Soil Conditioning of Waterless Sand–Pebble Stratum in EPB Tunnel Construction

Zhao, Baoyun; Chen, Lingxin; Jiang, Bin

doi:10.1007/s10706-018-0478-y

Cited by 24 publications

(7 citation statements)

References 10 publications

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“…e particles are in point-to-point contacts and are sensitive to external reactions. Faced with the complexity and uncertainty of engineering geological conditions in this stratum [2,3], the establishment of shield advancement rate prediction models is particularly important in order to ensure safety, control surface settlement, and construction progress. Considerably, shield advancement rate control depends more on manual construction operations [4].…”

Section: Introductionmentioning

confidence: 99%

Research on the Prediction Model of Shield Advancement Rate in Sandy Cobble Ground of Beijing

Li²,

Yang

et al. 2021

Advances in Civil Engineering

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The long distance and tight construction period of the earth pressure balance shield tunneling in Beijing sandy cobble ground have a very positive impact on grasping the construction progress and improving the organization efficiency. Based on the real-time monitoring data of on-site earth pressure, cutter head speed, total thrust, screw conveyor speed, and cutter head torque, this study investigated the correlation between the shield advancement rate and the above parameters based on multiple nonlinear regression analysis method, which lay down the foundation of shield advancement rate prediction. The prediction model achieved satisfactory results and was further applied to an airport project. The results show that it is of guiding significance to use multiple regression method to establish shield prediction model and put forward the best advancement parameters to ensure the construction progress. The order in which the four operational parameters affect the advancement rate is total thrust, cutter head torque, screw conveyor speed, and cutter head speed. When the advancement time is greater than 57 min, the average advancement rate and daily progress are highly positively correlated. The research provides a reliable basis for the advancement rate prediction, safety control, and parameter optimization of shield advancement in similar ground.

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Section: Introductionmentioning

confidence: 99%

Research on the Prediction Model of Shield Advancement Rate in Sandy Cobble Ground of Beijing

Li²,

Yang

et al. 2021

Advances in Civil Engineering

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“…When the groundwater pressure is high, it is not sufficient to rely on foam to improve the impermeability of cohesionless soils. Therefore, it is necessary to add a bentonite slurry or high-molecular-weight polymer materials to improve the impermeability of the cohesionless soils [16,17].…”

Section: Introductionmentioning

confidence: 99%

Effect of Foam Parameters on Cohesionless Soil Permeability and Its Application to Prevent the Water Spewing

Zhou

Yang

2020

Applied Sciences

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Water spewing from the screw conveyor often occurs in cohesionless soil strata below the groundwater level during tunnel excavation with earth pressure balanced (EPB) tunnel boring machines (TBM). Foaming agents have been extensively employed as soil conditioner during the use of EPB TBMs to change the properties of soil, and the conditioned soil, with its low permeability, was the key to reduce the frequency of water spewing. To determine effect of foam parameters on cohesionless soil permeability, the conditioned sand permeability under different foam liquid half-lives ( T hl ) foam expansion rates (FERs), and foam injection rates (FIRs) was tested. To verify the permeability test results, a case study was carried out to optimize the foam parameters for preventing water spewing. Based on these results, this paper suggests that high-stability foaming agents with a medium FER and FIR represent an effective way to reduce cohesionless soil permeability and to prevent water spewing.

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“…Earth pressure balance shield (EPBS) machines, which were originally developed and used in a close mode for fine grained soils or mixed grained soils with at least 30 wt.% fines (d < 0.06 mm) [1,2], have been extensively used in various tunnels because of their high security in driving, high efficiency in tunneling, and high feasibility in stratums. EPBS machines achieve stability of tunnel face by filling the chamber and applying chamber pressure at the back of cutterhead [3], and they have been used in many kinds of excavation soils with complicated characteristics, such as caking property of clayed soils [4], looseness of sandy soils [5], and abrasivity of gravelly soils [6]. Many studies on the application of soil conditioning in various given soils have been carried out in recent years.…”

Section: Introductionmentioning

confidence: 99%

Effects of Soil Conditioning on Characteristics of a Clay-Sand-Gravel Mixed Soil Based on Laboratory Test

Wei

Wang

et al. 2020

Applied Sciences

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Soil conditioning is of great significance for tunneling in soft ground with earth pressure balance shield (EPBS) machines, which leads to safe, highly efficient, and high-quality tunneling. To study the effects of soil conditioning on properties of a clay-sand-gravel mixed soil encountered in an EPBS tunneling project in Beijing, a series of geotechnical test methods was carried out based on laboratory test in this paper. The decay behaviors of foam particles generated by the Waring-Blender method were studied first using the image particle analysis system, and then the feasibility of soil conditioning on the mixed soil was qualitatively and quantitatively assessed through the mixing test, slump test, and friction coefficient test. The preliminary test results indicate that drainage of water in liquid film plays an important role in the decay of foam microstructure. The viscosity and flowability of the conditioned soil were modified dramatically by using various amount of water and foam, and a suitable state meeting the requirement of EPBS machines was obtained. The net power and mixing time, which reflects the interaction between the blending rods and tested soils, as well as the slump value, providing the overall indication for liquidity of the conditioned soils, and friction coefficient, reflecting the friction between steel and tested soils, were used to provide insight into the variation in viscosity and flowability of the tested soils.

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Soil Conditioning of Waterless Sand–Pebble Stratum in EPB Tunnel Construction

Cited by 24 publications

References 10 publications

Research on the Prediction Model of Shield Advancement Rate in Sandy Cobble Ground of Beijing

Research on the Prediction Model of Shield Advancement Rate in Sandy Cobble Ground of Beijing

Effect of Foam Parameters on Cohesionless Soil Permeability and Its Application to Prevent the Water Spewing

Effects of Soil Conditioning on Characteristics of a Clay-Sand-Gravel Mixed Soil Based on Laboratory Test

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