Inheritance and Development of Three Major Engineering Technologies in Xi'an Urban Rail Transit Construction

Objective Cultural relic preservation, collapsible loess foundation treatment, and ground fissure fortification represent the three major engineering challenges in the construction of Xi’an urban rail transit system. Therefore, it is necessary to summarize existing research outcomes and analyze engineering issues that require further consideration.

Method Based on ten more years of experiences in urban rail transit construction and operation, the current state of the three key engineering technologies in Xi’an urban rail transit construction is introduced from cultural relic preservation, collapsible loess foundation treatment, and ground fissure fortification three aspects, key issues for deeper research are analyzed, and future development directions are proposed.

Result & Conclusion  In cultural relic preservation, existing measures systematically address problems of settlement control during construction and vibration control during operation. However, there remains a need to scientifically develop systematic plans for crossing heritage site areas and to further investigate urban rail transit operation vibration-induced damages. In the treatment of collapsible loess foundation, based on large-scale field tests, new collapsibility evaluation methods and foundation treatment approaches are proposed for urban rail transit projects in deep collapsible loess zones. Regarding the foundation in collapsible loess, future work should focus on developing specialized treatment techniques for confined spaces and formulating targeted control measures for under-consolidated saturated loess. In ground fissure fortification, under the general principle of active adaptation, specific measures such as enlarged cross-sections, segmented joints, flexible waterproofing, and adjustable track beds are developed. For fissure-prone areas, systematic technical pathways should be planned with key research on core technologies, including shield tunneling with confined groundwater extraction and the first-shield-then-expansion technology.