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

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Liming Tao ◽  
Zhongtian Chen ◽  
Jian Cui ◽  
Huiwu Wang ◽  
Yong Fang
Keyword(s):  
Test Procedure ◽  
Earth Pressure ◽  
Optimization Methods ◽  
Test Method ◽  
Pressure Balance ◽  
Foaming Agents ◽  
Application Range ◽  
Weathered Granite ◽  
Geological Conditions ◽  
Foam Properties

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.

Study on Soil Conditioning and Key Construction Parameters of EPB TBM Advancing in Sand-Pebble Layer of Beijing Metro

2011 ◽  
Vol 90-93 ◽  
pp. 2138-2142 ◽  
Author(s):  
Hua Jiang ◽  
Yu Sheng Jiang ◽  
Mao Lan Huang ◽  
Xin Nie
Keyword(s):  
Plastic Flow ◽  
Earth Pressure ◽  
Soil Condition ◽  
Pressure Balance ◽  
Soil Conditioning ◽  
Geological Conditions ◽  
Before And After ◽  
Epb Tbm ◽  
Earth Pressure Balance ◽  
Low Efficiency

Mechanical properties of sand-pebble layer is very unstable, it is unfavourable for TBM excavation. For the reasons of poor soil conditioning and low plastic flow of muck, EPB TBM tunnel construction in sand-pebble layer of Beijing metro has exposed variety of issues: continuous dynamic earth pressure balance is hard to established, mud cake is formed frequently in earth chamber, key construction parameters such as thrust, torque, advance speed can not be controlled in reasonable scopes, which lead to low efficiency of TBM construction. Taking“Xi-Liu”of line 10 lot 11 as an research object, the mechanical characteristics of sand-pebble layer and construction problems of TBM advancing are analyzed, variety of soil conditioning measures are used for improving plastic flow of muck and minimizing construction influence induced by poor geological conditions, meanwhile contrast studies on key construction parameters before and after soil conditioning are carried out. The results indicate that effect of soil condition plays very significant roles in controlling TBM construction parameters and improving advancing efficiency.

Theoretical Research and Improvement of Cutter Head for Earth Pressure Balance Shield Pipe-Jacking Machine

2015 ◽  
Vol 757 ◽  
pp. 115-119
Author(s):  
Man Long Chen ◽  
Wen Dong Chen
Keyword(s):  
Earth Pressure ◽  
Theoretical Research ◽  
Tool Geometry ◽  
Pressure Balance ◽  
Shape Transformation ◽  
Geological Conditions ◽  
Earth Pressure Balance Shield ◽  
Tool Shape ◽  
Pipe Jacking ◽  
Earth Pressure Balance

In this paper, the pipeline project construction site, for example, analyze the different geological conditions in the Northwest Earth pressure balance pipe jacking machine cutter wear serious reasons put forward reasonable arrangement cutter tool, tool shape transformation plan, proposed by the tool layout and tool geometry and other technical measures through on-site construction work to prove that the cutter tool life under continuous construction conditions improved.

scholarly journals Mesocosm Experiments at a Tunnelling Construction Site for Assessing Re-Use of Spoil Material as a By-Product

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 161
Author(s):  
Anna Barra Caracciolo ◽  
Paola Grenni ◽  
Livia Mariani ◽  
Jasmin Rauseo ◽  
Martina Di Lenola ◽  
...  
Keyword(s):  
Water Extract ◽  
Earth Pressure ◽  
Construction Site ◽  
Pressure Balance ◽  
Foaming Agents ◽  
Main Compound ◽  
Final Destination ◽  
Soil Mesocosms ◽  
Earth Pressure Balance ◽  
Boring Machines

Mechanized excavation of tunnels with Earth Pressure Balance-Tunnel Boring Machines requires the use of foaming agents. The latter contain the anionic surfactant sodium lauryl ether sulphate (SLES) as the main compound. The re-use as a by-product of excavated soil containing foaming agents (spoil material) can pose a risk for soil and particularly for aquatic ecosystems if they are close to the spoil material final destination site. This work reports the chemical results (SLES residual concentrations) and ecotoxicological effects (battery of five tests) of 28 day-mesocosm studies performed at a tunnelling construction site. The soil mesocosms were set up with two different lithologies, which contained four different foaming agent products at the highest amounts used for excavation. The decrease in SLES concentrations and the ecotoxicological tests were performed in soil and its water extract (elutriate) at different times (0, 7, 14, 28 d). Elutriates were prepared in order to simulate a possible SLES leaching from soil to water. The results showed a decrease in SLES over time and different ecotoxicological responses depending not only on the initial amount of each product, but also on the soil lithology and organism tested (aquatic or terrestrial). This study showed how only site-specific ecotoxicological evaluations can ensure a safe management of the spoil material, making possible the re-use of soil and avoiding production of waste.

Properties Test and Application on New Synchronous Grouting for the Earth Pressure Balance Shield

2011 ◽  
Vol 233-235 ◽  
pp. 101-104
Author(s):  
Guo Gang Qiao ◽  
Da Jun Yuan
Keyword(s):  
Earth Pressure ◽  
Test Method ◽  
Raw Material ◽  
Pressure Balance ◽  
Performance Requirements ◽  
Injection Pump ◽  
Earth Pressure Balance Shield ◽  
Surface Subsidence Control ◽  
Earth Pressure Balance ◽  
And Performance

The type and performance indicators of the grout contribute great impact on the grouting effect. Uniform test method was adopted on the mix design optimization of the new grout, and the raw material requirements and performance requirements of the new grout were developed. Test results of the new grout, inert grout, and cement grout performances were compared and conclusions were drawn that the overall performances of the new grout were better than the other two type grouts. The modification of injection pump and pipe for the new grout injection were introduced, the preliminary application results of Shanghai and Suzhou metro showed that the new grout played a very good role on the surface subsidence control.

scholarly journals Bioaugmentation With a Consortium of Bacterial Sodium Lauryl Ether Sulfate-Degraders for Remediation of Contaminated Soils

2021 ◽  
Vol 12 ◽  
Author(s):  
Ludovica Rolando ◽  
Anna Barra Caracciolo ◽  
Paola Grenni ◽  
Livia Mariani ◽  
Jasmin Rauseo ◽  
...  
Keyword(s):  
Contaminated Soils ◽  
Earth Pressure ◽  
Bacterial Consortium ◽  
Pressure Balance ◽  
Soil Extracts ◽  
Foaming Agents ◽  
Sodium Lauryl Ether Sulfate ◽  
Ether Sulfate ◽  
Lauryl Ether ◽  
Boring Machines

The anionic surfactant sodium lauryl ether sulfate (SLES) is the main component of most commercial foaming agents (FAs) used in the excavation of highway and railway tunnels with Earth pressure balance-tunnel boring machines (EPB-TBMs). Several hundreds of millions of tons of spoil material, consisting of soil mixed with FAs, are produced worldwide, raising the issue of their handling and safe disposal. Reducing waste production and reusing by-products are the primary objectives of the “circular economy,” and in this context, the biodegradation of SLES becomes a key question in reclaiming excavated soils, especially at construction sites where SLES degradation on the spot is not possible because of lack of space for temporary spoil material storage. The aim of the present work was to apply a bacterial consortium (BC) of SLES degraders to spoil material excavated with an EPB-TBM and coming from a real construction site. For this purpose, the BC capability to accelerate SLES degradation was tested. Preliminary BC growth, degradation tests, and ecotoxicological evaluations were performed on a selected FA. Subsequently, a bioaugmentation experiment was conducted; and the microbial abundance, viability, and SLES concentrations in spoil material were evaluated over the experimental time (0.5, 3, 6, 24, 48, and 144 h). Moreover, the corresponding aqueous elutriates were extracted from all the soil samples and analyzed for SLES concentration and ecotoxicological evaluations with the bacterium Aliivibrio fischeri. The preliminary experiments showed the BC capability to grow under 14 different concentrations of the FA. The maximum BC growth rates and degradation efficiency (100%) were achieved with initial SLES concentrations of 125, 250, and 500 mg/L. The subsequent bioaugmentation of the spoil material with BC significantly (sixfold) improved the degradation time of SLES (DT50 1 day) compared with natural attenuation (DT50 6 days). In line with this result, neither SLES residues nor toxicity was recorded in the soil extracts showing the spoil material as a by-product promptly usable. The bioaugmentation with BC can be a very useful for cleaning spoil material produced in underground construction where its temporary storage (for SLES natural biodegradation) is not possible.

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

2021 ◽  
Vol 11 (7) ◽  
pp. 2995
Author(s):  
Tae-Hwan Kim ◽  
In-Mo Lee ◽  
Hee-Young Chung ◽  
Jeong-Jun Park ◽  
Young-Moo Ryu
Keyword(s):  
Water Content ◽  
Upper And Lower Bounds ◽  
Shield Tunnel ◽  
Particle Crushing ◽  
Pressure Balance ◽  
Soil Conditioning ◽  
Weathered Granite ◽  
Weathered Granite Soil ◽  
Granite Soil ◽  
Epb Shield

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.

scholarly journals Analysis of the influence of asymmetric geological conditions on stability of high arch dam

2021 ◽  
Vol 28 (1) ◽  
pp. 426-436
Author(s):  
Zelin Ding ◽  
Xuanyi Zhu ◽  
Hongyang Zhang ◽  
Hanlin Ban ◽  
Yuan Chen
Keyword(s):  
Safety Factor ◽  
Negative Impact ◽  
Decisive Role ◽  
Arch Dam ◽  
Test Method ◽  
Stable Operation ◽  
High Arch Dam ◽  
Reinforcement Scheme ◽  
Structural Plane ◽  
Geological Conditions

Abstract Geological conditions play a decisive role in the stability of arch dam engineering, and the asymmetric geological conditions of the abutment have a very negative impact on the safety of the arch dam. This article takes Lizhou arch dam as the research object, and determines that the arch dam is preliminarily affected by the geological asymmetric characteristics. Through the geomechanical model test method, the overload failure test of the Lizhou arch dam was carried out, and the resistance body, the instability deformation of the structural plane of the two dam abutments, and the influence of each structural plane on the dam body are obtained, and the safety factor is determined. According to the test results under the condition of asymmetric foundation of arch dam, for the structural plane which affects the geological asymmetry of the arch dam, the corresponding reinforcement measures are carried out. The feasibility of the reinforcement scheme is verified by the finite element method, and the safety factor after reinforcement is obtained. According to the results, it is suggested that some engineering measures can be taken to reduce the geological asymmetry between the two banks and ensure the safe and stable operation of the arch dam in the future.

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