冻土地基中锥管板条装配式基础抗拔承载性能试验研究

张学礼; 崔强; 张树林

doi:10.19509/j.cnki.dzkq.2022.0050

冻土地基中锥管板条装配式基础抗拔承载性能试验研究

doi: 10.19509/j.cnki.dzkq.2022.0050

张学礼^1,,
崔强^2, ,,
张树林³

基金项目:

国家电网公司科技项目"特高压直流工程换流站与线路基础的装配式模块关键技术研究" GCB17201700134

详细信息

作者简介:
张学礼(1982-), 男, 高级工程师, 主要从事电力线路工程设计工作。E-mail: zhangxueli310@163.com

通讯作者:
崔强(1980-), 男, 正高级工程师, 主要从事输变电工程试验检测及科研工作。E-mail: everjsl@126.com

中图分类号: TU432
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- 文章访问数: 308
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- 被引次数: 0
出版历程
- 收稿日期: 2021-02-05

Experimental research on uplift bearing capacity of the assembled foundation with cone tube and slab in frozen subsoil

摘要

摘要: 为了分析冻土地基中输电线路基础发生冻拔破坏的科学问题, 以锥管板条装配式基础为研究对象, 采用室内模型试验测试及分析的研究方法, 开展了不同环境温度下, 冻土地基的冻结试验和基础的上拔加载试验, 分析了地基温度场、位移场的分布特征以及基础抗拔承载力与温度之间的关系, 揭示出上拔荷载作用下冻土地基的破坏模式。研究结果表明: 冻结试验中, 模型基础的冻拔位移均小于周围地基土体的冻胀位移, 基础对地基土体的冻胀存在反约束作用, 距离基础越近, 约束作用越明显; 不同冻结环境温度下基础的上拔加载试验中, 抗拔极限承载力均随环境温度的降低近似呈线性增大, 增加速率接近1.8 kN/℃; 在冻结与上拔力双重作用下, 地基土体首先出现局部张拉破坏, 随着上拔荷载的不断增加, 地基土体逐渐由局部张拉破坏过渡为整体剪切破坏。研究成果可为这种形式的基础在冻土地基中的应用提供理论依据和实践经验。
- 冻土地基 /
- 锥管板条装配式基础 /
- 模型试验 /
- 冻胀量 /
- 荷载-位移曲线 /
- 抗拔承载性能
Abstract: Aiming at the scientific problem of transmission line foundation freeze-thaw failure in frozen subsoil, this paper takes an assembled foundation with cone tubes and slabs as the research object. The research method of the indoor model test and analysis is adopted, and a series of freezing tests and uplift loading tests of the model foundation are carried out under different ambient temperatures. The distribution characteristics of the temperature field and displacement field of the foundation and the relationship between the ultimate uplift capacity and temperature are analysed. Simultaneously, the failure mode of the frozen soil foundation under uplift load is also revealed. The research results show that in the freezing test, the displacement of the model foundation is less than the frost heave displacement of the surrounding foundation soil; the closer the distance from the foundation is, the stronger the frost heaving anti-restraint effect of the foundation is.In the uplift loading test of the foundation under different freezing ambient temperatures, the ultimate uplift capacity increases approximately linearly with the decrease in the ambient temperature, and the increase rate is close to 1.8 kN/℃. Under the double action of freezing and uplift, the foundation soil first exhibits local tensile failure, and with the increasing uplift load, the foundation soil gradually transitions from local tensile failure to overall shear failure. The results of this paper can provide a theoretical basis and practical experience for the application of this type of foundation in frozen subsoil.
- frozen subsoil /
- assembled foundation with cone tube and slab /
- model test /
- frost heaving /
- uplift load-displacement curve /
- ultimate uplift capacity

HTML全文

图 1 锥管板条装配式基础示意图

Figure 1. Schematic diagram of the assembled foundation with a cone tube and slab

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图 2 取样现场

Figure 2. Sampling site

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图 3 试验装置

Figure 3. Test device

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图 4 位移传感器布置示意图(数值单位: mm)

Figure 4. Schematic diagram of the displacement sensor layout

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图 5 温度传感器布置示意图(数值单位: mm)

Figure 5. Schematic diagram of the temperature sensor layout

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图 6 环境温度随时间变化曲线(图 5中T0传感器)

Figure 6. Change curve of ambient temperature with test time

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图 7 不同位置处地基温度随时间变化曲线(-10℃)

Figure 7. Change curve of soil surface temperature with time at different positions(-10℃)

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图 8 基础顶部与地基表面处上拔位移随时间的变化曲线

Figure 8. Change curve of foundation top and soil surface uplift displacements with test time

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图 9 地基上拔位移与距基础边缘距离之间的关系曲线

Figure 9. Relation curve between freeze-drawing displacement and distance from foundation edge

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图 10 地基基础表面最终冻胀量随温度变化曲线

Figure 10. Change curve of the final freeze-drawing of the foundation and soil surface with temperature

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图 11 地表冻胀裂缝

Figure 11. Frost heave cracks distributed on the soil surface

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图 12 不同环境温度下基础的荷载-位移曲线

Figure 12. Load-displacement curves of the test foundations under different ambient temperatures

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图 13 试验基础的抗拔极限承载力与环境温度关系曲线

Figure 13. Relation curve between the ultimate uplift capacity of the test foundation and ambient temperature

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图 14 试验结束后地表裂缝分布(-15℃)

Figure 14. Distribution of surface cracks after the test (-15℃)

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表 1 地基土样的物理力学指标

Table 1. Physical and mechanical indexes of the soil sample

指标	数值
相对密度	2.5
含水率/%	10.4
密度/(g·cm^-3)	1.5
液限/%	25.6
塑限/%	15.1
黏聚力/kN	5.9
内摩擦角/(°)	10.4
冻胀率/%	6.2

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表 2 地基土样中可溶盐质量分数

Table 2. Percentage content of soluble salt in the soil sample

指标	w_B/%
Na⁺	0.015 6
K⁺	0.020 9
Mg²⁺	0.014 5
Ca²⁺	0.30
SO₄^2-	0.85
Cl^-	0.038 2

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表 3 本次模型试验的相似参数

Table 3. Similar parameters of these model tests

参数	几何比C_l	时间比C_t	应力比C_σ	应变比C_ε
数值	1∶10	1∶100	1	1

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表 4 3种不同温度下试验基础抗拔极限承载力及极限位移

Table 4. Ultimate uplift capacity and ultimate displacement of the test foundation at three different temperatures

参数	-5℃	-10℃	-15℃
抗拔极限承载力/kN	27	35	45
极限位移/mm	31	34	44

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