In this study,2D and 3D soil arching phenomena associated with piled embankments were evaluated by performing a series of discrete numerical analyses using the particle flow code(PFC3D)software.After validating the mi...In this study,2D and 3D soil arching phenomena associated with piled embankments were evaluated by performing a series of discrete numerical analyses using the particle flow code(PFC3D)software.After validating the micro-parameters with experimental results,we compared the stress-displacement distribution,force chain evolution,maximum vertical displacement of particles,and deformation characteristics induced by 2D and 3D arching effects.Additional analyses were carried out to understand the influence of the fill height,pile clear spacing,friction coefficient,and porosity on soil arching with respect to the stress concentration ratio(SCR)and settlement along the elevation at various sections.The numerical results indicated that a plane soil arch in a 2D embankment overestimates the degree of load transfer and underestimates the settlement at the crest and within the embankment along the elevation in a 3D embankment.A lower equal settlement plane can be found in a 2D embankment.Furthermore,an increase of fill height and friction angle,and a decrease of pile clear spacing and porosity can help to improve the degree of reduction in load transfer and settlement in both 2D and 3D embankments.However,for partially mobilized soil arching in the 3D condition,the increase of fill height reduces the settlement of soils mainly in the portion above the square subsoil area,but has less influence over the portion above the rectangular subsoil area.展开更多
We study a single-server queueing system with state-dependent arrivals and general service distribution, or simply M（n）/G/1/K, where the server follows an N policy and takes multiple vacations when the system is emp...We study a single-server queueing system with state-dependent arrivals and general service distribution, or simply M（n）/G/1/K, where the server follows an N policy and takes multiple vacations when the system is empty. We provide a recursive algorithm using the supplementary variable technique to numerically compute the stationary queue length distribution of the system. The only input requirements are the Laplace-Stieltjes transforms of the service time distribution and the vacation time distribution, and the state-dependent arrival rate. The computational complexity of the algorithm is O（K^3）.展开更多
基金Project supported by the National Natural Science Foundation of China(No.41772289)。
文摘In this study,2D and 3D soil arching phenomena associated with piled embankments were evaluated by performing a series of discrete numerical analyses using the particle flow code(PFC3D)software.After validating the micro-parameters with experimental results,we compared the stress-displacement distribution,force chain evolution,maximum vertical displacement of particles,and deformation characteristics induced by 2D and 3D arching effects.Additional analyses were carried out to understand the influence of the fill height,pile clear spacing,friction coefficient,and porosity on soil arching with respect to the stress concentration ratio(SCR)and settlement along the elevation at various sections.The numerical results indicated that a plane soil arch in a 2D embankment overestimates the degree of load transfer and underestimates the settlement at the crest and within the embankment along the elevation in a 3D embankment.A lower equal settlement plane can be found in a 2D embankment.Furthermore,an increase of fill height and friction angle,and a decrease of pile clear spacing and porosity can help to improve the degree of reduction in load transfer and settlement in both 2D and 3D embankments.However,for partially mobilized soil arching in the 3D condition,the increase of fill height reduces the settlement of soils mainly in the portion above the square subsoil area,but has less influence over the portion above the rectangular subsoil area.
基金partially supported by National Science Foundation under DMI-0200306supported in part by a grant from National Natural Science Foundation of China under No.70228001.
文摘We study a single-server queueing system with state-dependent arrivals and general service distribution, or simply M（n）/G/1/K, where the server follows an N policy and takes multiple vacations when the system is empty. We provide a recursive algorithm using the supplementary variable technique to numerically compute the stationary queue length distribution of the system. The only input requirements are the Laplace-Stieltjes transforms of the service time distribution and the vacation time distribution, and the state-dependent arrival rate. The computational complexity of the algorithm is O（K^3）.
