Bridge failure is one of the worst infrastructural disasters. This paper investigates the risk of bridge infrastructures in the view of sustainable management. Statistics on bridge failures from 2009 to 2019 in China show that most of these failures are related to anthropic factors. The collapse of the Zijin Bridge on 14 June 2019 in Heyuan City of Guangdong Province, China is used as a case to perform detailed analysis. Superficially, bridge collapse is a technical problem rather than a management problem. However, the deep reason for this kind of bridge failure may be due to the lack of sustainable management. In order to verify this point of view, both fault tree analysis (FTA) and strategic environmental assessment (SEA) for the bridge failure and later impact on society are conducted. According to the FTA results, the failure of the arch foot is the direct trigger of the Zijin Bridge collapse. Since a lack of real-time monitoring, risk assessment and other management issues are potential factors causing bridge collapse, strategic environmental assessment (SEA) is used to investigate the management issues related to the economy, culture, human health and environmental sustainability in more depth. The low total SEA result shows poor project management and a high safety risk. Finally, the specific managerial measures are proposed to improve the sustainability of infrastructures.

During the horizontal jet grouting in soft ground, injection of large volumes of water and grout into the soil can lead to significant ground displacements. A simple method is proposed in this paper to predict the ground displacements caused by installing horizontal jet-grouting columns. The process of installing a horizontal column is simplified as the expansion of a cylindrical cavity with a uniform radial stress applied at plastic-elastic interface in a half plane. In this study, the analytical solution is adopted to calculate the deformation induced by the expansion of a cylindrical cavity. Considering the main jetting parameters (jetting pressure of the fluid, flow rate of the fluid, and withdrawal rate of the rod) and the soil properties (stiffness of the surrounding soil), an empirical equation to estimate the radius of plastic zone is developed. Two field tests are carried out in Shanghai, China, to verify the correctness and applicability of the proposed method. Comparisons between the predicted and measured values indicate that the proposed method can provide a reasonable prediction. The proposed simple method can be recommended as a useful tool for the design of ground improvement by means of horizontal jet grouting.