This project is a research achievement in the field of civil engineering disaster prevention and mitigation. Urban underground pipelines are the lifelines of modern cities, directly related to the safety of urban operations. Over the past twenty years, China has achieved brilliant achievements in the construction of underground pipelines: the total length of large-scale city underground pipelines has increased nearly tenfold, with the total length of urban main pipeline networks reaching 860,000 kilometers. Large-scale expansion, transformation, and new construction have posed unprecedented challenges to the seismic design and safe operation of underground pipelines. In strong earthquakes, underground pipelines are extremely vulnerable to damage. The Wenchuan earthquake in 2008 showed that there were significant hidden dangers to the safety of urban underground pipelines. How to design and construct 'earthquake-proof' underground pipelines is an urgent practical issue that needs to be solved in modern cities. Since 1990, the project team has conducted research on the seismic resistance of urban water and gas supply networks. They have achieved innovative technical results in key technologies for seismic design of large underground networks, including: (1) Establishing seismic calculation formulas for underground pipelines, overcoming the long-term reliance on empirical damage experience in China's pipeline design. Through a large number of seismic performance tests on underground pipelines, they revealed the laws of influence on seismic responses of underground pipelines, and the results have been incorporated into the national new generation engineering seismic standards. (2) Creating the first international seismic function reliability analysis technology system for large urban water supply networks, solving the difficult problem of post-earthquake functional evaluation of large-scale random leakage water supply networks. This has achieved a technological breakthrough in designing 'seismic-resistant' urban water supply networks, and the results are beneficial to the production and reconstruction of cities after earthquakes. Life and disaster relief provided technical support. (3) For the first time, a recursive decomposition theory of structural functions was proposed, establishing large network connectivity reliability recursive decomposition technology, effectively tackling NP-Hard problems in the analysis of large complex networks, solving the difficult problem of seismic connectivity reliability analysis for thousands of node urban underground pipe networks, and achieving breakthrough progress in this field. The recursive decomposition theory has received widespread praise from the international academic community and has been systematically tracked and learned. (4) A seismic topology optimization theory for complex network systems was established, and a large urban underground pipe network seismic optimization design technology was proposed. For the first time internationally, an intelligent design software package for large underground pipe networks was developed and completed, achieving a high degree of unity between safety and economy of the underground pipe network, and an organic combination of seismic design and planning design. After seismic optimization design, the seismic reliability of the pipe network has been significantly improved. The construction cost has been reduced by about 30%. The achievements have been successfully applied in the seismic planning of underground pipe network systems, urban network technology transformation, and new pipeline network seismic design in 26 underground pipe networks in 18 cities, achieving a cumulative economic benefit of 250 million yuan. Among them, the application of water supply pipeline network seismic technology was used in 16 cities including Shanghai, Shenyang, Zhengzhou, etc., and the application of gas supply pipeline network seismic technology was used in 9 cities including Shenyang, Guangzhou, Daqing, etc., providing a successful example for further promotion and application of the project's results. After the Wenchuan earthquake, the achievements were applied in the restoration and reconstruction design of underground pipe networks in major disaster-stricken cities such as Dujiangyan, Mianzhu, Deyang in Sichuan Province, achieving significant social and economic benefits. The project has obtained 5 patents, 2 software copyrights, published 1 monograph, published 74 academic papers, and participated in the compilation of 2 national standards. The achievements have generally established the international leading position of China's large urban underground pipeline seismic design technology, providing important technical support for improving the design level of China's large urban underground pipelines.