循环荷载下海洋软黏土刚度弱化模型研究

周康健; 谢明; 袁志颖

doi:10.20265/j.cnki.issn.1007-2993.2024-0340

循环荷载下海洋软黏土刚度弱化模型研究

doi: 10.20265/j.cnki.issn.1007-2993.2024-0340

周康健^1,,
谢明¹,
袁志颖^{2, 3, ,}

1.
江苏省工程勘测研究院有限责任公司，江苏扬州　225000
2.
浙江工业大学土木工程学院，浙江杭州　310023
3.
江苏鸿基水源科技股份有限公司，江苏扬州　225000

详细信息

作者简介:
周康健，男，1970年生，学士，工程师，主要从事岩土工程勘察工作。E-mail：984568189@qq.com

通讯作者:
袁志颖，男，1997年生，硕士，助理工程师，主要从事岩土工程研究工作。E-mail：1441006648@qq.com

中图分类号: TU411
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出版历程
- 收稿日期: 2024-07-23
- 修回日期: 2024-10-22
- 录用日期: 2025-01-02
- 刊出日期: 2025-10-10

Stiffness degradation model of marine soft clay under cyclic loading

Zhou Kangjian^1
,,
Xie Ming¹,
Yuan Zhiying^{2, 3
, ,}

1.
Jiangsu Province Engineering Investigation and Research Institute Co., Ltd., Yangzhou 225000, Jiangsu, China
2.
College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, Zhejiang, China
3.
Jiangsu Hongji Water Source Technology Co., Ltd., Yangzhou 225000, Jiangsu, China

摘要

摘要: 利用动三轴仪器对舟山原状海洋软黏土进行了一系列不排水条件下的循环三轴试验，分析风浪流等循环荷载作用对正常固结软黏土刚度弱化特性的影响。试验结果表明，土体动模量弱化规律与循环应力比（CSR）密切相关。在未达到临界CSR前，土样双幅轴向应变$ \varepsilon\mathrm{_{DA}} $随着循环次数线性增长；当CSR大于临界CSR后，试样的刚度随循环次数的增加显著退化，致土样破坏。研究发现，不同围压对动模量循环弱化的影响规律可由CSR反映。由试验所得规律建立了土体刚度随循环次数、循环应力幅值和围压变化的经验公式，利用ABAQUS子程序USDFLD实现了海洋软黏土刚度衰减模型在数值模型中的内嵌，研究成果可以为长期循环荷载条件下海上风机基础承载性能的数值模拟研究提供参考。
- 海洋软黏土 /
- 循环荷载 /
- 刚度弱化 /
- ABAQUS子程序
Abstract: A series of cyclic triaxial tests were conducted on Zhoushan undrained marine soft clay with dynamic triaxial instrument to analyze the effects of cyclic loads such as wind and waves on the stiffness degradation characteristics of normally consolidated soft clay. The test results show that the weakening law of soil dynamic modulus closely correlates with CSR. Before the critical cyclic stress ratio CSR is reached, the double-amplitude axial strain $ \varepsilon\mathrm{_{DA}} $ increases linearly with the number of cycles. When the CSR is greater than the critical CSR, the stiffness of the sample degrades significantly with the increase of the number of cycles, so that the soil sample was destroyed. It was found that the influence of different confining pressures on the cyclic weakening of dynamic modulus was effectively captured by CSR. Based on the experimental rules, an empirical formula for soil stiffness variation with the number of cycles, cyclic stress amplitude and confining pressure was established. The stiffness attenuation model of marine soft clay was implemented in the numerical model by using ABAQUS subroutine USDFLD. The research results can provide a reference for the numerical simulation of the bearing performance of offshore wind turbines under long-term cyclic load conditions.
- marine soft clay /
- cyclic loading /
- stiffness degradation /
- ABAQUS subroutine

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图 1 粒径累积曲线

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图 2 GDS动三轴试验系统示意图

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图 3 淤泥质海床土的典型应变特性（CSR = 0.30; p′₀ = 100 kPa）

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图 4 不同CSR下双幅轴向应变的发展

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图 5 试样的典型应力应变关系（CSR = 0.30；p′₀= 100 kPa）

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图 6 在p′₀ = 100 kPa下不同CSR值的轴向动模量的发展

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图 7 不同p′₀值的归一化轴向动模量与循环次数的关系

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图 8 经验参数的确定

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图 9 在p′₀=100 kPa下实测试验数据与预测值的比较

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图 10 在p′₀=50和150 kPa下实测试验数据与预测值的比较

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表 1 常规物理力学特性参数

土样编号	取样深度/m	天然密度ρ/ (g∙cm⁻³)	干密度 ρ_d / (g∙cm⁻³)	土粒比重 G_s	饱和度 S_r /%	孔隙比 e₀	渗透系数k_v / (cm·s⁻¹)
G25-1	0.8～1.0	1.69	1.12	2.71	98	1.42	9.662×10⁻⁶
G47-8	11.8～12.0	1.61	1.02	2.69	95	1.63	8.397×10⁻⁶
G48-1	0.8～1.0	1.71	1.15	2.70	98	1.34	7.840×10⁻⁶

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表 2 不排水循环试验汇总

试验编号	有效固结围压p′₀/kPa	循环偏应力幅值q_cyc/kPa	循环应力比 CSR	循环加载次数N
A1	100	10	0.10	2000
A2	100	15	0.15	2000
A3	100	20	0.20	2000
A4	100	25	0.25	2000
A5	100	30	0.30	2000
A6	100	40	0.40	744
A7	150	30	0.20	2000
A8	150	50	0.33	2000
A9	50	10	0.20	2000
注：p′₀为有效固结围压；q_cyc为正弦波的幅值；N为循环加载次数；$ \mathrm{CSR}=\dfrac{P_0'}{q_{\mathrm{cyc}}} $。

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