基于胞元模型的土体应变局部化试验与机理研究

侯世伟; 侯金招; 杜修力; 孟素云; 曲金红

doi:10.11779/CJGE2024S10012

基于胞元模型的土体应变局部化试验与机理研究 English Version

1.
沈阳建筑大学土木工程学院, 辽宁沈阳 110168
2.
北京工业大学城市与工程安全减灾教育部重点实验室, 北京 100124
3.
中国能源建设集团辽宁电力勘测设计院, 辽宁沈阳 110179

基金项目:

国家自然科学基金项目 52208356

北京工业大学城市与工程安全减灾教育部重点实验室项目 2022B08

详细信息

作者简介:
侯世伟(1982—)，女，博士，副教授，主要从事岩土防灾减灾等方面研究。E-mail: hsw1375@126.com

中图分类号: TU411
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出版历程
- 收稿日期: 2024-04-30
- 刊出日期: 2024-07-31

Strain localization tests of soils and mechanism based on cell model

1.
School of Civil Engineering, Shenyang Jianzhu University, Liaoning 110168, China
2.
The Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, Beijing 100124, China
3.
China Energy Engineering Group Liaoning Electric Power Survey & Design Institute, Shenyang 110179, China

摘要

摘要: 土体的碎散性和天然性使其变形和强度特性具有明显的尺度效应，所以研究土体应变局部化过程，不能忽略级配颗粒的分布和比例关系，须从多个尺度层面表征宏观力学特性。基于胞元模型理论，将土体视作由加强颗粒和基质组成的散体材料，通过三轴压缩试验研究不同加强颗粒粒径试样的内禀尺度规律，并通过数值模拟方法研究了细观层面剪切带的形成过程和启动机理；引入平均应变能释放系数，量化了土体在到达峰值应力之后试样整体的应变能转化情况，再现了多带的启动和渐进竞争过程。结果表明：不同尺度的加强颗粒强度试验说明颗粒的非连续性使土体具有尺寸效应，内禀尺度与粒径之比随加强颗粒尺度增大而减小。在应力峰值前非弹性耗散能增加，引发应变局部化；峰值后，剪切带内应变急速增大，带外发生回弹。
- 尺度效应 /
- 内禀尺度 /
- 剪切带 /
- 三轴压缩试验
Abstract: The fragmentation and naturalness of soils make their deformation and strength characteristics have obvious scale effects. Therefore, in order to study the strain localization process of the soils, the distribution and proportional relationship of graded particles cannot be ignored, and the macroscopic mechanical properties must be characterized from multiple scales. Based on the theory of cell model, the soils are regarded as a granular material composed of reinforced particles and matrix. The intrinsic scale law of the samples with different reinforced particle sizes is studied through the triaxial compression tests, and the formation process and initiation mechanism of shear band at meso level are studied through the numerical simulation. The average strain energy release coefficient is introduced to quantitatively verify the strain energy conversion of the soils after reaching the peak stress, and the multi-band initiation and progressive competition process are reproduced. The results show that the strength tests of reinforced particles with different size scales indicate that the discontinuity of particles makes the soils have size effects, and the ratio of intrinsic scale to particle size decreases with the increase of the reinforced particle size. Before the stress peak, the non-elastic dissipative energy increases, leading to strain localization. After the peak, the strain rapidly increases within the shear band, while there is a rebound outside the band.
- scale effect /
- intrinsic scale /
- shear band /
- triaxial compression test

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图 1 数值模拟与试验竖向应力-竖向应变曲线对比

Figure 1. Comparison of vertical stress-vertical strain curves between numerical simulations and tests

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图 2 试样破坏模式

Figure 2. Damage modes of samples

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图 3 能量与占比曲线

Figure 3. Curves of energy and percentage

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图 4 计算结果与试验结果对比

Figure 4. Comparison between calculated and test results

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表 1 内禀尺度计算及参数

Table 1 Intrinsic scale calculation and parameters

围压/kPa	加强粒径/mm	基体强度/MPa	屈服强度/MPa	内禀尺度/mm	内禀尺度与粒径比
100	0.1~0.2	1.54	4.58	16.81	84.05
	0.4~0.8		2.73	18.36	22.95
	1.0~2.0		2.35	28.45	14.23
	2.0~4.0		2.18	43.08	10.77
	5.0~10		1.88	52.20	5.20
500	0.1~0.2	2.18	6.08	14.52	72.60
	0.4~0.8		4.24	23.84	29.80
	1.0~2.0		3.88	46.42	23.21
	2.0~4.0		3.21	50.36	12.59
	5.0~10		3.21	125.61	12.50
1000	0.1~0.2	2.91	6.81	9.59	6.99
	0.4~0.8		4.82	14.94	18.68
	1.0~2.0		4.78	36.36	18.18
	2.0~4.0		4.72	69.99	17.49
	5.0~10		4.68	170.59	17.10

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