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CLC number: TU472.21

On-line Access: 2020-07-13

Received: 2019-09-16

Revision Accepted: 2019-12-24

Crosschecked: 2020-06-15

Cited: 0

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Citations:  Bibtex RefMan EndNote GB/T7714

 ORCID:

Wei-le Chen

https://orcid.org/0000-0002-4839-6652

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Journal of Zhejiang University SCIENCE A 2020 Vol.21 No.7 P.514-524

http://doi.org/10.1631/jzus.A1900408


Experimental study on the mechanical behavior and deformation characteristics of gravel cushion in an immersed tube tunnel


Author(s):  Wei-le Chen, Chao Guo, Xiao He, Bai-yong Fu, Jian Liu

Affiliation(s):  Shenzhen-Zhongshan Link Administration Center, Zhongshan 528400, China; more

Corresponding email(s):   809487716@qq.com

Key Words:  Immersed tube tunnel, Gravel cushion, Model experiment, Deformation characteristics


Wei-le Chen, Chao Guo, Xiao He, Bai-yong Fu, Jian Liu. Experimental study on the mechanical behavior and deformation characteristics of gravel cushion in an immersed tube tunnel[J]. Journal of Zhejiang University Science A, 2020, 21(7): 514-524.

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volume="21",
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publisher="Zhejiang University Press & Springer",
doi="10.1631/jzus.A1900408"
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%T Experimental study on the mechanical behavior and deformation characteristics of gravel cushion in an immersed tube tunnel
%A Wei-le Chen
%A Chao Guo
%A Xiao He
%A Bai-yong Fu
%A Jian Liu
%J Journal of Zhejiang University SCIENCE A
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%I Zhejiang University Press & Springer
%DOI 10.1631/jzus.A1900408

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T1 - Experimental study on the mechanical behavior and deformation characteristics of gravel cushion in an immersed tube tunnel
A1 - Wei-le Chen
A1 - Chao Guo
A1 - Xiao He
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A1 - Jian Liu
J0 - Journal of Zhejiang University Science A
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SP - 514
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PB - Zhejiang University Press & Springer
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DOI - 10.1631/jzus.A1900408


Abstract: 
The immersed tube tunnel section of the Shenzhen-Zhongshan Link exhibits complex geological conditions and high back sludge strength. The tunnel cushion adopts the gravel and flaky stone combined cushion. The major influencing factors of the mechanical deformation characteristics of the gravel and flaky stone composite cushion are studied through a physical model experiment. The following results are reported. (1) The load–settlement curves of the flaky stone cushion become more compact with a dense increment under the design load. These curves can be regarded as nonlinear mechanical characteristics. The load–settlement curves of the gravel cushion and the gravel and flaky stone composite cushion exhibit the characteristics of a two-stage linear change. (2) The flatness of the top of flaky stone cushion considerably affects settlement and secant modulus. The flatness of the top of flaky stone should be ensured during construction. (3) Gradation and thickness exert no evident effect on the compressibility of a cushion. The preloading pressure caused by the construction height difference of the cushion materials plays an important role in improving the initial stiffness of a cushion and reducing initial settlement and overall settlement. (4) This study investigates the preloading under 30 kPa of the 0.7-m flaky stone and 1.0-m gravel combination cushion. It recommends the following secant modulus values: 48.89 MPa for the section of 0–30 kPa and 10.47 MPa for the section of 30–110 kPa.

沉管隧道碎石垫层力学行为与变形特性试验研究

目的:目前国内外尚无采用二片石+碎石作为沉管隧道先铺法垫层的先例,且二片石+碎石组合垫层的力学变形特性尚不明确. 本文旨在通过室内物理力学模型试验,定量分析二片石及碎石垫层铺设厚度、级配、落管预压荷载量等因素的影响,提出碎石垫层构造方案以及相应的变形模量和承载力等力学指标,以合理确定垫层厚度及可行的施工工艺、准确评估地基刚度偏差、降低淤泥对碎石垫层承载性能的影响以及保证沉管结构的受力安全.
创新点:1. 提出二片石+碎石组合垫层的力学变形特性; 2. 提出落管预压荷载的作用以及对垫层性质的影响.
方法:1. 分别开展二片石和碎石的室内物理力学模型试验,研究二片石与碎石接触面的平整度、颗粒级配、落管预压荷载以及垫层厚度对垫层的物理力学性质的影响,并在此基础上开展二片石+碎石组合垫层的室内模型试验; 2. 提出碎石垫层构造方案以及相应的变形模量和承载力等力学指标,以提高沉管结构的受力安全.
结论:1. 在设计荷载作用下,二片石垫层的荷载-位移曲线呈现越压越密的非线性受力特点,而碎石垫层和碎石+二片石垫层的荷载-位移曲线呈现两阶段线性变化; 2. 二片石垫层顶部的平整密实度对其沉降和压缩模量有很大的影响,因此在施工时需保证二片石垫层顶部的平整密实度; 3. 级配和厚度对垫层的压缩性影响不明显,而落管预压荷载对提高垫层初始刚度以及降低初期沉降和总体沉降有明显作用; 4. 对于预压荷载为30 kPa的0.7 m二片石+1.0 m碎石组合垫层,压缩模量的取值在0~30 kPa段为48.89 MPa,在30~110 kPa段为10.47 MPa.

关键词:沉管隧道; 碎石垫层; 模型试验; 变形特性

Darkslateblue:Affiliate; Royal Blue:Author; Turquoise:Article

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