Experimental Study on Shield Tunneling Control in Full Section Water-Rich Sand Layer of Collapsible Loess

Mei, Yuan; Zhang, Xinyue; Zhang, Shumin; Wang, Rong; Yang, Tong; Zhang, Yuhang

doi:10.1155/2022/9125283

Cited by 5 publications

(3 citation statements)

References 35 publications

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“…The results indicate that the total pressure distribution on certain tunnel structures gradually increases due to the impact of rainstorms. Mei et al [9] analyzed the impact of shield tunnels crossing water-rich sand layers on land subsidence through experimental studies and proposed a construction control method. Chen et al [10] conducted experiments on tunnels under varying hydrostatic pressures to examine the complex interaction between the seepage field and the stress field in water-rich areas.…”

Section: Introductionmentioning

confidence: 99%

Disturbance characteristics test about double-line shield tunnel excavation in grouting-reinforced water-rich sand stratum

Liu,

Cheng,

Sun

et al. 2024

Eng. Res. Express

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To study the disturbance characteristics of double-line shield tunnel excavation on sand bodies in grouting-reinforced water-rich sand stratum, a similar model test was carried out. Firstly, the physical parameters and strength indexes of the overlying soil strata of the tunnel in the water-rich sand stratum were determined by laboratory tests. The similar soil and tunnel support structures of each stratum were prepared. Then, considering the different seepage modes of upper and lower soil strata under the influence range of tunnel excavation, the model test of double-line shield tunnel excavation in a grouting-reinforced water-rich sand stratum is conducted. The variation rules of sand deformation, surface settlement, and sand body stress during the excavation of a double-line shield tunnel are analyzed utilizing monitoring and analyzing systems such as a flowmeter, micro earth pressure sensors, and dial indicators. It is found that during the excavation of the double-line tunnel, the self-stabilization ability of the grouting reinforced sand bodies is strong under the action of stable seepage. Under the influence of grouting reinforcement, the seepage path around the tunnel structure will change, the fluid-solid coupling effect will decrease, and the sand stratum will be uplifted to varying degrees. The sand body will change its mechanical properties due to the influence of seepage. The fluid-solid interaction effect will be enhanced. The fluid-solid coupling effect of soil particles and water will be further enhanced when the excavation of the subsequent tunnel is carried out. The effect of unsaturated seepage in the overlying soil stratum leads to greater stress at the arch waist of the arch tunnel. In the actual construction process, the grouting amount and grouting time should be strictly controlled. The tunnel basement is supported by anchor spray support to prevent the tunnel structure and surface uplift.

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Section: Introductionmentioning

confidence: 99%

Disturbance characteristics test about double-line shield tunnel excavation in grouting-reinforced water-rich sand stratum

Liu,

Cheng,

Sun

et al. 2024

Eng. Res. Express

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“…So far, there is no precedent for the construction of slotted shields in a loess tunnel. There is no systematic research on the application of a shield method in high-speed railway tunnels, and there is little experience that can be used for reference (Jiang et al, 2017;Yang, et al, 2020;Niu et al, 2021;Weng et al, 2021;Zhu, 2021;Mei et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Study on the construction deformation of a slotted shield in loess tunnels with different buried depths and large sections

Han

Fang

et al. 2023

Front. Earth Sci.

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Since there is no precedent for the use of slotted shield tunneling in the large section of high-speed railways in China, the relevant technological accumulation and systematic research achievements are few. Therefore, this paper provides theoretical support for loess tunnel construction decision-making through the study of slotted shields and is expected to promote the mechanization and even intelligent construction of a high-speed iron-loess tunnel. Taking the Luochuan tunnel of the Xiyan high-speed railway as the engineering background, this paper uses the numerical simulation software packages of ANSYS and FLAC3D to study the tunnel deformation (surface settlement, vault settlement, tunnel bottom uplift, and horizontal convergence) caused by the slotted shield construction in three different buried depths of 30, 40, and 50 m surrounding rock. The deformation law and mechanical characteristics of a cutter shield construction of large cross-section loess tunnels under the influence of different buried depths are put forward. Results showed that 1) the mutual interference between the working procedures can be significantly reduced by inserting the cutting tool into the soil instead of the advanced tubule before excavation; 2) the settlement in the upper part of the longitudinal axis of the tunnel is the largest; the greater the depth of the tunnel is, the smaller the surface settlement is; and 3) the horizontal deformation of the arch waist and foot of the tunnel under different buried depths is symmetrically distributed into the tunnel during the whole process of slotted shield tunneling.

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“…When shields are tunneled through water-rich sandy cobble strata, such as those crossing rivers and springs with richer groundwater, they are more likely to destabilize the excavation surface and cause large ground settlement. Many scholars have drawn attention to the surface settlement caused by shield construction in water-rich sandy cobble strata, but existing studies have mainly adopted the methods of model tests [13][14][15], numerical simulations [16,17] and analytical methods [18], while reliable and practical theoretical prediction methods are lacking.…”

Section: Introductionmentioning

confidence: 99%

Modification of Peck Formula to Predict Surface Settlement of Tunnel Construction in Water-Rich Sandy Cobble Strata and Its Program Implementation

et al. 2022

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There are few studies on the land subsidence induced by shield tunneling in the water-rich sandy gravel stratum, which is of high research value. Linear regression and measured data were employed in this study to investigate the land subsidence induced by shield tunneling when crossing the water-rich sandy gravel stratum from Mudan Dadao Station to Longmen Dadao station of Luoyang Metro Line 2. The maximum land subsidence correction coefficient, α, and the settlement trough width correction coefficient, β, were introduced to modify the peck formula to predict land subsidence induced by shield tunneling in Luoyang’s water-rich sandy gravel stratum. It was discovered that the original Peck formula needs to be modified because its prediction result was significantly larger than the actual value. When the value ranges of α and β in the modified Peck formula were 0.379~0.690 and 0.455~0.508, respectively, the modified Peck formula presented a minor error, in terms of the prediction curve, compared with the original formula, and the prediction result was more reliable. The best prediction result could be obtained when α = 0.535 and β = 0.482. In addition, Python could effectively improve the calculation efficiency of the Peck formula modification.

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Experimental Study on Shield Tunneling Control in Full Section Water-Rich Sand Layer of Collapsible Loess

Cited by 5 publications

References 35 publications

Disturbance characteristics test about double-line shield tunnel excavation in grouting-reinforced water-rich sand stratum

Disturbance characteristics test about double-line shield tunnel excavation in grouting-reinforced water-rich sand stratum

Study on the construction deformation of a slotted shield in loess tunnels with different buried depths and large sections

Modification of Peck Formula to Predict Surface Settlement of Tunnel Construction in Water-Rich Sandy Cobble Strata and Its Program Implementation

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