浅议土的复杂性

李广信

doi:10.11779/CJGE20230188

浅议土的复杂性 English Version

李广信

清华大学水圈科学与水利工程全国重点实验室, 北京 100084

基金项目:

国家自然科学基金项目 52090081

国家自然科学基金项目 52108372

详细信息

作者简介:
李广信(1941—)，男，教授，主要从事土的本构关系、土工合成材料和地基基础等方面的研究工作。E-mail: ligx@tsinghua.edu.cn

中图分类号: TU411
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出版历程
- 收稿日期: 2023-03-02
- 网络出版日期: 2023-07-27
- 刊出日期: 2024-04-30

On complexity of soil

LI Guangxin

State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China

摘要

摘要: 土的复杂性使人很难对其严密地定名与分类，几乎不可能精准地预测其行为。土的复杂性来源于其是天然的产物和碎散的颗粒集合体。土的天然属性使其具有三相组成，土中水成为土力学中理论上的难点，也常常是一切地质灾害与工程事故的根源。土力学教学中所谓的土是被简单化了的，与大自然中的原状土有着很大的差别。土的碎散性使其受力变形性状与物理性质相耦合，在受力变形的过程中其组成、状态、结构都处于不断地变化中，这就是其力学性质非常复杂的主要原因。通过DDA（Discontinuous deformation analysis）分析揭示了土颗粒运动与土的各种变形特性间的联系；土的湿化试验表明了塑性应变是度量土的应力-应变特性的主要因素。人类与土之间有着长期的密切的关系，土作为人类的载体、材料、工具与武器，是人类须臾不可离开的东西。在长期的生活与生产过程中，人们积累了关于土的丰富的经验，也吸取了很多教训。至今经验性的方法仍然是在岩土工程的综合判断与工程决策中的基本方法。
- 复杂性 /
- 自然的产物 /
- 碎散组成 /
- 经验论 /
- 岩土三角形
Abstract: The complexity of soil makes it difficult to name and classify it strictly, and it is almost impossible to predict its behavior accurately. The complexity of soil comes from that it is a natural product and a collection of fragmentary particles. The natural attribute of soil makes it have three-phase composition, and among them, the water in soil causes theoretical difficulties in soil mechanics, and is also the source of almost all geological disasters and engineering accidents. The so-called soil is simplified in soil mechanics teaching, and it is greatly different from the undisturbed soil in nature. In fragmentary soil, its mechanical deformation couples with physical properties, and its composition, state and structure are constantly changing in the process of stress deformation, which is the main reason why its mechanical properties are very complex. The relationship between the movement of soil particles and the various deformation characteristics of soil is revealed through DDA. The wetting tests of soil show that the plastic strain is the main factor to measure the stress-strain characteristics of soil. There is a long and close relationship between the humans and the soil, and as the carrier, material, tool and weapon of mankind, the soil is an indispensable thing for mankind. In the process of long-term life and production, people have accumulated rich experience about soil and learned a lot of lessons. Up to now, the empiricism is still the basic method in the comprehensive judgment and engineering decision-making of geotechnical engineering.
- complexity /
- natural product /
- fragmentary composition /
- empiricism /
- geotechnical triangle

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致谢: 感谢介玉新，朱自立，朱洪在附图方面给予的帮助。

图 1 目标试验中轴向应力应变预测的评分标准

Figure 1. Scoring criteria of stress-strain prediction in target tests

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图 2 含有黏土的粗粒土

Figure 2. Coarse-grained soil with clay

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图 3 原状与重塑的淤泥土

Figure 3. Undisturbed and remolded silt

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图 4 一个土试样的两段试验

Figure 4. Two-stage tests of one sample

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图 5 土颗粒相对位移的几种形式

Figure 5. Several forms of relative displacement of soil particles

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图 6 用DDA分析模型砂应力应变关系

Figure 6. Analysis of stress-strain relationship of model sand with DDA

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图 7 土的受力变形与物性间的耦合

Figure 7. Coupling between mechanical deformation and physical properties of soil

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图 8 干、湿堆石模拟料及其湿化三轴试验

Figure 8. Simulation material of dry and wet rockfill and its wetting triaxial test

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图 9 我国古代的各种加筋土技术

Figure 9. Various reinforced soil technologies in ancient China

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图 10 岩土工程三角形

Figure 10. Geotechnical triangle

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表 1 变形模量与压缩模量间的经验关系

Table 1 Empirical relationship between deformation modulus and constrained modulus

土类	E₀/E_s		土类	E₀/E_s
土类	变化范围	平均值	土类	变化范围	平均值
老黏土	1.45~2.80	2.11	新近沉积黏性土	0.35~1.94	0.93
一般黏性土	0.60~2.80	1.35	新近沉积淤泥质土	1.05~2.97	1.90

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表 2 淤泥质土的强度指标

Table 2 Strength indexes of silty soil

土层	无侧限抗压强度	十字板剪切
土层	q_u/kPa	c_u/kPa
④₁	25.34	28.4
⑥₁	24.06	34.1

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表 3 加载与卸载极限状态的P₁/P₃

Table 3 P₁/P₃ at critical state of loading and unloading

状态	α/(°)	P₁/P₃
状态	α/(°)	加载	卸载
初始—峰值	30	3.732	1.000
峰值强度以后	35	2.748	0.839
残余强度	45	1.732	0.577

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