Performance of a deep excavation in Lanzhou strong permeable sandy gravel strata

Zheng, Yuchao; Xiong, Jun; Liu, Tong; Yue, Xiabing; Qiu, Junling

doi:10.1007/s12517-020-5102-9

Cited by 21 publications

(17 citation statements)

References 60 publications

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“…erefore, the thermal conductivity of ice-containing thermal insulation Note: RSD is the relative standard deviation, which can be used to analyze the accuracy of the results. materials is greater, worsening the effect of thermal insulation materials [46][47][48][49][50][51][52][53].…”

Section: Relationship Between Ermal Conductivity and Gv Of Ice-contaimentioning

confidence: 99%

Thermal Conductivity Characteristics of Thermal Insulation Materials Immersed in Water for Cold‐Region Tunnels

Sun

Zhuang

et al. 2020

Advances in Materials Science and Engineering

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This study investigates the distribution of pore water on the basis of the measured mass moisture content after soaking the tunnel insulation material. This study also analyzes the influence of the distribution of pore water on the thermal conductivity of the material on the basis of this mass moisture content. Scanning images of phenolic and polyurethane insulation boards are obtained by computer tomography (CT). The gray volume moisture content (Gv) is deduced based on the CT scanning images, to determine the distribution of pore water (Gv is the ratio of the volume of the water sample (represented by the gray value) to the volume of the saturated water sample (represented by the gray value) which is the gray volume moisture content of the sample). The correlation between gray volume moisture content and mass moisture content is determined by comparing different algorithms of gray volume moisture content and volume moisture content. The relationship between mass moisture content and thermal conductivity can be determined using a self-made quasi-steady-state tester, whereas the relationship between gray volume moisture content and thermal conductivity can be derived indirectly. Related experimental research can predict the thermal conductivity of thermal insulation materials by using a new perspective and shows the influence of pore water distribution on the thermal conductivity of materials.

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Section: Relationship Between Ermal Conductivity and Gv Of Ice-contaimentioning

confidence: 99%

Thermal Conductivity Characteristics of Thermal Insulation Materials Immersed in Water for Cold‐Region Tunnels

Sun

Zhuang

et al. 2020

Advances in Materials Science and Engineering

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“…e effect of tunneling on existing pile foundations has caused great trouble to the design and construction of urban subway, and many researchers have studied it by numerical and analytical methods [8][9][10][11][12][13][14][15][16]. Besides, a number of centrifuge model tests [17][18][19][20][21][22][23] and field observations [24][25][26][27][28][29][30][31] have been carried out to investigate the influence of tunneling on ground and nearby pile foundations.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study of Protective Schemes for Shield Tunneling Adjacent to Pile Groups

Lai

et al. 2020

Advances in Civil Engineering

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Shield tunneling adjacent to pile groups is always an unavoidable problem in urban metro construction. A case was found in the project of Tianjin Metro Line 7, where a shield tunnel would be constructed near the existing pile groups of Shiyou Bridge. The whole shield tunnel is close to pile groups, and the minimum distance is only 0.8 m. Therefore, four kinds of protective schemes are proposed in this paper. It is vital to select an appropriate protective scheme to guarantee the safety during the tunnel construction. In this study, the main mechanical characteristic and physical parameters of site soil were obtained through laboratory tests. Besides, the three-dimensional finite element method was carried out to compare and analyze the effectiveness of the protective schemes in mitigating the effects of tunneling on adjacent pile groups. The results show that the deep-hole grouting scheme has better control effect on the lateral deformation and bending moment of piles, while the pile foundation underpinning scheme has better effectiveness on reducing the settlement of bridge structure and ground deformation. Finally, the deep-hole grouting reinforcement scheme will be adopted to ensure the shield passing through the pile groups smoothly.

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“…ough multiple forms of grout diffusion occur simultaneously in injected soil, one of them often plays a leading role under certain conditions. For example, materials with large porosity in the sandy layer produce the larger internal pore passages that engender less inhibitory effect during grout flow, which is favorable for effective implementation of the permeation grouting technique [13,14]. In terms of the utilization of the grout materials, the cement slurry now is most commonly used for grouting practices as a result of low cost compared with other grout materials.…”

Section: Introductionmentioning

confidence: 99%

Modelling of Permeation Grouting considering Grout Self-Gravity Effect: Theoretical and Experimental Study

Wang

Zhang

et al. 2019

Advances in Materials Science and Engineering

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Self-gravity is one key parameter for behavior characterization of grout permeation and diffusion.is study proposes mathematical models for permeation grouting with consideration of grout self-gravity effect. e models concerning power law, Bingham, and Newtonian grouts are based on the generalized Darcy's law and spherical diffusion theory. In addition, a prediction model of grout concretion dimension used for Bingham grout was developed. An analysis of the injection pressure distribution law and a comparative evaluation of diffusion radius considering self-gravity effect using established models were conducted subsequently. Moreover, grouting experiments were performed to check and verify the prediction model. e experimental results showed that injection pressure decreases linearly with increase of diffusion radius for the power-law grout, while nonlinear decrease of injection pressure was confirmed in Bingham and Newtonian grouts in this case. ree grouts approximately diffuse in an "ellipsoidal" shape, and it is confirmed that the diffusion radius is closely related to grout self-gravity. e Newtonian grout produces the maximum diffusion radius compared with the other two grouts whether the gravity effects were considered or not. e grout quantity under a smaller water-to-cement (w/c) ratio exhibits a significant difference and undergoes two increasing stages, whereas the quantity simply tends to be stable after it reaches its maximum in terms of the larger (w/c) ratios. e constructed dimension prediction model agrees well with the experimental results, which can be helpful for design and assessment of the grouting scheme.

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Performance of a deep excavation in Lanzhou strong permeable sandy gravel strata

Cited by 21 publications

References 60 publications

Thermal Conductivity Characteristics of Thermal Insulation Materials Immersed in Water for Cold‐Region Tunnels

Thermal Conductivity Characteristics of Thermal Insulation Materials Immersed in Water for Cold‐Region Tunnels

A Comparative Study of Protective Schemes for Shield Tunneling Adjacent to Pile Groups

Modelling of Permeation Grouting considering Grout Self-Gravity Effect: Theoretical and Experimental Study

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