Sustainable urban development relies on forward-looking infrastructure development. As an emerging infrastructure system that incorporates green technologies, the Metro-based Underground Logistics System (M-ULS) enables sustainable transportation of passengers and freight within cities collaboratively by sharing rail transit network facilities. M-ULS can effectively save non-renewable energy and reduce pollution to the ecological environment, and the comprehensive benefits of the system make an outstanding contribution to sustainable urban development. The purpose of this study is to provide a systematic review of M-ULS based on different perspectives and to present the development of the M-ULS network integration concept. By employing bibliometric analysis, the four dimensions of M-ULS related literature are statistically analyzed to discover the knowledge structure and research trends. Through thematic discussions, a development path for developing the concept of M-ULS network integration was established. The main findings of this study are summarized as follows: (i) A comparative analysis shows that the metro system has a high potential for freight use; (ii) Improvements in metro freight technologies are conducive to urban economy, environment, and social sustainability; (iii) Network expansion is an inevitable trend for implementing underground logistics based on the metro; (iv) The interaction among public sectors, metro operators, logistics corporations, and users plays a critical role in promoting the development of M-ULS. (v) It is worth mentioning that the planning of green infrastructure should fully consider its comprehensive contribution to the sustainable development of the city. This study visualizes the current status and hotspots of M-ULS research. It also discloses frontier knowledge and novel insights for the integrated planning and operations management of metro and urban underground freight transportation.
In recent years, the construction of tunnels and subways has increased significantly. Current researches related to the underground engineering always focus on quasi-static force analysis of semi-infinite media, thus it is of great significance to analysis the borehole pressure during tunnel construction. In this paper, a finite cavity expansion model in finite diameter geological media is proposed considering the influence of finite radial extent of geological media and drilling velocity, and theoretical and computational analysis is carried out.
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