Abstract Aiming at the problem of urban water supply network protection under terrorist attack, a new comprehensive value evaluation method for important nodes of water supply network is proposed. Combined with the characteristics of terrorist attacks, Epanet and Aloha were used to simulate the changes in the efficiency of the water supply network and the consequences of secondary disasters after the node was destroyed, and a comprehensive value evaluation model based on the node’s own value, system value and indirect value was constructed. Taking an urban water supply network in Hubei Province as an example, the results can get the following conclusions: ①Compared with the buried water pipeline, the water supply plant as the source of the urban water supply network is the key target of terrorists; ②the calculation results show the comprehensive value of different water plants The gap is huge, and the comprehensive value of water plant 3 is nearly 5 times that of water plant 4; ③ the greater the comprehensive value of the water plant, the greater the terrorist attack revenue and the higher the probability of attack. Therefore, when responding to terrorist attacks, the comprehensive value should be High water plants provide more protection resources.
The development of urban underground space can increase the green area of a city and have a positive impact on urban microclimate. However, the negative impacts of urban under-ground space development on the urban microclimate are rarely considered and analyzed. In this study, we focus on analyzing the impact of the development of underground commercial streets under determinant urban form on urban microclimate using outdoor CO concentrations as the evaluation index. In this regard, it was possible to quantitatively evaluate the influences of various development factors (e.g., development intensity of underground commercial streets; location and height of shaft exhaust; and various ground-greening configurations of transverse and vertical trees, large and small shrubs, and grasses) on the outdoor CO concentration. The results showed that higher development intensity increases outdoor CO concentration and its range of effects. Properly increasing the height of shaft exhausts, choosing a dispersed layout for shaft exhausts, and planting large shrubs on the ground in the development area of underground commercial streets can effectively reduce the impact of underground commercial street development on urban air quality.
Resilience is an emerging concept for analyzing the dynamic performance of critical infrastructures during the post-disaster recovery process. Although a number of studies examined how to assess long-term resilience (1 year +), very few have investigated short-term resilience (few days to several weeks following a disaster). This study presents the new concept of ‘emergency resilience’ and the framework for assessing this short-term resilience for urban lifeline systems in the emergency recovery stage. This framework can quantify differences in system performance (pre-disaster vs. post-recovery) using the new ‘recovery degree’ feature. It also integrates a new performance response function which is based on network equilibrium theory to assess emergency resilience in both the technical and organisational dimensions. In the case study of the water pipeline network in Lianyungang, China, the results showed that the levels of the recovery budget b and recovery resource r had different effects on emergency resilience R in seismic disaster. Furthermore, it is demonstrated how the concept and its assessment framework can provide a quick reference tool for optimal decision-making under various scenarios. This study also examined the effects of two anti-seismic reconstruction measures, namely meshed expansion and ductile retrofitting, on the expected emergency resilience of the water pipeline network.
Reasonable design of the overburden thickness of underground space (OTUS) can influence the outdoor thermal environment by affecting the ground plant communities. To optimize the design of the OTUS for improving the outdoor thermal environment, this study summarized the influence mechanism of the OTUS on the outdoor thermal environment and proposed a framework of the optimization design of underground space overburden thickness. A typical row layout residential area in Nanjing, China, was taken as the research object on which to perform a numerical study of the influence of plant communities formed by two types of plant collocations (a middle- and low-level plant collocation and a middle- and high-level plant collocation) on the outdoor thermal environment (airflow field, air temperature, relative humidity and thermal comfort) under three different ratios of trees to shrubs (2:3, 1:2, and 1:3), and to provide suggestions regarding the design of the OTUS according to the designer’s requirements. The conclusions were summarized as follows: (1) If a designer wants to enhance outdoor ventilation, the OTUS should be designed to satisfy the requirements for the middle- and low-level plant collocations and the overburden thickness of the 2/5 underground space development area should be set to 80~100 cm, the overburden thickness of the other 2/5 area should be set to 45~60 cm and the overburden thickness of the remaining 1/5 area should be set to 30~45 cm. (2) If a designer wants to reduce air temperature, increase relative humidity, and improve outdoor thermal comfort, the OTUS should be designed to satisfy the requirements for middle- and high-level plant collocations and the overburden thickness of the 1/4 underground space development area should be set to 80~100 cm, and the overburden thickness of the remaining 3/4 area should be set to 45~60 cm.
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