As typical lifeline engineering systems, urban pipeline networks (UPNs) play an important role in transmission and distribution of materials or energies in modern society. Over the past years, many efforts have been devoted to the research, development and application towards intelligent operation and maintenance of UPNs in Tongji University, incorporating with the emerging artificial intelligence (AI)-based and internet of things (IoT)-based technologies. This paper presents a review on the recent advances and the important achievements pertaining to this field in Tongji University. Using multi-source data, a data-driven model for the comprehensive risk evaluation of the whole pipeline network is briefly introduced to address the limitation of the insufficiency of reliable data and demonstrated by a case study. Aiming at three major safety problems such as structural failure, leak and third-party intrusion, the advances in techniques and systems for health monitoring of urban pipelines are summarized and the various application scenarios are illustrated as well.
This study describes a developing process of lifeline earthquake engineering from historical aspects. Currently various seismic design methods have been furnished for ground shaking and for permanent ground displacement. The seismic design method for ground shaking introduces different travelling wave models in the US and in Japan. As a result, Japanese approach was developed by actively taking into account the slippage effect in order to solve the inelastic response of the pipeline for a severe earthquake. The seismic design method for permanent ground displacement, on the other hand, prepared various numerical modeling and database in the US, while the simplified design formula for ground displacement was furnished in the seismic design guidelines in Japan. The detail design formula for liquefied ground settlement and fault displacement are expressed in this study. Various approaches of the performance-based seismic design method are compared among EU, the US and Japan. Unfortunately, the design method in Japan does not show the safety target in the guidelines. Then a simple evaluation approach to obtain the safety index is proposed herein. The different performance of two actual pipeline systems is compared, in which one pipeline system demonstrated a good performance for 2011 East Japan Great Earthquake, and the other did not. In state-of-the-art study, the seismic experiments and design method of expansion joints are described, because the ultimate limit performance of the expansion joints has not been explicit, although many seismic damages have occurred at the locations of vulnerable expansion joints.
Buried prestressed concrete cylinder pipes (PCCPs) are subjected to the combined effects of soil cover loads, internal water pressure, and additional loads. However, there is scarce research on their mechanical performance under complex service conditions after being buried. In this study, 3D nonlinear finite element (FE) models of PCCPs and soils, along with fluid models, were developed using ABAQUS and FLUENT, respectively. Fluid–solid coupling numerical simulations of PCCPs with broken wires under complex service conditions were conducted using the MpCCI platform. The study focused on investigating the mechanical behaviors of PCCP pipes with broken wires, aiming to determine the effects of different numbers and locations of broken wires, as well as the magnitude of operating water pressure. The results shows that the number of broken wires is a crucial factor affecting the mechanical behaviors of the PCCPs; the dynamic variation of internal pressure within the pipe can cause further damage to PCCPs with pre-existing defects; when wire breakage occurs alone the springline of the PCCPs, the outer concrete core exhibited a tendency to crack before the inner concrete core. Conversely, when wire breaks occurred at the crown and invert, the inner concrete core cracked before the outer concrete core. These results provide valuable insights into the behavior of PCCPs under complex conditions and contribute to the understanding of their structural integrity. The findings can aid in the development of improved design and maintenance strategies for PCCPs, ensuring their reliable performance in underground applications.
Rainfall-induced slope failures frequently occurs in many urban areas around the world especially due to the impact of the global warming. Some slope failures result in casualties that have negative impacts on urban sustainability. The slope failures are normally observed near slope surface within the unsaturated zone above the groundwater table. Hence, it is important to incorporate the unsaturated soil mechanics principles in analysing the slope stability during rainfall. This study focuses predominantly on the regional stability analyses of residual soils within the Jurong Formation and Bukit Timah Granite in Singapore. The objective of the study is to develop slope susceptibility map as part of preventive measures against extreme rainfall conditions. The slope susceptibility map was evaluated using 2-D numerical analyses of slopes with historical failure. The recently developed sustainable retaining structure system, GeoBarrier System (GBS) is investigated to understand its suitability as a preventive measure for critical slopes with high risk as identified from the slope susceptibility map. Using Transient Rainfall Infiltration (TRIGRS) and Grid-Based Regional Slope Stability Analysis (Scoops3D), the pore-water pressure distributions and factors of safety (FS) within each zone are determined. The results from slope susceptibility maps and 2-D numerical analyses are consistent. Moreover, the incorporation of GeoBarrier System on the critical slope is demonstrated to be an effective slope stabilization measure based on the numerical simulations of two-dimensional analyses.
The hospital is one of the commercial buildings with the most complex and challenging operational management stage, and digital twin has been an important tool to improve the efficiency and quality of hospital operation management (HOM). As the largest developing country in the world, China has realized the potential of digital twin adoption in HOM, but the existing studies lack the systematic analysis of the determinants and the clarifying of their interrelationship. To fill these knowledge gaps, this paper employed Technology-Organization-Environment framework to sort out 12 determinants, and used DEMATEL-ISM method to analyze the interrelationships of determinants. The results showed that government policy was the determinant with the highest centrality degree and had the highest positive causality degree, while reliability was had lowest negative causality degree. User requirement was the only determinant at the root level, while the other three determinants under the environment dimension were at the deep and middle levels. The determinants under organizational dimension were located in the middle level and shallow level, and the determinants under technical dimension were all located in shallow level. Finally, three implications were put forward, including investigating user requirements for digital twin, leveraging support in the external environment and improving adoption readiness within the hospital. This study would not only enrich the academic framework in the field of HOM, but also provide the guidance for adopting digital twin in HOM in China and other similar economies around the world.
In today's rapidly urbanizing world, there is dire need for adopting the principles of green/ sustainable built-environment so as to mitigate the ill effects of environmental degradation and climate change. However, demand for housing is on rise in developing countries like India, where sizeable population, especially the low-income strata, still lacks decent quality structurally safe housing. Extensive use of concrete and steel in construction over more than a century has led to detrimental environmental effects such uncontrolled release of greenhouse gases/ pollutants, deforestation and erosion, leading to now visible outcomes of climate change. Bamboo, on other hand provides a sustainable alternative to concrete and steel as a building material since it absorbs the atmospheric carbon dioxide, produces more oxygen than timber producing trees and is a lightweight and renewable building material. Unlike timber, it matures in four to five years and being grass family, is replenishable in nature. However, from structural point of view, the main drawback of bamboo culm is its large slenderness ratio, which renders it weak in resisting bending and compressive loads. This paper presents an alternate structural system utilizing fibre reinforced bamboo composite (FRBC) to overcome the structural deficiency of a single shoot bamboo and build a prototype structure after detailed laboratory evaluation and structural analysis. Structural elements made from FRBC are utilized for fabricating a prototype 3D frame structure, measuring about 24 m2 in plan, representing a modular unit amenable to horizontal and vertical expansion. Eco-friendly materials like cow-dung based bricks and mortar, which offer net zero additional carbon dioxide emissions and circumvent reliance on cement and river sand, have been utilized as masonry infills after structural evaluation. The built structure provides a proof-of-concept demonstration of the feasibility of using bamboo and cow-dung, sustainable building materials, for achieving a structurally safe built-environment. The technology is especially suitable for countries like India which are endowed with tropical climatic conditions. By adopting such environmentally friendly alternatives, the construction industry can create a healthier environment while addressing housing and infrastructure needs in sustainable manner.
Long term performance of urban metro tunnels requires that the tunnel structure maintains not only a sound structural state, i.e., free from significant damages, but also a minimal change in the physical shape. Over-deformation can cause structural damage but more importantly can affect the safe operation of the metro lines, therefore is a primary target of monitoring and intervention where it becomes necessary. This paper presents an overview of recent developments in field monitoring and assessment of metro tunnels in soft soil concerning over-deformation. In particular, the over-deformation of shield tunnel rings due to nearby construction activities, especially deep excavation, and its rectification using grout treatment is discussed on the basis of relevant field experiment and numerical modelling reported in recent publications. Key considerations in the development of a Material Point Method (MPM) based numerical modelling framework for simulating explicitly the grouting operations are highlighted, and the general performance of the numerical model is examined with reference to the field test data and characteristic parametric observations. Further research needs in terms of more rigorous assessment and design of grouting treatment, in conjunction with the continued development of numerical modelling capabilities, are discussed.
Transportation systems serve as a crucial foundation for maintaining the normal operation of cities and satisfying the requirements of public life. With the development of next-generation information technologies, automated driving technologies have brought new opportunities to improve the performance of traffic systems and the intelligence level of cities. Currently, significant research efforts have been conducted to develop automated driving systems in three major industries, i.e., automobile, roadway, and telecommunication. However, the collaboration and integration of automated driving systems among automobile, roadway, and telecommunications are still lacking, especially for collaborative development of system architecture and objectives. To address the need, this study first proposes a system architecture of vehicle–road-cloud collaborative automated driving system (VRC-CADS). Three levels of collaborative development, i.e., collaborative sensing, collaborative decision-making, and collaborative control, are designed for the VRC-CADS. Based on that, the typical scenarios of automated driving for each level of the system are further defined and interpreted. Moreover, feasible and systematic suggestions for the collaborative development of the VRC-CADS are provided, considering the cross-cutting collaboration among government agencies, academia, and industry. The proposed system architecture of the VRC-CADS will facilitate the optimization of urban lifelines and the evolution of intelligent cities.
Indoor and underground space positioning and navigation systems are important infrastructure for urban lifeline construction. With the development of 5G communication technology, artificial intelligence, intelligent construction, and other technologies, autonomous mobile terminals have become the main application subjects, and the requirements for accuracy and ubiquity of indoor positioning technology are also increasing. Two main indoor positioning technologies, sensor based and RF signal based are introduced, basic concepts of new visible light communication positioning technology are discussed, and in-depth results on non-imaging and imaging positioning methods are presented in this article. We propose a pose-assisted imaging positioning method applied in the 11 m × 8 m × 3.5 m room, which is based on visible light communication. This test shows that this method can achieve the positioning results with a plane positioning error less than 5 cm and the height error less than 6 cm by using low-cost sensors. Visible light positioning technology provides a cost-effective and convenient new solution for indoor positioning, simultaneously solving the integration problem of communication and positioning. It can provide positioning technology supporting the construction of urban lifelines in enclosed spaces.