复杂应力条件下饱和珊瑚砂各向异性试验研究

马维嘉; 秦悠; 王常德; 陈国兴

doi:10.11779/CJGE202203020

复杂应力条件下饱和珊瑚砂各向异性试验研究 English Version

马维嘉^1,,
秦悠¹,
王常德¹,
陈国兴^{1, 2, ,}

1.
南京工业大学岩土工程研究所, 江苏南京 210009
2.
江苏省土木工程防震技术研究中心, 江苏南京 210009

基金项目:

国家自然科学基金项目 51678299

国家重点研发计划项目 2018YFC1504301

详细信息

作者简介:
马维嘉(1991—)，男，博士研究生，主要从事土动力学研究。E-mail: njtechmwj@163.com

通讯作者:
陈国兴, E-mail: gxc6307@163.com

中图分类号: TU443
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出版历程
- 收稿日期: 2020-12-23
- 网络出版日期: 2022-09-22
- 刊出日期: 2022-02-28

Experimental study on anisotropy of saturated coral sand under complex stress conditions

1.
Institute of Geotechnical Engineering, Nanjing Tech University, Nanjing 210009, China
2.
Civil Engineering and Earthquake Disaster Prevention Center of Jiangsu Province, Nanjing 210009, China

摘要

摘要: 各向异性是珊瑚砂的固有属性。对饱和南沙珊瑚砂开展了一系列不排水单向剪切试验，探究了固结应力方向角α₀和单向加载方向角α_m对饱和珊瑚砂不排水反应的影响。α₀和α_m对饱和珊瑚砂的不排水反应均有显著影响，且α₀与α_m的耦合作用对其不排水反应的影响更为复杂。对所有试验的应力条件，饱和珊瑚砂的超静孔压u_e均呈现出先增大后减小的趋势。α₀不同时饱和珊瑚砂的相变强度S_PT、有效内摩擦角 ${\phi '_{{\text{PT}}}}$ 与α_m的关系存在显著差异。发现饱和珊瑚砂的相变强度S_PT与无量纲参数β存在事实上的线相关性，其中，β是以α₀，α_m为变量的余弦函数。随着广义剪应力q_g的增大，饱和珊瑚砂呈现出明显的应变硬化现象。
- 饱和珊瑚砂 /
- 各向异性 /
- 固结应力方向角 /
- 单向加载方向角 /
- 相变强度
Abstract: Anisotropy is the inherent property of coral sand. A series of undrained monotonic shear tests are carried out on the saturated Nansha coral sand by using the GDS hollow cylinder torsional shear apparatus. The effects of consolidation stress direction angle α₀ and monotonic loading direction angle α_m on the undrained response of saturated coral sand are investigated. The test results show that α₀ and α_m have significant influences on the undrained response of saturated coral sand. The undrained response characteristics of coral sand will become more complex under the coupling effects of α₀ and α_m. For all the test conditions considered, the excess pore water pressure u_e of saturated coral sand presents contraction first and then dilatancy trend. The change of the shear resistance (S_PT) and its effective angle ( ${\phi '_{{\text{PT}}}}$ ) mobilized at the phase transformation state along with α_m are significantly different for various α₀. There is a unique linear correlation between S_PT and the dimensionless parameter β, which is a cosine function with α₀ and α_m as variables. With the increase of the generalized shear stress q_g, obvious strain hardening phenomenon can be observed for the samples.
- saturated coral sand /
- anisotropy /
- consolidation direction angle /
- monotonic direction angle /
- shear resistance at phase transformation point

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图 1 空心圆柱试样受力状态

Figure 1. Hollow cylinder sample under loads

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图 2 空心圆柱扭剪仪（HCA）

Figure 2. Hollow cylinder torsional apparatus

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图 3 珊瑚砂颗粒电镜扫描图像及级配曲线

Figure 3. Scanning electronic microscope graphs and grain-size distribution curve of coral sand

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图 4 固结应力路径

Figure 4. Stress paths of consolidations

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图 5 单向加载应力路径

Figure 5. Stress paths of monotonic loadings

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图 6 不同固结条件下饱和珊瑚砂u_e与γ_g之间的关系

Figure 6. Curves of u_e versus γ_g of saturated coral sand under various consolidation conditions

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图 7 饱和珊瑚砂的有效应力路径

Figure 7. Effective stress paths of saturated coral sand

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饱和珊瑚砂的 ${\varphi '_{{\text{PT}}}}$ 与 ${\alpha _{\text{m}}}$ 的关系

Curves of ${\varphi '_{{\text{PT}}}}$ versus ${\alpha _{\text{m}}}$ of saturated coral sand

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图 9 饱和珊瑚砂S_PT与 ${\alpha _{\text{m}}}$ 的关系

Figure 9. Curves of S_PT versus ${\alpha _{\text{m}}}$ of saturated coral sand

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饱和珊瑚砂 ${\alpha _{\text{0}}}$ 、 ${\alpha _{\text{m}}}$ 与S_PT的关系

Relationship among ${\alpha _{\text{0}}}$ , ${\alpha _{\text{m}}}$ and S_PT of saturated coral sand

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图 11 珊瑚砂S_PT与β的关系

Figure 11. Correlation between S_PT and β of saturated coral sand

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图 12 饱和珊瑚砂q_g与γ_g的关系

Figure 12. Curves of q_g versus γ_g of saturated coral sand

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表 1 试验方案

Table 1 Summary of test schemes

试验编号/No.	固结条件				加载条件		备注
试验编号/No.	${p'_0}$ /kPa	b₀	R_c	α₀/(°)	b_m	α_m/(°)	备注
1	100	—	1	—	0.5	0	均等固结
2						22.5
3						45
4						67.5
5						90
6	100	0.5	1.5	0	0.5	0	各向异性固结
7						22.5
8						45
9						67.5
10						90
11	100	0.5	1.5	45	0.5	0
12						22.5
13						45
14						67.5
15						90
16	100	0.5	1.5	90	0.5	0
17						22.5
18						45
19						67.5
20						90

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