| 循环荷载下水泥土桩复合单元体变形特性及其地基长期沉降计算方法 |
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| 引用本文： | 张振,郑文强,叶观宝,陈勇.循环荷载下水泥土桩复合单元体变形特性及其地基长期沉降计算方法[J].中国公路学报,2022,35(11):21-29. |
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| 作者姓名： | 张振 郑文强 叶观宝 陈勇 |
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| 作者单位： | 1. 同济大学 土木工程学院地下建筑与工程系, 上海 200092;2. 同济大学 岩土及地下工程教育部重点实验室, 上海 200092;3. 上海勘察设计研究院(集团)有限公司, 上海 200093 |
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| 基金项目： | 国家自然科学基金项目（41772281，41972272）；上海市科技计划项目（22ZR1466600） |
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| 摘 要： | 对于软土地区的路基工程，若路基处理不当，在长期交通荷载作用下，容易导致服役期路面开裂、不均匀沉降等问题。水泥土搅拌桩法是软土地区最常用的路基加固方法之一。研究循环荷载下水泥土桩复合地基的变形特性，对于指导交通荷载下软土地基长期沉降控制具有重要意义。然而，现有研究主要集中在软土和水泥土单一介质，对于水泥土桩复合体的研究较少。通过开展水泥土桩复合单元体大型动三轴试验，分析围压、静偏应力和置换率等因素对水泥土桩复合体累积塑性应变的影响。研究结果表明：循环荷载下水泥土桩复合体累积塑性显著小于软土，且应变随围压、动应力比及静偏应力的增大而增大，随置换率的增大而减小；静偏应力的增加会导致复合单元体临界动应力比的减小。基于试验结果，建立了水泥土桩复合体长期沉降计算方法。结合现代有轨电车算例，分析交通荷载作用下软土路基以及经水泥土桩法处理后的路基长期沉降结果。计算结果表明，采用水泥土桩法可有效减小软土路基长期沉降。
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| 关 键 词： | 道路工程 长期沉降 大型动三轴试验 水泥土桩复合体 计算方法 分级循环加载 |
| 收稿时间： | 2022-03-21 |
Deformation and Long-term Settlement Calculation Method of Unit Cell of Soil-cement Column-reinforced Soft Soil Under Cyclic Loading |
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| ZHANG Zhen,ZHENG Wen-qiang,YE Guan-bao,CHEN Yong.Deformation and Long-term Settlement Calculation Method of Unit Cell of Soil-cement Column-reinforced Soft Soil Under Cyclic Loading[J].China Journal of Highway and Transport,2022,35(11):21-29. |
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| Authors: | ZHANG Zhen ZHENG Wen-qiang YE Guan-bao CHEN Yong |
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| Affiliation: | 1. Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China;2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China;3. SGIDI Engineering Consulting (Group) Co. Ltd., Shanghai 200093, China |
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| Abstract: | For the road engineering in soft soil regions, if the subsoil is not reasonably treated, it is easy to induce engineering problems such as pavement cracking and differential settlement in service under long-term traffic loading. Soil-cement column is one of the most commonly-used methods to improve soft soil. There has been increasing focus on studying the deformation of soil-cement column-reinforced soft soil under cyclic loading. It has significance for controlling the long-term settlement of soft soil under traffic loading. Current researches have been mainly focused on the dynamic characteristics of single material of soil or soil-cement, but few studies have been concentrated on the dynamic characteristics of the soft soil with soil-cement column as a composite. This study conducted a series of large-scale dynamic triaxial tests to investigate the following factors of confining pressure, static deviatoric stress and area replacement ratio on the accumulative plastic strain of the composite. The results show that the accumulative plastic strain of the composite under cyclic loading is significantly less than that of soft soil. The accumulative plastic strain of the composite increases with the increase of confining stress, dynamic stress ratio and static deviatoric stress ratio, and it increases with the decrease of area replacement ratio. Increasing static deviatoric stress leads to a reduction of critical dynamic stress ratio. Based on the test results, a method was proposed for calculating the long-term settlement of soft soil with soil-cement column. This method was applied to an example of modern tram for a comparative analysis about the difference of long term settlement between untreated soft soil and soft soil treated by soil-cement column method. The calculation results show that the soil-cement column method cannot ably reduce the long-term settlement of soft soil. |
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| Keywords: | road engineering long-term settlement large-scale dynamic triaxial test composite of soft soil with soil-cement column calculation method multi-staged cyclic loading |
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