Rethinking the Water Leak Incident of Tunnel LUO09 to Prepare for a Challenging Future

Cheng, Wen-Chieh; Li, Ge; Zhou, Annan; Xu, Jian

doi:10.1155/2019/4695987

Cited by 8 publications

(3 citation statements)

References 42 publications

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“…e construction of urban subways can relieve traffic pressure and improve productivity. Efficiency promotes urban economic development and further accelerates the pace of modernization [1][2][3]. Since 2012, approximately 3 trillion RMB has been invested in China's urban rail transit system, and this number is expected to exceed 500 billion RMB this year.…”

Section: Introductionmentioning

confidence: 99%

Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Niu

Weng

Tian

et al. 2021

Advances in Materials Science and Engineering

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Combined with the soft clay layer of Foshan metro, a back-analysis method combining model test and numerical simulation is developed. First, the similitude criterion for the model used in this study was derived from similarity theory and elasticity mechanics equations. Artificial clay is prepared by mixing kaolin, bentonite, loess, and river sand in proportions of 4 : 2: 3 : 1. Gypsum, water, and borax are mixed in proportions of 1 : 0.7 : 0.015 to simulate the tunnel lining. The model tests were carried out based on four load modes: the combination of mode 1, vertical load distribution and horizontal load linear distribution, mode 2, vertical load distribution and horizontal load parabolic distribution, mode 3, vertical load parabolic distribution and horizontal load linear distribution, and mode 4, vertical and horizontal load parabolic distribution. Then, the calculation model corresponding to the four load modes is established using ABAQUS, and the measured data is back-analyzed as the known quantity. The specific load values obtained were 359 kPa, 380 kPa, 361 kPa, and 368 kPa by the load-internal force curve. The bending moment and axial force are calculated by substituting the back-analysis load values back into the model and comparing the results with the measured values; it was found that the internal forces under the back-calculation load still deviated by varying degrees. By using the comprehensive error function E to evaluate the advantages and disadvantages of the four distribution modes, the comprehensive errors are 4.3%, 1.7%, 6.5%, and 5.9%, respectively. That is, the error of load distribution of mode 2 (the combination of vertical load distribution and horizontal load parabolic distribution) is the lowest and is highly consistent with the measured value, which is the closest to the characteristics of the load pattern of the stratum.

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Section: Introductionmentioning

confidence: 99%

Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Niu

Weng

Tian

et al. 2021

Advances in Materials Science and Engineering

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“…Different construction methods and excavation sequence differences will have an important impact on the tunnel support structure, surrounding rock stress, deformation characteristics, surface settlement, upper existing buildings (structures), and traffic routes [27][28][29][30][31][32]. In the case in which the construction method is determined, determining the optimal excavation sequence is of great significance for reducing the disturbance of the surrounding rock and ensuring the stability of the tunnel structure, upper existing buildings (structures), and traffic safety [33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Construction Sequence Optimization and Settlement Control Countermeasures of Metro Tunnels Underpassing Expressway

Zhang

Pei

et al. 2021

Advances in Civil Engineering

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The Chongqing metro line 6 underpass expressway around the city is taken as an engineering background, and the optimal excavation sequence and corresponding control countermeasures for the triangular-distributed three-line metro tunnel underpass expressway are studied. The influences of excavation sequence on the tunnel surrounding rock deformation, surrounding rock stress, supporting structure stress, plastic zone, and surface settlement are analyzed by using MIDAS/GTS NX finite element software. The numerical simulation results showed that Case 1 is the optimal excavation sequence of the metro tunnel. However, the surface settlement under the optimal excavation sequence exceeds the limit value of 30 mm, which cannot guarantee the safety of expressway traffic. On this basis, the control measure for strengthening the three-line tunnels with advanced small pipe grouting and reinforcing the middle tunnel with concrete-filled steel tube piles are proposed. Moreover, the excavation process of the metro tunnel with and without reinforcement schemes is numerically simulated. The results show that the reinforcement scheme can effectively control the surface settlement value within the limited value (16.47 mm), which is close to the maximum surface settlement of 18.31 mm after the metro tunnel excavation is completed, indicating that the proposed reinforcement scheme is beneficial to ensure the safety of metro tunnel construction and the driving safety of the expressway.

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“…However, owing to a limitation of an urban environment, metro tunnels are usually constructed through a shield method, which achieves a high level of safety. However, when the geological conditions in front of the excavation face are unclear, it will lead to an instability and water gushing of the excavation face [4,5]. At present, there is a lack of case studies and engineering experience on subway tunnels passing through the rock strata in a city.…”

Section: Introductionmentioning

confidence: 99%

Phenomenon and Critical Conditions of Chamber Soil Sliming during EPB Shield Tunneling in Water‐Rich Weathered Diorite: Case Study of Jinan Metro, China

Wang

Qian

et al. 2020

Advances in Civil Engineering

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The sliming problem of chamber soil is caused by excessive groundwater seeping into the pressure chamber when an Earth pressure balance shield tunnels through a water-rich weathered rock stratum under semiopen under-pressure mode. As a solution to this problem, a calculation model was established based on field measurements of the discharged soil properties, the seepage water volume, and the seepage path in Jinan Metro, China. Chamber soil sliming is a phenomenon in which chamber soil is in a thin mud state, with no pressure balance in the pressure chamber of the EPB shield and an excessive water content of the chamber soil owing to the continuous seepage of groundwater into the chamber. The chamber pressure is relatively low, which is different from the phenomenon of spewing when the chamber pressure is relatively high. A large amount of water seepage from the stratum around the tunnel excavation surface and shield to the chamber is a significant factor leading to chamber soil sliming during the construction process. It was considered that when the moisture content of the chamber soil, w, is 2wL ≤ w ≤ 3wL, slight chamber soil sliming may occur, whereas when w ≥ 3wL, serious chamber soil sliming may occur. Moreover, some measures to prevent and control the occurrence of chamber soil sliming were discussed. Controlling the advancing time and the permeability coefficient of chamber soil during construction is the most effective measure to avoid the phenomenon of soil sliming.

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Rethinking the Water Leak Incident of Tunnel LUO09 to Prepare for a Challenging Future

Cited by 8 publications

References 42 publications

Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Construction Sequence Optimization and Settlement Control Countermeasures of Metro Tunnels Underpassing Expressway

Phenomenon and Critical Conditions of Chamber Soil Sliming during EPB Shield Tunneling in Water‐Rich Weathered Diorite: Case Study of Jinan Metro, China

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