Design of the Gongbei tunnel using a very large cross-section pipe-roof and soil freezing method

Jiguo, Liu; Ma, Baosong; Yong, Cheng

doi:10.1016/j.tust.2017.11.012

Cited by 53 publications

(15 citation statements)

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“…Compared with the established subsea tunnel, the S2 tunnel has the following characteristics: (1) the engineering geological and The S2 tunnel is the most critical part of the Gongbei tunnel, which has a service life of more than 100 years. As shown in Figure 2, it traverses under the restricted area of the port with the pipe roof and soil freezing underground excavation method [16], and the cross-section is designed as an egg shape, which is double-deck and symmetrical. Two movement joints are arranged on both sides of the S2 tunnel.…”

Section: Project Overviewmentioning

confidence: 99%

“…(2) It crosses beneath a restricted area of Gongbei Port, which is politically sensitive. In order to ensure normal customs clearance during the construction process, high requirements are placed on environmental protection and deformation control [16]. 3The cross-sectional area of excavation is 344.8 m 2 [18,19], which is about 10 times that of the ordinary subway tunnel.…”

Section: Project Overviewmentioning

confidence: 99%

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Experimental Investigation on Mechanical Characteristics of Waterproof System for Near-Sea Tunnel: A Case Study of the Gongbei Tunnel

et al. 2020

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The water around thenear-sea tunnels is supplied infinitely, and mechanical characteristics of the lining and movement joint are inevitably affected by waterproof methods. The research on the mechanical characteristics of the waterproof system is immature. As a case study of the Gongbei tunnel, a scale model was established in this study, and the stratum, pipe curtain, grouting circle, lining, waterproof board, and movement joint were simulated based on the similarity theories. By changing the externally applied water pressure and drainage discharge, the variation and distribution of the water pressure and strain on the lining with the fully wrapped waterproof (FWW) method, the lining with the partially wrapped waterproof (PWW) method, and the movement joint were investigated. Furthermore, several suggestions on the selection of the waterproof method were presented. The results indicate that the PWW method can reduce the water pressure and strain on the lining under the drained state. Under the state of free drainage, the strain on the lining with the PWW method may get a discount of about 30%. More attention could be paid to the waterproof of the movement joints in the construction process, especially the invert. The research results may offer some valuable insights into the waterproof design of similar near-sea tunnels.

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Section: Project Overviewmentioning

confidence: 99%

Section: Project Overviewmentioning

confidence: 99%

Experimental Investigation on Mechanical Characteristics of Waterproof System for Near-Sea Tunnel: A Case Study of the Gongbei Tunnel

et al. 2020

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“…Based on dimensional analysis [15,16], the temperature field governing equation in the dimensionless form is…”

Section: Similarity Lawsmentioning

confidence: 99%

Evolution Laws for Frozen Wall Formation under Conditions of Sudden Seepage

Zhang

Yue

Sun

et al. 2020

Mathematical Problems in Engineering

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Sudden seepage is a special working condition affecting artificial ground freezing (AGF) in many projects which results in significant differences within the temperature field. In order to study the characteristics of frozen walls influenced by water flow, a series of model tests were carried out at different seepage velocities. The model test results show that a frozen wall will change from symmetrical to eccentric as the cooling energy absorption of the soil and the brine return temperature increase. In model tests, when the seepage velocity was 0∼30 m/d, the frozen wall was partially destroyed. When the seepage velocity exceeded 30 m/d, the frozen wall was completely destroyed. This study examines the expansion rate of the upstream and downstream freezing fronts, and the distribution law of the freezing temperature field, the average temperature change under different seepage speeds, and the bearing capacity of the freezing wall are analyzed. Research on these factors suggests that a frozen wall has a certain level of resistance to sudden seepage. When the flow velocity is small, the freezing effect will be strengthened. With an increase in the flow velocity, the freezing effect will gradually weaken. Based on these conclusions, the current study points out targeted solutions that should be adopted in cases of sudden seepage in a project.

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“…The working conditions when operating at atmospheric pressure operation are better than those of operating under pressure; the former method requires lower technical skills but is more demanding regarding the conditions of the construction stratum. In order to perform normal-pressure operations, the existing technology often adopts the artificial ground-freezing method, which consists of laying multiple cooling pipes which will freeze the surrounding soil, creating a waterproof seal reinforcing the stratum [12][13][14]. However, due to improper operation, cooling pipe frost crack, and other reasons, the waterproof seal may break, and the whole stratum may collapse.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Stress and Temperature Fields in a Composite Stratum Based on a New Method of Shield Construction for Safety and Environmental Protection

Dai

Xia

Ning

et al. 2020

IJERPH

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Safety and environmental protection are key issues in shield construction. Due to wear, the cutter of a shield machine must be changed after a period of excavation. In order to realize the tool change operation of a shield machine at atmospheric pressure, a method of cutter head freezing of the shield machine is described in this paper. The finite element simulation method is used to analyze the construction of a shield machine with a frozen cutter head in a composite stratum. For a composite stratum with uneven hard and soft layers in a ratio of 1:1, the stress and temperature fields are analyzed, and the stress change around the hob is recorded. Through numerical simulation, the change of the temperature field around the shield machine is determined in real time. As time goes on, the temperature around the shield machine decreases, and the frozen range expands. When the temperature field in a specific point reaches a critical value, the temperature at that point will remain constant, and the stress field around the cutter head will also tend to become stable. The isothermal region of the soil presents an annular distribution, and the final temperature tends to be stable and gradually increase as the distance from the frozen cutter head increases. The final temperature of the monitoring area reaches a stable value corresponding to −26.5 °C, the axial depth of the frozen wall is more than 2.5 m, the minimum frozen radius is 3.2 m, the stress distribution around the cutter head is unbalanced, the maximum stress is measured in the hard rock layer, and the stress around the cutter head at the hob level indicates that tool change is necessary. Compared with the traditional method, the construction method of a frozen cutter head is more effective and more environmentally friendly. Further research will allow a broad application of this method in shield excavation in a composite stratum.

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Design of the Gongbei tunnel using a very large cross-section pipe-roof and soil freezing method

Cited by 53 publications

References 1 publication

Experimental Investigation on Mechanical Characteristics of Waterproof System for Near-Sea Tunnel: A Case Study of the Gongbei Tunnel

Experimental Investigation on Mechanical Characteristics of Waterproof System for Near-Sea Tunnel: A Case Study of the Gongbei Tunnel

Evolution Laws for Frozen Wall Formation under Conditions of Sudden Seepage

Numerical Analysis of Stress and Temperature Fields in a Composite Stratum Based on a New Method of Shield Construction for Safety and Environmental Protection

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