Prediction and analysis of surface settlement due to shield tunneling for Xi’an Metro

Zhu, Caihui; Li, Ning

doi:10.1139/cgj-2016-0166

Cited by 32 publications

(15 citation statements)

References 31 publications

(49 reference statements)

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“…In order to further explore the nine factors (shield support pressure ratio β, grouting filling rate ω, grouting pressure ratio λ, overexcavation rate κ, slope of the shield tunneling machine deviating from the central axis ξ, the ratio of the loosened circle radius η, excess pore pressure ratio ψ, decline in the ratio of the water level θ, and dynamic stress ratio R d ) with respect to their influence degree of the MSS, it is necessary to carry out a single-factor sensitivity analysis. For this study, Xi'an Metro line 2 is taken as the engineering background, and the soil stratum of the tunnel is described as follows: Table 1 [43]. e tunnel axis of Xi'an Metro line 2 is buried 14∼22 m below the ground surface, with an average of H � 19 m, the tunnel excavation diameter is D � 6.2 m, the length of the shield tunneling machine L � 8.68 m, the physical gap of the shield tunneling machine is G p � 160 mm, the control standards for the overexcavation rate are κ � −2.0%∼+2.0%, and the slope of the shield tunneling machine deviating from the central axis is ξ � −3.0%∼+3.0%.…”

Section: Sensitivity Analysis Of the Mss Inducementmentioning

confidence: 99%

Surface Settlement Analysis Induced by Shield Tunneling Construction in the Loess Region

Zhu

2021

Advances in Materials Science and Engineering

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The influence and prediction of shield tunneling construction on surface settlement (SS) and adjacent buildings is a hot topic in underground space engineering. In this work, several analytical methods are utilized to estimate the maximum surface settlement (MSS) and conduct a parametric sensitivity analysis based on Xi’an Metro line 2. The results show that there are mainly nine factors influencing the SS induced by shield tunneling construction in loess strata. The disturbance degree of the surrounding soil during the shield advancing stage has the largest influence on the SS, followed by the seepage of the shield lining segments or falling water levels, which lead to the overlying soil consolidation. After this is the grouting filling effect at the shield tail, followed by the reinforcement effect of the tunnel foundation and the track. The smallest influencing factors on the SS are the shield overexcavation and improper shield attitudes during the construction period. The sensitivity analysis results of the above influencing factors may offer a scientific guidance for the control of shield tunneling construction.

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Section: Sensitivity Analysis Of the Mss Inducementmentioning

confidence: 99%

Surface Settlement Analysis Induced by Shield Tunneling Construction in the Loess Region

Zhu

2021

Advances in Materials Science and Engineering

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“…Advances in Civil Engineering e depth of at the entrance of the Mulingguan tunnel is 5.1 m, the grade of surrounding rock is V grade, the ground loss rate is 0.45% [38], and the friction angle of soil is 30°( Code for Design of Railway Tunnel, China [39]). For the convenience of calculation, the original tunnel section is equivalent to a circular section according to the principle of equal area and buried depth.…”

Section: A Case Studymentioning

confidence: 99%

A New Modified Peck Formula for Predicting the Surface Settlement Based on Stochastic Medium Theory

Song

Tian

Zhang

2019

Advances in Civil Engineering

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Peck method and stochastic medium method are the two most commonly used methods to estimate surface settlement caused by tunnel excavation. However, the Peck method was not suitable for a shallow-buried tunnel, and the calculation process of the stochastic medium theory was complicated. To solve this problem, in this paper, a simple and accurate prediction approach for surface settlement was obtained by improving the Peck method based on the basic idea of stochastic medium theory. In detail, the over-excavation area of the tunnel was divided into n independent units, and the surface settlement caused by the collapse of each unit was calculated, respectively. Then, the total surface settlement can be obtained by superimposing surface settlement induced by each unit. Taking the shallow-buried section of Mulingguan tunnel entrance as a case, the surface settlement calculated by the modified Peck formula and original Peck formula was compared with the observed data, respectively. The comparison results indicated that the surface settlement calculated by the modified Peck formula is closer to the observed data than that calculated by the original Peck formula in the calculation process of surface settlement of shallow-buried tunnel. The table of recommendation for the number of units can be obtained by a discussion of reasonable n values. Finally, the difference between the original Peck formula and the modified Peck formula was analysed, and the results showed that the change rule of the surface settlement is consistent under the tunnel depth, internal friction angle, and ground loss of the tunnel. However, the calculation error of the surface settlements calculated by the original Peck formula is more significant than that calculated by modified Peck formula under the tunnel diameter ratio being less than 1.75. The modified Peck formula is more suitable for calculating the surface settlement under internal angle friction being less than 20° or greater than 40°. The research results expand the scope of application of the original Peck formula and enrich the calculation approach of surface settlement induced by underground excavation in tunnel construction.

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“…where x stands for the distance with the center line of the construction tunnel, S stands for the settlement amount of ground surface which is x away from the center line, max S stands for the maximum settlement amount of ground surface, and i stands for the width coefficient of subsider. The expression of i [10] is:…”

Section: Figure 1: the Schematic Drawing Of Railway Subgrade Settlementmentioning

confidence: 99%

Correlation Between Railway Subgrade Settlement and Shield Tunneling Construction

2019

IJOMAM

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With the rapid development of cities, relevant rail transit construction also develops at a high speed. However, the construction space above the ground is limited, and rail transit covering large construction area is often constructed underground, so the shield tunnel is bound to be used for the underground rail transit construction. In this study, the influence of shield tunneling construction on railway subgrade was analyzed using numerical simulation method, and the influence of stratum reinforcement measures on subgrade in construction process was also analyzed. The results showed that shield tunneling construction could cause subgrade settlement and the influence became larger and larger with the proceeding of project. When the left line was completed, the maximum settlement point was located above the center line of the left tunnel, and the settlement was 7.506 mm. When the right line was completed, the maximum settlement point was located above the central line of the two tunnels, and the settlement was 9.970 mm. Grouting reinforcement measures for stratum around the tunnel could significantly reduce the settlement; the maximum settlement decreased by 62.84% when the left line was completed and 58.65% when the right line was completed. To sum up, shield tunneling construction of railway will cause subgrade settlement, and stratum grouting reinforcement measures can significantly reduce subgrade settlement.

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Prediction and analysis of surface settlement due to shield tunneling for Xi’an Metro

Cited by 32 publications

References 31 publications

Surface Settlement Analysis Induced by Shield Tunneling Construction in the Loess Region

Surface Settlement Analysis Induced by Shield Tunneling Construction in the Loess Region

A New Modified Peck Formula for Predicting the Surface Settlement Based on Stochastic Medium Theory

Correlation Between Railway Subgrade Settlement and Shield Tunneling Construction

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