scholarly journals Numerical prediction of the optimal shield tunneling strategy for tunnel construction in karst regions

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252733
Author(s):  
Zhen Liu ◽  
Weihua Ming ◽  
Jieming Li ◽  
Cuiying Zhou ◽  
Lihai Zhang
Keyword(s):  
Iteration Process ◽  
Karst Region ◽  
Tunnel Construction ◽  
Karst Cave ◽  
Shield Tunneling ◽  
Shield Tunneling Machine ◽  
Karst Areas ◽  
Tunneling Machine ◽  
The Stability ◽  
Shield Machine

Shield tunneling in karst areas poses significant challenges, as vibration caused by the shield machine can disturb the stability of the karst caves, ultimately resulting in the collapse of a tunnel. In the present study, a numerical model involving an iteration process was developed based on the Mindlin solution scheme to identify the optimal shield tunneling speed for minimizing the disturbance to karst cave stability. The developed model was then implemented to investigate an underground tunnel constructed in a karst region with different shield tunneling strategies. By using the variation in the energy density of a karst cave as a performance index, the model predicts that when approaching the affected zone of a karst carve (e.g., approximately 5 m from the carve), the shield tunneling machine should be controlled within a certain speed (i.e., < 30 mm/min). Once the shield tunneling machine moves into the affected zone of the cave, the speed of the machine needs to be decelerated to 11 mm/min, and the speed of 30 mm/min can be restored when the shield machine moves out of the affected zone. This finding demonstrates that the developed model could potentially be used to identify the optimal shield tunneling speed to minimize the disturbance to karst cave stability and ensure the safety of tunnel construction in karst regions.

Impact of Double-O-Tube Shield Tunnel Construction on Grillage Beams Foundation Frame Building

2011 ◽  
Vol 71-78 ◽  
pp. 32-36 ◽  
Author(s):  
Xin Jiang Wei ◽  
Jie Hong ◽  
Gang Wei
Keyword(s):  
Principal Stress ◽  
Differential Settlement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Foundation Settlement ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Frame Building ◽  
Shield Machine ◽  
The Impact

Considering the interaction of building-soil-tunnel, the grillage beams foundation frame building vertical crossed by Double-O-Tube (DOT) shield tunnel was simulated by 3D MIDAS/ GTS software, and the impact of construction on the building was analyzed. The results show that: the ground settlement trough caused by DOT shield tunnel can be fitted by peck formula; during the passage of the shield tunneling through the building, the settlement of the building increased and settlement trough was wilder; the settlement was stable and had a little rebound when shield machine already passed the building; with the increase of driving distance, the first principal stress P1 increased and then was stable; with the increase of L, the shape of foundation settlement curve changed, and the maximum differential settlement between columns increased but was small.

scholarly journals Reuse of Excavated Clayey Silt in Cement–Fly Ash–Bentonite Hybrid Back-fill Grouting during Shield Tunneling

2020 ◽  
Vol 12 (3) ◽  
pp. 1017 ◽  
Author(s):  
Jun Xu ◽  
Chao Xiao ◽  
Huai-Na Wu ◽  
Xin Kang
Keyword(s):  
Fly Ash ◽  
Tunnel Construction ◽  
X Ray Diffraction ◽  
Shield Tunneling ◽  
X Ray ◽  
Mix Proportion ◽  
Clayey Silt ◽  
Before And After ◽  
The Stability ◽  
High Treatment

Excavated soils from tunnel construction need high treatment cost and pollute the environment. To investigate the feasibility of excavated clayey silt reused in back-fill grout, the flowability, stability and strength were taken as measurement indexes of grouting performance. The clayey silt was tested to be reused as substitutes for fly ash, bentonite and sand, respectively. The experimental results indicated that the clayey silt reused as a substitute for fly ash decreased the flowability and strength of grout mixes, and the clayey silt reused as a substitute for bentonite decreased the stability of grout mixes, and neither of them was feasible. The clayey silt reused as a substitute for sand decreased the flowability, but the grouting performance could be improved by adjusting the mix proportion to meet all grouting requirements. After adding the proportion of water to improve the flowability and increasing the cement:fly ash ratio to improve the strength, a scheme of clayey silt reutilization was suggested, which was cement:fly ash:bentonite:clayey silt:water = 280:230:100:680:660. At the end of this paper, the pore structure feature tests, X-ray diffraction (XRD) tests and scanning electron microscope (SEM) tests were performed to analyze the different morphology, microstructure and mineralogy characteristics before and after the clayey silt was reused as a total substitute for sand in grout mixes.

The effects of the pressure outlet's position on the diffusion and pollution of dust in tunnel using a shield tunneling machine

2018 ◽  
Vol 176 ◽  
pp. 232-245 ◽  
Author(s):  
Changqi Liu ◽  
Wen Nie ◽  
Qiu Bao ◽  
Qiang Liu ◽  
Cunhou Wei ◽  
...  
Keyword(s):  
Shield Tunneling ◽  
Shield Tunneling Machine ◽  
Tunneling Machine
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