非饱和土的峰值强度特性及破坏包线模型

徐筱; 蔡国庆; 李舰; 赵成刚; 赵春雷

doi:10.11779/CJGE202007004

非饱和土的峰值强度特性及破坏包线模型 English Version

徐筱^{1, 2,},
蔡国庆^2, ,,
李舰²,
赵成刚^{2, 3},
赵春雷⁴

1.
交通运输部公路科学研究院桥梁隧道研究中心,北京　100088
2.
北京交通大学城市地下工程教育部重点实验室,北京　100044
3.
桂林理工大学土木工程学院,广西　桂林　541004
4.
北京城市学院城市建设学部,北京　100086

基金项目:

国家自然科学基金项目 51722802

国家自然科学基金项目 51678041

国家自然科学基金项目 51722802

国家自然科学基金项目 U1834206

北京市自然科学基金项目 8202038

山西省交通运输厅科研项目 2017-1-6

详细信息

作者简介:
徐筱(1991—),男,博士,主要从事非饱和土强度方面的研究工作。E-mail：13115267@bjtu.edu.cn

通讯作者:
蔡国庆, E-mail：guoqing.cai@bjtu.edu.cn

中图分类号: TU43
计量
- 文章访问数: 329
- HTML全文浏览量: 41
- PDF下载量: 234
出版历程
- 收稿日期: 2018-09-29
- 网络出版日期: 2022-12-05
- 刊出日期: 2020-06-30

Peak strength characteristics and failure envelope model of unsaturated soils

XU Xiao^{1, 2,},
CAI Guo-qing^2, ,,
LI Jian²,
ZHAO Chen-gang^{2, 3},
ZHAO Chun-lei⁴

1.
Bridge and Tunnel Research Center, Research Institute of Highway, Ministry of Transport, Beijing 100088, China
2.
Key Laboratory of Urban Underground Engineering of Ministry of Education, Beijing Jiaotong University, Beijing 100044, China
3.
School of Civil Engineering, Guilin University of Technology, Guilin 541004, China
4.
City Construction Department, Beijing City University, Beijing 100086, China

摘要

摘要: 针对非饱和压实土,在不同含水率下,通过三轴压缩试验及抗拉强度试验,研究了非饱和土的峰值破坏点及破坏包线。基于试验结果,讨论了非饱和土破坏包线模型的构成方法。首先,按照土体的破坏模式,破坏包线可表征为两段Mohr–Coulomb型直线。其次,非饱和状态对峰值强度的影响主要表现为剪胀作用和颗粒间作用力两方面,按照非饱和时峰值强度的主要组成部分及其表示方法,给出了黏聚力–剪胀作用型和颗粒间作用力–剪胀作用型两种物理意义明确的曲线型破坏包线。基于分段线性破坏包线,讨论了曲线型破坏包线参数的确定方法。最后,给出并分析了非饱和时不同含水率下土体的破坏包线及其变化特性。
- 非饱和土 /
- 开裂破坏 /
- 剪切破坏 /
- 破坏包线 /
- 剪胀作用 /
- 颗粒间作用力
Abstract: The peak strengths and failure envelopes of unsaturated compacted soils are investigated via triaxial compression and uniaxial tensile tests over a wide range of water content. Based on the experimental evidence, a method for deriving failure envelope model for unsaturated soils is discussed. Firstly, according to the mode of failure, the failure envelope can be approximated by a bilinear Mohr–Coulomb envelope. Secondly, the effect of unsaturated state on the peak strength can be described in terms of dilatancy and interparticle stress. Then accounting for the primary components of unsaturated peak strength and its description, two curved failure envelopes with clear physical meaning are proposed, named after cohesion-dilatancy and interparticle stress-dilatancy envelope respectively. Based on the piecewise linear failure envelope, the method for determining the parameters of the curved failure envelope is discussed. Finally, the failure envelopes and their variation characteristics under different water contents in unsaturated state are given and analyzed.
- unsaturated soil /
- crack failure /
- shear failure /
- failure envelope /
- dilatancy /
- interparticle stress

HTML全文

图 1 河砂的级配曲线

Figure 1. Grain-size distribution curve of sand

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图 2 饱和时的剪切性状

Figure 2. Shear behavior at saturation

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图 3 不同围压下的三轴试验结果（ $w$ =16%）

Figure 3. Results of triaxial tests under different confining pressures ( $w$ =16%)

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图 4 不同含水率下的三轴试验结果（ $σ_{3}$ =50 kPa）

Figure 4. Results of triaxial tests for different water contents ( $σ_{3}$ =50 kPa)

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图 5 不同围压下的应力比–剪胀率关系曲线（ $w$ =16%）

Figure 5. Stress ratio-dilatancy rate curves under different confining pressures ( $w$ =16%)

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图 6 抗拉强度和含水率关系曲线

Figure 6. Tensile strength characteristic curve as a function of water content

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图 7 三轴试样破坏形式

Figure 7. Failure modes of triaxial samples

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图 8 分段线性峰值应力圆包络线（ $w$ =16%）

Figure 8. Piecewise linear envelopes of peak stress circle ( $w$ =16%)

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图 9 曲线型破坏包线（ $w$ =16%）

Figure 9. Curved failure envelopes ( $w$ =16%)

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图 10 不同含水率下的破坏包线

Figure 10. Failure envelopes under different water contents

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表 1 土体的物理特性

Table 1 Physical properties of soils

土的工程分类	相对密度 $G_{s}$	液限 $w_{L} / %$	塑限 $w_{p} / %$	塑性指数 $I_{p}$	最大干密度 $ρ_{d} / (g \cdot {cm}^{- 3})$	最优含水量 $w_{opt} / %$
MHS	2.72	57	38	19	1.3	36

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表 2 破坏包线参数及拟合结果

Table 2 Parameters for failure envelopes and fitting results

含水率/%	线Ⅰ		线Ⅱ			c/kPa(c=c₁)	$σ^{s}$ /kPa	$Δ φ$ /rad ( $Δ φ =$ $φ_{1} - φ_{st}$ )	黏聚力–剪胀作用型		颗粒间作用力–剪胀作用型
含水率/%	c₁/kPa	φ₁/rad	c₂/kPa	φ₂/rad	$R^{2}$	c/kPa(c=c₁)	$σ^{s}$ /kPa	$Δ φ$ /rad ( $Δ φ =$ $φ_{1} - φ_{st}$ )	$P_{N}$ /kPa	$R^{2}$	$P_{N}$ /kPa	$R^{2}$
4	19.66	1.1693	47.95	0.7375	0.9987	19.66	-8.34	0.5553	101.26	0.9998	133.07	0.9995
8	30.80	1.1548	69.16	0.7454	0.9989	30.80	-13.61	0.5408	141.60	0.9999	198.53	0.9991
12	40.14	1.1296	84.59	0.7391	0.9986	40.14	-18.95	0.5156	169.80	0.9998	251.61	0.9984
16	47.16	1.1447	108.90	0.6802	0.9973	47.16	-21.40	0.5307	158.60	0.9990	245.16	0.9968
20	44.11	1.1314	98.37	0.6861	0.9974	44.11	-20.73	0.5174	150.56	0.9992	233.08	0.9969
24	40.93	1.1496	89.69	0.6987	0.9998	40.93	-18.34	0.5356	135.29	0.9999	207.42	0.9986
28	36.31	1.1370	82.24	0.7105	0.9961	36.31	-16.82	0.5230	144.34	0.9986	212.26	0.9968
32	33.71	1.1471	76.44	0.6597	1.0000	33.71	-15.20	0.5331	95.06	0.9999	146.89	0.9985
36	23.47	1.1511	58.93	0.6571	0.9977	23.47	-10.48	0.5371	77.64	0.9992	112.06	0.9978

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