.Maximum moments occur at the height of 3.5 m,which is the deeper section of the pile,indicating the interface between the active loading and passive resistance regions.The dynamic earth pressures above the slope base steadily increase with the increase of height of pile.For the model under cyclic input motion,response amplitudes at different locations in the slope are almost the same,indicating no significant response amplification.Both the bending moment and earth pressure increase gradually over a long period.
文摘The study deals with physical modeling of a typical building frame resting on a pile group embedded in cohesive soil mass using complete three-dimensional finite element analysis. The elements of the superstructure frame and that of the pile foundation are discretized using twenty node isoparametric continuum elements. The interface between the pile and pile cap is idealized using sixteen node isoparametric surface elements. The more improved finite element mesh is used for modeling soil element as compared to the one used in the study reported in the literature. The soil elements are discretized using eight node, nine node and twelve node continuum elements. Both the elements of superstructure and substructure (i.e., foundation) including soil are assumed to remain in elastic state at all the time. The interaction analysis is carried out using sub-structure approach to attempt a parametric study. The effect of the parameter such as spacing between the piles in a group and diameter of pile is evaluated on the response of superstructure. The response includes the displacement at the top of the frame. The effect of the soil-structure interaction is observed to be significant for the type of foundation and soil considered in the present study.
基金supported by the Ministry of Science and Technology of China (SLDRCE09-B-08)the National Nature Science Foundation of China (50978194 and 90915011)Kwang-Hua Fund for College of Civil Engineering,Tongji University
文摘Immersed cylinder piles are usually modelled as immersed carrying a tip mass and rotary moment of inertia. In this paper, an immersed cylinder pile along transversal modes of vibration are of water and structural damping are included in the formulation. cantilever cylinder columns the equations of motion of developed. Compressibility Natural frequencies of the immersed pile are obtained from the developed equations using harmonic sweep frequency response analyses. The proposed method is applied to numerical examples, and the results obtained are shown satisfactory when compared to other numerical solutions in the literature, or to finite element solutions and experimental data.
