Manipulations of the sticky clays regarding EPB tunnel driving

Spagnoli, Giovanni; Feinendegen, Martin; Weh, R. Ernst M.

doi:10.1201/b12748-19

Cited by 15 publications

(9 citation statements)

References 0 publications

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“…As shown in the picture above, the foam of agent C has a smaller diameter (<0.2 mm) foam bubble, which accounts for 80% of the total bubble amount. Smaller foam size may result in more stable foam [10]. In addition, the distribution of bubble size amount is fitted with a cubic function in the picture, which indicates that the distribution of agent C's foam bubble size is more concentrated, and the bubble size is more uniform.…”

Section: Microscopic Investigation Of the Bubble Sizementioning

confidence: 92%

“…e optimal range of slump for conditioned soil varies in different researchers [29,[38][39][40]. But a large number of scholars [10,37,40] suggested that the slump value of 10∼15 cm could meet the EPB shield requirement.…”

Section: Slump Testmentioning

confidence: 99%

“…e adaptability of EPB to challenging geological conditions is getting better, in part because of the extensive application of soil conditioning. Soil conditioning, which is achieved by injecting conditioning agents into the soil of the tunnel face and excavation chamber, is used to guarantee effective EPB shield performance and to reduce clogging and cutterhead wearing [8][9][10][11][12][13]. Conditioning agents include foam, polymer, bentonite, and dispersant.…”

Section: Introductionmentioning

confidence: 99%

“…Many researchers use different methods to quantify the adhesion properties of different soils and the improvement of foaming agents. Galli and ewes [1] and ewes et al [10] discussed the methods to determine the quality of foams and soil-foam mixtures and pointed out that the foaming agent type mattered in soil conditioning. Some researchers proposed methodologies [14][15][16] to assess the clogging potential in different situations; in these classification systems, the chart proposed and revised by ewes and Holloman [13,17] is widely accepted.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Methods to Assess the Effectiveness of Soil Conditioning with Foam in Fully Weathered Granite

Tao

Chen

Cui

et al. 2019

Advances in Materials Science and Engineering

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The application range of the earth pressure balance (EPB) shield has been expanded due to advances in optimization methods, one of which is the application of foam conditioning. This method is widely used in EPB tunnelling owing to its strong applicability in different hydrological and geological conditions. When applying the foam conditioning method under different circumstances, it is necessary to optimize the conditioning parameters. Therefore, it is necessary to propose a test procedure for evaluating foam properties and the conditioning effect. This paper proposes a procedure to assess foaming agents by the mixing test and microscopic observation of the foam and a procedure that combines the slump test, compression test, and shear test to assess the foam-conditioned soil and determine the optimal parameters of conditioning. The test method is introduced and performed on fully weathered granite from Guangzhou Metro Line 21. The test results demonstrate that the foam injection ratio and pressure and type of the foaming agent all influence the performance of the conditioned soil. Moreover, the suggested conditioning scheme is proposed, and the application of the scheme can improve the tunnelling efficiency.

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Section: Microscopic Investigation Of the Bubble Sizementioning

confidence: 92%

Section: Slump Testmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental Methods to Assess the Effectiveness of Soil Conditioning with Foam in Fully Weathered Granite

Tao

Chen

Cui

et al. 2019

Advances in Materials Science and Engineering

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“…In these projects, a significant amount of soil conditioned with foam agent was produced. These types of soils exhibit a different behavior from the initial soil thanks to foam's bubbles introduced into the excavated soil [2,9]. Foam used, is commonly defined as a dispersion of gas bubbles in a liquid [10][11][12].…”

Section:  Abstract: Chemical Foam Is Being Used More Frequently Withmentioning

confidence: 99%

Experimental and Modeling of Shear Mechanical Behavior of Soil Conditioned With Foaming Agent

Selmi

Kacem

Jamei

et al. 2019

IJITEE

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Chemical foam is being used more frequently with Earth Pressure Balance (EPB) shields to achieve underground works, which present a rising interest in the excavation technique. During tunneling with an Earth Pressure Balance shield in clayey soil, clogging of the clay occurs, leading to blocking the cutting head and clog then the shield chambers. Surfactants are commonly used as conditioning agents to reduce clay stickiness. This treatment leads to a change in the mechanical properties of conditioned soil. This paper aims tostudy the shear strength behavior of foam-conditioned soil basing on triaxial tests in the undrained consolidated conditions. Experimental results are modeled using the finite element code COMSOL Multiphysics with the aim of analyzing the effect of the percentage of foam on the shear strength behavior. The soil mixture made from 40% of kaolinite and 60% of sand was conditioned with a foaming agent based on anionic surfactant. Consolidated undrained triaxial tests have been performed in order to explain the effect of foam. Results show that foam reduces the shear stress thanks to their weak stiffness. Shear strength stress is affected by the percentage of the foam in the mixture before shearing by reduce the shear strength of the conditioned soil. Soil-foam mixture has been modeled as a medium containing spherical pore inclusions with a low stiffness compared to the stiffness of unconditioned soil. Stiffness of bubbles inclusions was identified using one of the known homogenization models for composite materials. Results show that the reduce shear stress strength is affected by the percentage of inclusions in the matrix. It confirms the friction angle of composite material decrease as function of the percentage of gas bubbles inclusion in the matrix.

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Evaluation of foam application in providing required conditioning for EPB hard rock TBMs

Firouzei

Hassanpour

Peila

et al. 2023

Geomechanics and Tunnelling

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Utilizing the earth pressure balancing technique on hard rock tunnel boring machines (TBMs) is an efficient way to overcome engineering geological hazards that disrupt the application of these machines. Considering that geomechanical and engineering geological conditions of soil and rock are dramatically different, proposing a suitable conditioning design for earth pressure balance (EPB) hard rock TBMs requires particular attention to the characteristics of the excavated material and ground conditions. In this paper, foam application providing a favourable support medium for EPB hard rock TBMs is evaluated based on the experience of the Tehran metro line 6 southern expansion sector project, using laboratory and actual data. TBM muck, with different water contents, was used as the test specimen after granulometry correction. The trend of changes in the workability of foam conditioned mix was obtained by performing 350 slump tests. The pressurized permeability cell test (PPCT), a testing device capable of applying high water pressures to the conditioned material, was used to evaluate the impermeability of workable mixes. Results indicate that although foam can efficiently increase the workability of dry and moistened specimens, the presence of a separated liquid phase in the test specimen disrupts its application; moreover, foam conditioned mix is permeable even against low water pressures.

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Manipulations of the sticky clays regarding EPB tunnel driving

Cited by 15 publications

References 0 publications

Experimental Methods to Assess the Effectiveness of Soil Conditioning with Foam in Fully Weathered Granite

Experimental Methods to Assess the Effectiveness of Soil Conditioning with Foam in Fully Weathered Granite

Experimental and Modeling of Shear Mechanical Behavior of Soil Conditioned With Foaming Agent

Evaluation of foam application in providing required conditioning for EPB hard rock TBMs

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