不同固结度下原状软土先动后静强度特性

卢渊; 陈栋格; 陈健; 余颂; 黄珏皓; 付晓东; 马超

doi:10.11779/CJGE2021S2045

不同固结度下原状软土先动后静强度特性 English Version

卢渊^{1, 2,},
陈栋格⁸,
陈健^{1, 2, 3, 4, 5, 6, ,},
余颂⁷,
黄珏皓^{1, 2, 3, 4},
付晓东^{1, 2},
马超¹

1.
中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北　武汉　430071
2.
中国科学院大学,北京　100049
3.
湖北省环境岩土工程重点实验室,湖北　武汉　430071
4.
岩土力学与工程国家重点实验室宁波工程学院工程软土实验中心,浙江　宁波　315211
5.
中国-巴基斯坦地球科学研究中心,伊斯兰堡　巴基斯坦
6.
水下隧道技术国家地方联合工程研究中心,湖北　武汉　430063
7.
中铁大桥勘测设计院集团有限公司,湖北　武汉　430050
8.
云南省滇中引水工程有限公司,云南　昆明　650051

基金项目:

国家自然科学基金面上项目 52079135

国家自然科学基金青年项目 51909259

中国科学院青年创新促进会项目 2021325

详细信息

作者简介:
卢渊(1994— ),男,博士研究生,主要从事软土动静力学特性及随机场在隧道工程的应用研究。E-mail: 462488580@qq.com

通讯作者:
陈健, E-mail: jchen@whrsm.ac.cn

中图分类号: TU43
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出版历程
- 收稿日期: 2021-08-15
- 网络出版日期: 2022-12-05
- 刊出日期: 2021-10-31

Post-cyclic strength behaviors of undisturbed soft soils with different degrees of reconsolidation

LU Yuan^{1, 2,},
CHEN Dong-ge⁸,
CHEN Jian^{1, 2, 3, 4, 5, 6, ,},
YU Song⁷,
HUANG Jue-hao^{1, 2, 3, 4},
FU Xiao-dong^{1, 2},
MA Chao¹

1.
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
2.
University of Chinese Academy of Sciences, Beijing 100049, China
3.
Hubei Key Laboratory of Geo-Environmental Engineering, Wuhan 430071, China
4.
The Soft Soil Research Center in Ningbo University of Technology, State Key Laboratory of Geomechanics and Geotechnical Engineering, Ningbo 315211, China
5.
China-Pakistan Joint Research Center on Earth Sciences, Islamabad, Pakistan
6.
National-Local Joint Engineering Research Center of Underwater Tunneling Technology, Wuhan 430063, China
7.
China Railway Major Bridge Reconnaissance & Design Institute Co., Wuhan 430050, China
8.
Central Yunnan Provincial Water Diversion Project Co., Ltd., Kunming 650051, China

摘要

摘要: 经历动荷载作用后的软土在一段时间后处于完全固结和未固结的中间状态,该状态可用振后固结度的概念进行描述。当前,考虑振后固结度对土体振后强度特性影响的研究较少。因此,通过开展一系列动、静三轴试验,对珠江入海口原状软土的振后强度特性进行研究,重点分析了初始固结围压、循环应力比及振后固结度的影响。试验结果表明：不同条件下土体应力应变曲线的变化趋势相似；土体的振后抗剪强度随着初始围压、循环应力比及振后固结度的增大而增加。其中,当固结围压为20 kPa,振后固结度从0%增加到100%时,抗剪强度从20.2 kPa增加到33.0 kPa；对于振后完全固结的试样而言,当固结围压从20 kPa增加到60 kPa时,对应的抗剪强度从33.0 kPa增加到39.5 kPa。另一方面,存在一临界循环应力比,在该循环应力比作用下,振后土体抗剪强度与相同围压条件下未经历循环荷载作用的土体抗剪强度基本一致。
- 原状软土 /
- 循环荷载 /
- 初始围压 /
- 固结度 /
- 循环应力比 /
- 振后强度特性
Abstract: The soft soil after cyclic loading is often in an intermediate state between unconsolidated and fully reconsolidated after a period of time, which can be described by the concept of degree of reconsolidation. At present, there are few studies considering the effects of different degrees of reconsolidation on the post-cyclic strength behaviors of soils. Therefore, as eries of dynamic and static triaxial tests are carried out to study the post-cyclic strength behaviors of undisturbed soft soils at the Pearl River Estuary. The effects of the initial consolidated confining pressure, cyclic stress ratio and different degrees of reconsolidation on the post-cyclic strength behaviors of soils are analyzed. The test results show that the variation trends of stress-strain curves under different conditions are similar. The post-cyclic shear strength of soils increases with the increase of the initial confining pressure, cyclic stress ratio and degree of reconsolidation. When the confining pressure is 20 kPa and the degree of reconsolidation increases from 0 % to 100 %, the shear strength increases from 20.2 to 33.0 kPa. For the fully reconsolidated specimens after cyclic loading, when the confining pressure increases from 20 to 60 kPa, the corresponding shear strength increases from 33.0 to 39.5 kPa, respectively. On the other hand, there is a critical cyclic stress ratio, at which the post-cyclic shear strength basically equal to that of soils without cyclic loading under the same confining pressure.
- undisturbed soft soil /
- cyclic loading /
- confining pressure /
- degree of reconsolidation /
- cyclic stress ratio /
- post-cyclic strength behavior

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图 1 粒径分布曲线

Figure 1. Grain-size distribution curve

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图 2 不同围压下振后土体的偏应力-应变曲线

Figure 2. Post-cyclic deviator stress-strain curves under different confining pressures

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图 3 不同循环应力比下振后土体的偏应力-应变曲线

Figure 3. Post-cyclic deviator stress-strain curves under different CSRs

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图 4 不同振后固结度下振后土体的偏应力-应变曲线

Figure 4. Post-cyclic deviator stress-strain curves under different degrees of reconsolidation

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表 1 原状软土基本物理力学指标值

Table 1 Indices of basic physical and mechanical properties of undisturbed soft soils

物理力学特性	取值
天然密度ρ/(g·cm^-3)	1.54~1.79
含水率w/%	38.3~69.1
孔隙比e	1.12~1.91
相对质量密度G_s	2.71
液限w_L/%	38.5~61.8
塑限w_P/%	19.4~28.0
塑性指数I_P	19.1~33.8
渗透系数K/(10^-7cm·s^-1)	8.79~10.80
压缩系数a_v/MPa^-1	0.48~1.15
侧压力系数K₀	0.44

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表 2 试验方案

Table 2 Test schemes

试样编号	${p^{'}}_{0}$ /kPa	q^ampl/kPa	CSR	循环次数	U_r/%	S_u/kPa
U₀₁	20	10	0.25	1000	0	20.2
U₀₂	20	10	0.25	1000	25	24.4
U₀₃	20	10	0.25	1000	75	22.8
U₀₄	20	10	0.25	1000	100	33.0
U₀₅	40	20	0.25	1000	100	40.4
U₀₆	60	30	0.25	1000	100	39.5
U₀₇	60	10	0.08	1000	100	32.7
U₀₈	60	20	0.17	1000	100	31.5
U₀₉	60	40	0.33	1000	100	42.9
ST-20	20	—	—	—	—	28.5
ST-40	40	—	—	—	—	33.4
ST-60	60	—	—	—	—	33.5

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参考文献(6)

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