Difficult ground conditions? Use the right chemicals! Chances–limits–requirements

Langmaack, Lars; Lee, Kah Fai

doi:10.1016/j.tust.2016.01.011

Cited by 39 publications

(12 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The conditioning agents used for the EPB shield TBM includ solidification agent (water-absorbing polymer), bentonite, and conditioning agents used in this experiment and their physical pro in Table 2. Foam added to the excavated soil plays roles in inc reducing the internal friction angle, maintaining the uniform dist pressure, and reducing the permeability [15]. In these experiments which is a normal practice in situ [10].…”

Section: Conditioning Agentsmentioning

confidence: 96%

“…The conditioning agents used in this experiment and their physical properties are summarized in Table 2. Foam added to the excavated soil plays roles in increasing compressibility, reducing the internal friction angle, maintaining the uniform distribution of the chamber pressure, and reducing the permeability [15]. In these experiments, an FER of 10 was used, which is a normal practice in situ [10].…”

Section: Conditioning Agentsmentioning

confidence: 99%

See 1 more Smart Citation

Application Ranges of EPB Shield TBM in Weathered Granite Soil: A Laboratory Scale Study

et al. 2021

View full text Add to dashboard Cite

Soil conditioning is a key factor in increasing tunnel face stability and extraction efficiency of excavated soil when excavating tunnels using an earth pressure balance (EPB) shield tunnel boring machine (TBM). Weathered granite soil, which is abundant in the Korean Peninsula (also in Japan, Hong Kong, and Singapore), has different characteristics than sand and clay; it also has particle-crushing characteristics. Conditioning agents were mixed with weathered granite soils of different individual particle-size gradations, and three characteristics (workability, permeability, and compressibility) were evaluated to find an optimal conditioning method. The lower and upper bounds of the water content that are needed for a well-functioning EPB shield TBM were also proposed. Through a trial-and-error experimental analysis, it was confirmed that soil conditioning using foam only was possible when the water content was controlled within the allowable range, that is, between the upper and lower bounds; when water content exceeded the upper bound, soil conditioning with solidification agents was needed along with foam. By taking advantage of the particle-crushing characteristics of the weathered granite soil, it was feasible to adopt the EPB shield TBM even when the soil was extremely coarse and cohesionless by conditioning with polymer slurries along with foam. Finally, the application ranges of EPB shield TBM in weathered granite soil were proposed; the newly proposed ranges are wider and expanded to coarser zones compared with those proposed so far.

show abstract

Section: Conditioning Agentsmentioning

confidence: 96%

Section: Conditioning Agentsmentioning

confidence: 99%

Application Ranges of EPB Shield TBM in Weathered Granite Soil: A Laboratory Scale Study

et al. 2021

View full text Add to dashboard Cite

show abstract

“…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

View full text Add to dashboard Cite

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.

show abstract

“…Many studies on the application of soil conditioning in various given soils have been carried out in recent years. Today, EPBS tunneling is possible through almost all geological conditions, and more and more EPBS machines work in mixed ground due to their large excavation diameter [7] thanks to the application of the soil conditioning system and soil conditioning agents.…”

Section: Introductionmentioning

confidence: 99%

“…Foam agent is a widely used soil conditioner, and bentonite slurry are usually used to modify the grain size distribution of the excavated soils with unfavorable particle composition for EPBS tunneling [12]. For challenging geological conditions, in which the use of water is insufficient, foam and slurry, the structuring and water-binding polymers, are warranted to increase the muck cohesion and decrease permeability, respectively [7]. Foam produced by chemical products, named surfactants or surface-active agents, is usually used in two fields of underground works, including cellular concrete and drilling operations, although the industrial applications of foam are various [13].…”

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

View full text Add to dashboard Cite

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.

show abstract

Difficult ground conditions? Use the right chemicals! Chances–limits–requirements

Cited by 39 publications

References 2 publications

Application Ranges of EPB Shield TBM in Weathered Granite Soil: A Laboratory Scale Study

Application Ranges of EPB Shield TBM in Weathered Granite Soil: A Laboratory Scale Study

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

Contact Info

Product

Resources

About