Coupled Effect of Expanded Polystyrene and Geogrid on Load Reduction for High-Filled Cut-and-Cover Tunnels Using the Discrete-Element Method

Li, Sheng; Yao, Yuhang; Ho, I-Hsuan; Wang, Qicai; Wang, Changdan

doi:10.1061/(asce)gm.1943-5622.0001683

Cited by 23 publications

(5 citation statements)

References 29 publications

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“…For HFCCTs, because the earth pressure above a cutand-cover tunnel (CCT) is significant [40], some type of load reduction is needed. Similar load reduction measures, employing geogrid and EPS, geogrid and concrete wedges, and EPS and relatively low-compacted soil, have been shown to be applicable to HFCCTs [41,42].…”

Section: Introductionmentioning

confidence: 89%

Influence of Structural Shape on Earth Pressure for High‐Filled Cut‐and‐Cover Tunnel with and without Load Reduction Based on Discrete Element Method

Zhao

et al. 2020

Advances in Civil Engineering

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In the construction of the Loess Plateau in China, high-filled cut-and-cover tunnels (HFCCTs) had solved the problem of the shortage of land resources. However, this type of structure has a large amount of backfill soil, which leads to the problems of ultrahigh earth pressure and safety of the cut-and-cover tunnels (CCTs) lining structure. Previous studies have focused on the load reduction of various flexible materials, ignoring the influence produced by the shape of the CCT structure on the load reduction. Therefore, via a discrete element software, we investigated the changes of vertical earth pressure (VEP), vertical displacement, lateral earth pressure (LEP), and load transfer mechanisms around a HFCCT with consideration to two cases: (1) different shape of CCT structure; (2) the coupling of load reduction using expanded polystyrene (EPS) and the modified shape of the CCT lining structure. The results obtained by the discrete element method (DEM) revealed that an appropriate structural shape influenced the reduction of the VEP above the CCT and that the coupled effects of the load reduction using the EPS and shape modifications of the CCT lining structure could significantly reduce the VEP above the CCT, which enhanced the safety of the CCT. Meanwhile, the optimal values for the shapes of CCTs are derived.

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Section: Introductionmentioning

confidence: 89%

Influence of Structural Shape on Earth Pressure for High‐Filled Cut‐and‐Cover Tunnel with and without Load Reduction Based on Discrete Element Method

Zhao

et al. 2020

Advances in Civil Engineering

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“…The Linear Contact Bond Model was selected to simulate the contact properties between the soil particles and the wall. In addition, the slopes, foundation, and CCT were simulated by the wall, given that the deformation of the foundation and CCT was much smaller than that of the backfill; that is, the wall that simulated the foundation and the CCT could be regarded as completely rigid (Li et al 2020b). The shear stiffness and normal stiffness of the foundation and CCT were set to 10 10 N/m, which is much greater than the shear stiffness and normal stiffness of the backfill, in the simulation.…”

Section: Materials Parametersmentioning

confidence: 99%

Analysis of Time-Dependent Soil Behavior Above High-Filled Cut-and-Cover Tunnels Using Discrete Element Method

Han

et al. 2022

Geotech Geol Eng

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In the Northwest Loess Plateau of China that is full of mountains and deep valleys, high-filled cut-and-cover tunnels (HFCCTs) not only satisfy transportation demands, but they create usable land as well. Several studies have been conducted to investigate the feasibility of HFCCTs, but the time-dependent behavior of the significant backfill needed for HFCCTs has not been adequately examined. Settlement can be severely underestimated due to the time-dependent behavior of ultra-high backfill, and the earth pressure becomes redistributed accordingly.Therefore, the ability to predict the long-term behavior of backfill on HFCCTs is necessary to ensure the long-term safety of the structure. Using a discrete element method (DEM), the changes in vertical earth pressure (VEP), vertical displacement, and load transfer mechanisms above an HFCCT were investigated in this study under scenarios with and without considering backfill creep.The results show that the differential displacement of the soil and the surface settlement obviously increase due to creep and the subsequent cycles of primary and secondary consolidation. Moreover, the stress surrounding the HFCCT is redistributed, causing both the stress concentration and slope effect to weaken over time, but the VEP increases significantly. The micromechanical parameters also change correspondingly. Our results clearly show that the creep of high backfill soil must be considered carefully in HFCCT projects to ensure structural safety.

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“…The research results determined that the factors have significant effects on the load reduction mechanisms. To optimize the earth pressure reduction on the top of HFCCTs, the influential factors' optimum values were derived [13] .…”

Section: Introductionmentioning

confidence: 99%

Lateral Earth Pressure Reduction on High-Filled Cut-and-Cover Tunnels Using Expanded Polystyrene Geofoam and Tire-Derived Aggregate

Flamarz,

Hajiazizi

2024

PJBAS

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Currently, high-filled cut-and-cover tunnels (HFCCTs) are a practical solution for the prospect of reclaiming valuable usable lands with valleys and hilly terrain around the world. As a result of the very high backfill soil amount above the HFCCT producing very huge earth pressure, it is essential to use methods of load reduction methods to reduce the earth loads and pressures on the HFCCT, which will increase the safety by reducing the tunnel designing loads. This study focuses on six load reduction scenarios using expanded polystyrene (EPS) and tire-derived aggregate (TDA) in three different forms. The research includes using EPS geofoam and TDA in arch and combined horizontal and arch formations as methods of LEP reduction on HFCCTs which is the first time these methods have been used as methods of any type of load reduction on HFCCTs. A number of significant factors, including the suggested EPS and TDA forms, the EPS and TDA thickness, and the distance between the bottom of the EPS or the TDA and the top of the HFCCT were studied. The study results determined that a significant LEP reduction on the HFCCTs was achieved, especially with the use of TDA in a horizontal form. Also, model verification was made by comparison between the calculated and estimated LEP values on the HFCCT study model using the Rankine equation, Rankine modified equation, and Abaqus CAE 2019 software. The calculated and estimated LEP values showed that the calculated value using the Rankine modified equation is 23.61% lower than the calculated value using the Rankine equation, which is a high percentage of difference. The estimated value using Abaqus CAE 2019 is 47.56% higher than the calculated value using the Rankine equation, which is also a high percentage of difference. https://creativecommons.org/licenses/by-nc/4.0/

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Coupled Effect of Expanded Polystyrene and Geogrid on Load Reduction for High-Filled Cut-and-Cover Tunnels Using the Discrete-Element Method

Cited by 23 publications

References 29 publications

Influence of Structural Shape on Earth Pressure for High‐Filled Cut‐and‐Cover Tunnel with and without Load Reduction Based on Discrete Element Method

Influence of Structural Shape on Earth Pressure for High‐Filled Cut‐and‐Cover Tunnel with and without Load Reduction Based on Discrete Element Method

Analysis of Time-Dependent Soil Behavior Above High-Filled Cut-and-Cover Tunnels Using Discrete Element Method

Lateral Earth Pressure Reduction on High-Filled Cut-and-Cover Tunnels Using Expanded Polystyrene Geofoam and Tire-Derived Aggregate

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