Disaster mechanism analysis for segments floating of large-diameter shield tunnel construction in the water-rich strata: A case study

Shi, Zhou; Xu, Jinfeng; Xie, Xiongyao; Zeng, Hongbo; Xu, Weijiang; Niu, Gang; Xiao, Zhonglin

doi:10.1016/j.engfailanal.2023.107953

Cited by 6 publications

(2 citation statements)

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“…The overall temperature difference of the brine between delivery and return pipelines also decreases gradually and stabilizes eventually over time. (3) The temperature at each measuring point of the frozen wall decreases linearly with time in the early stage and gradually tends to be stable in the later stage, and the average temperature reaches the designed temperature of −10 • C. It means that good freezing performance can be guaranteed by using insulation and pressurization equipment. The door-like scaffold and pre-stressed ring support can reduce the interplay of excavation of the connection aisle, tunnel excavation, and track laying.…”

Section: Discussionmentioning

confidence: 99%

“…In recent years, with the rapid development of urbanization construction, more and more underground projects are facing the problem of crossing water-rich and weak strata. The reliable treatment method is necessary for these projects; otherwise, it is easy to cause water and sand gushing, pipe gallery deformation, and other engineering accidents, which will bring great difficulty and risk to the engineering construction [1][2][3]. Since artificial ground freezing (AGF) was first used by Sweden to construct a tunnel in 1886, the AGF method was gradually used to construct underground engineering projects [4], which has also been widely used in fields of subways [5], tunnels [6], mining engineering [7], deep excavations [8], drilling [9], etc.…”

Section: Introductionmentioning

confidence: 99%

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Long-Distance Freezing Design and Construction Based on Monitoring Analysis of Subway Connection Aisle

Xu,

Liu,

Zhi

et al. 2024

Coatings

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In the context of a main road area with significant traffic flow, posing challenges to constructing the freezing station on the ground, an innovative proposal suggests situating the freezing station at the station. This approach aims to facilitate construction at the same time for the connection aisle, tunneling, and track laying, thereby reducing the construction period; however, this will lead to a corresponding increase in the freezing pipeline distance. The theoretical analysis, numerical analysis, and integration with engineering practices were employed to examine the essential aspects and key technologies in the long-distance freezing design and construction, including the freezing hole construction, thermal insulation method of brine pipelines and tunnel segments, and technique program to retain the brine pressure and flow discharge, as well as the method to reduce the interplay of cross-construction. The validity of the construction program for the long-distance frozen excavation was finally evaluated based on onsite monitoring and theoretical analysis. The results show that the temperature of the brine in both the delivery and return pipelines first decreases linearly and then stabilizes gradually with freezing time, and the temperature difference is between 1 °C and 1.5 °C at the later freezing period. The temperature variation of the frozen wall is similar to that of brine in the delivery and return pipelines, and there is a good correlation between them. After the frozen wall encloses, the internal pressure of the frozen wall increases quickly, which can be effectively reduced to prevent wall cracking and breakage by regulating the pressure relief holes. The above theoretical analysis result shows that the average temperature of the frozen wall should be less than −9.7 °C when the designed thickness of the frozen wall is 2.2 m. The monitoring data indicates that the average temperature of the frozen wall reaches −13.9 °C, which satisfies the design requirement. The design and construction technology of long-distance freezing enhance the construction of the subway connection aisle. The novel method deviates from the conventional practice of establishing freezing stations within tunnels and offers valuable insight and guidance for comparable projects.

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Section: Discussionmentioning

confidence: 99%