Predictive model for the surface settlement caused by the excavation of twin tunnels

This paper presents the surface settlement performance induced by the foamed type of earth pressure balance shield in contract CH218 of the Hsintien Line of the Taipei Rapid Transit System. The surface settlement characteristics caused by the single tunnel and by twin tunnels with reference to two sections spaced at 87 m are studied. Field observations indicate that the surface settlement trough due to the single tunnel can be represented by the normal distribution. The distance of the inflection point to the tunnel center and maximum surface settlement value are consistent with those found in the literature. The characteristics of the surface settlement trough are related to the type of the soil, particularly where the crown of the tunnel is located in a layered soil deposit. The ground surface settlement induced by twin tunnels was found to be larger than estimated using the principle of superposition.Key words: shield tunnelling, surface settlement, field observation.

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Modification of Peck Formula to Predict Ground Surface Settlement of Twin Tunnels in Low Permeability Soil

Advances in Civil Engineering ◽

10.1155/2021/6698673 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Xiaowu Tang ◽

Jiaxin Liang ◽

Wei Liu ◽

Yuhang Ye ◽

Penglu Gan ◽

...

Keyword(s):

Ground Surface ◽

Surface Settlement ◽

Low Permeability ◽

Settlement Prediction ◽

Existing Structures ◽

Groundwater Drawdown ◽

Geological Conditions ◽

Modified Formula ◽

Surface Settlement Prediction ◽

Twin Tunnels

Accurate prediction of surface settlement induced by tunnel excavation is significant for preventing damage to existing structures under complex geological conditions. The Peck formula is currently considered as an efficient solution for surface settlement prediction. This paper proposes a modified Peck formula considering geological conditions to improve the accuracy of surface settlement prediction of twin tunnels. The asynchronization of the sinking rate and stability of the vault settlement and surface settlement within the river-affected area may attribute to the groundwater drawdown caused by cofferdam construction on the river. A modified Peck formula is put forward with soil permeability and width-controlling parameters involved. There is a small settlement at the center of the twin tunnels, making the settlement trough upward buckling, which is like a “W” shape. This situation can be accurately predicted by the modified formula with a significantly increased adjusted R-square. The modified formula can accurately predict the surface settlement of tunnels excavated in low permeability soil layers with a permeability coefficient between 10−4 cm/s and 10−7 cm/s, especially in the groundwater drawdown environment. The reliability of the modified Peck formula is verified by other cases in Nanjing and Singapore.

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Investigation of ground surface settlement in twin tunnels driven with EPBM in urban area

Arabian Journal of Geosciences ◽

10.1007/s12517-014-1722-2 ◽

2014 ◽

Vol 8 (9) ◽

pp. 7655-7666 ◽

Cited By ~ 12

Author(s):

Hamid Chakeri ◽

Yilmaz Ozcelik ◽

Bahtiyar Unver

Keyword(s):

Urban Area ◽

Ground Surface ◽

Surface Settlement ◽

Ground Surface Settlement ◽

Twin Tunnels

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3D Numerical Investigation of Ground Settlements Induced by Construction of Istanbul Twin Metro Tunnels with Special Focus on Tunnel Spacing

Periodica Polytechnica Civil Engineering ◽

10.3311/ppci.14591 ◽

2019 ◽

Author(s):

Behnaz Hallaji Dibavar ◽

Mohammad Hossein Ahmadi ◽

Seyed Morteza Davarpanah

Keyword(s):

Urban Areas ◽

Longitudinal Direction ◽

Numerical Approach ◽

Surface Settlement ◽

Special Focus ◽

Direction Parallel ◽

Tunnel Diameter ◽

Twin Tunnels ◽

Good Agreement ◽

Ground Settlements

One of the most important considerations of tunneling in urban areas is controlling the amount of surface settlement that occurs during construction stages. The goal of this paper is to investigate the effect of spacing of Istanbul Twin Metro Tunnels on the surface settlement excavated by NATM method in YENIKAPI-UNKAPANI metro line. For this purpose, the focus has been placed on the effect of longitudinal and transversal spacing between tunnels supported by an umbrella arch protecting method. (FLAC3D) was implemented to simulate the excavation sequence. According to the analysis, the amount of settlement by numerical approach was about 23.5 mm which was in good agreement with the field monitoring results that was 26.5 mm. Moreover, the interaction between twin tunnels by the increase in spacing between twin tunnels in the direction perpendicular to tunnel axis decreases and becomes less effective at the location about 3 times of the tunnel diameter. Similarly, the interaction between twin tunnels in the direction parallel to tunnel axis decreases as the spacing increases. In other words, by increasing the distance between tunnel faces in longitudinal direction at a distance about 3 times of the tunnel diameter, there is still interaction between tunnels and it doesn’t disappear completely. Therefore, it is recommended to keep this distance at about more than 2.5 times of tunnel diameter so that settlement can stay within acceptable range.

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