Abstract
The construction of urban underground cross‐interchange transfer subway stations often encounters the difficulties of shallow‐buried, different surrounding rock, large spans and heights, congested road traffic, and surrounding buildings sensitive to the construction sequence. Therefore, there is a need for an underground project that controls the stability of underground space and ground subsidence. Based on the construction difficulties of a certain station (the maximum excavation area over 760 m2), this paper conducts a comprehensive selection design of the structure, construction mechanics response, and control technology of this type of interchange station structure and construction excavation. First of all, based on the design experience of large‐scale underground transfer transportation engineering and taking full consideration of the stratum conditions, an “arch‐wall” cross transfer structure method is proposed. The refined numerical analysis shows that the structure can fully utilize the stratum conditions to reduce the ground surface settlement. Then, in view of the stability of surrounding rock during the construction of a large section, based on the traditional large section excavation method, a construction method of “cross rock beam + heading method” was proposed. In order to verify the effect of the construction method, the three‐dimensional detailed numerical model was used to simulate the construction conditions, and the mechanical response characteristics and displacement changes of surrounding rock under each excavation step are explored. Simultaneous interpreting with the traditional large section excavation method, the results show that the new method has advantages in controlling the stability of the surrounding rock. Meanwhile, in order to ensure the safe construction of the project, the self‐developed multifunctional engineering test system for traffic tunnels is used to carry out a large‐scale physical model experiment to simulate the entire process of the “arch‐wall” cross transfer structure construction response characteristics. By analyzing the data of measuring points, the results show that the structure form and the excavation method cause the ground surface settlement, stress, and structural forces meet the requirements for safe construction. Finally, the station can be safely constructed under the new structure form and construction method. Therefore, the structure form and method proposed in this paper can be adapted to the large‐scale underground structure under construction in complex environments.
Highlights
Traffic congestion in large cities has become the norm
Transferring ground roads to underground projects is one of the effective ways to resolve the contradiction between the rapid increase in vehicle ownership and the difficult land expansion [1, 2]. erefore, the development of rail transit and urban underground ring roads has become the primary choice for major cities to solve and improve urban transportation, to systematically solve the problem of urban spatial layout and the configuration of transportation network construction, and to fundamentally improve the current urban traffic conditions [3, 4]
We study an underground transfer-station intersection with a large excavation space. e research station is a cross exchange hub for Light Rail Transit Line 3 and Subway Line 6, and it belongs to a shallow-buried underground structure with a large cross section. e ground structures above the station are complex, including Hefu Hotel and Shengtai Automobile City on the east side, North Bus Station on the west side, bus junction station, Ideal Building, and Donghe Yindu Business District. e clearance areas of sections A and B are 580.21 m2 and 383.65 m2, respectively. e traditional crossover design for a large section is a vault crossing (Figure 1(a))
Summary
Traffic congestion in large cities has become the norm. Transferring ground roads to underground projects is one of the effective ways to resolve the contradiction between the rapid increase in vehicle ownership and the difficult land expansion [1, 2]. erefore, the development of rail transit and urban underground ring roads has become the primary choice for major cities to solve and improve urban transportation, to systematically solve the problem of urban spatial layout and the configuration of transportation network construction, and to fundamentally improve the current urban traffic conditions [3, 4]. E mechanical characteristics of the surrounding rock and supporting structure of a tunnel are closely related to its structural characteristics and crossline shape [9, 10] Since this type of underground engineering or rock underground engineering is more sensitive to excavation construction, the overall engineering is complex and the construction is difficult; the main difficulties are as follows: (1) rail transit is generally shallow-buried, and there are complex surrounding environments such as buildings (structures) and municipal pipe networks. With the two vaults at the same elevation, the large excavation span and area can lead to many problems, such as a complex overall tunnel structure, uneven distribution of arch structure stress, surrounding rock during tunnel construction that is prone to landslides, difficulty in underground engineering construction control, and additional engineering project risks. From the above comparative analysis, it can be known that it is reasonable and feasible to choose the “arch-wall” crossover scheme as a large-scale rail transit crossover station structure
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
