Reuse of Excavated Clayey Silt in Cement–Fly Ash–Bentonite Hybrid Back-fill Grouting during Shield Tunneling

Xu, Jun; Xiao, Chao; Wu, Huai-Na; Kang, Xin

doi:10.3390/su12031017

Cited by 17 publications

(3 citation statements)

References 43 publications

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“…Waste slurry has been used in other fields, such as ceramic fabrication, according to the different chemical compositions [ 18 , 19 , 20 ]. Meanwhile, in construction engineering, grouting material was created by reusing the slurry (shield tunnels [ 21 , 22 , 23 , 24 ] and waste drilling [ 25 ]).…”

Section: Introductionmentioning

confidence: 99%

Reuse of Drilling Waste Slurry as the Grouting Material for the Real-Time Capsule Grouting Technique

et al. 2023

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A large amount of waste slurry is generated during construction, but direct sedimentation and transportation increase construction costs. Improper treatment leads to ecological and environmental pollution. This paper proposes to reuse drilling waste slurry (DWS) as a raw material from a particular project as a grouting material for the real-time capsule grouting technique (RCG) to replace cement grouting material. This not only deals with DWS but also solves the material demand of RCG. An orthogonal experimental design evaluated the performance of the DWS grouting material (DWS-GM). The five levels for the three factors of this experiment were selected, including the fluidity, bleeding rate, initial setting time, and compression strength. A linear model, support vector machines, and neural networks were used to construct regression models, and the effects of different contents of cement, bentonite, and fly ash on the DWS-GM performance were analyzed. The SVM regression model had better performance in describing the laws of fluidity, bleeding rate, and 28-day compressive strength. Furthermore, the optimization model is proposed to obtain the optimal formulation of the DWS-GM under specific constraints. The optimization results show that the optimal formulation of the DWS-GM was 5.6% cement and 6.9% bentonite. The BL, FL, IST, and 28DCS were 1.61%, 21.87 cm, 27.05 h, and 0.22 MPa to meet the functional requirements of the DWS-GM. The above research fully proves the feasibility of the DWS reuse application. We will further reuse DWS to develop other multifunctional material applications in combination with the control needs of RCG technology and technology from other fields.

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Section: Introductionmentioning

confidence: 99%

Reuse of Drilling Waste Slurry as the Grouting Material for the Real-Time Capsule Grouting Technique

et al. 2023

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“…Currently, urban rail transit systems have served as a favorable means to expedite the modernization of cities [1]. An increasing number of subway tunnels have been developed to alleviate congestion in urban transportation systems [2,3]. Shield-driven tunneling offers the advantages of high efficiency, low cost, and low interference with the surrounding environment, which makes it one of the most advanced and popular tunneling techniques [4].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Underlying Twin Shield Tunnels Due to Foundation-Excavation Unloading in Soft Soils: An Experimental and Numerical Study

Cheng

Hong

et al. 2021

Applied Sciences

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Excavation near or above existing shield tunnels often results in adverse impacts on tunnel stability. To ensure the serviceability of existing tunnels, this paper presents experimental and numerical studies with reference to a foundation pit case history excavated above twin-tube shield tunnels in soft soils. The experimental tests were firstly applied to study the deformation characteristics and structural response of the shield tunnels. Thereafter, an extensive numerical investigation was performed to determine the influence of some factors such as cover-to-excavation depth ratio, length-to-depth ratio, and unloading ratio on tunnel displacement behaviors. It was demonstrated that the tunnel heaves as the excavation proceeds, and heaves and horizontal displacements reach their maximum values when the excavation is finished. The earth pressure around the tunnels is symmetrically distributed in a gourd shape, with a larger reduction at the tunnel crown and invert and a smaller reduction at tunnel side walls. Additionally, the earth pressure at the tunnel crown and invert changes more significantly than that at other parts. The tunnel moment increment is significantly affected by the tunnel excavation depth. The axial force at or near the side walls of the tunnel is the most sensitive to the unloading effect induced by the excavation activity.

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“…It mainly combines catalyst powder and a certain amount of water with extra additives. After fully mixing, the mixed materials are sent to the extrusion machine, selecting different molds according to the need, and then cutting the extrudate into a certain length of product to obtain the catalyst molded product. − Extrusion molding usually includes four steps: raw material conveying, compression, extrusion, and cutting . During the extrusion process, the properties of the mud and the choice of the molding binder have a significant influence on the stability of the extrusion molding catalyst …”

Section: Introductionmentioning

confidence: 99%

Formation of Fly Ash Catalysts and Selection of a Matrix Binder and Its Application in Denitration

et al. 2020

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The development of high-efficiency and low-cost new catalysts is an extremely attractive topic. In this study, two different matrix bentonite-modified fly ash catalysts were successfully prepared, and the compressive strength of the catalyst was studied by using unsaturated dynamic and static triaxial technology. The axial compressive strength of FC (fly ash catalysts added with Ca-based bentonite) was greater than that of FN (fly ash catalysts added with Na-based bentonite). The catalyst reached 978 kPa. The prepared catalyst was characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and specific surface area analysis (BET) of the catalyst. In addition, denitration performance of different catalysts was explored, and the reaction conditions were optimized. The results demonstrate that when the mixing ratio of fly ash and calcium-based bentonite in the FC is 4:1, the compressive strength is relatively high, and the denitration rate reaches about 82%.

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Reuse of Excavated Clayey Silt in Cement–Fly Ash–Bentonite Hybrid Back-fill Grouting during Shield Tunneling

Cited by 17 publications

References 43 publications

Reuse of Drilling Waste Slurry as the Grouting Material for the Real-Time Capsule Grouting Technique

Reuse of Drilling Waste Slurry as the Grouting Material for the Real-Time Capsule Grouting Technique

Characterization of Underlying Twin Shield Tunnels Due to Foundation-Excavation Unloading in Soft Soils: An Experimental and Numerical Study

Formation of Fly Ash Catalysts and Selection of a Matrix Binder and Its Application in Denitration

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