| 摘要: |
| 以天津滨海新区的软黏土为研究对象，制备了4种初始含水率的水泥改良软黏土试样，并对其进行了不同冻融循环次数下的无侧限抗压强度（UCS）试验和孔隙分析.结果表明：随着冻融循环次数的增大，试样的无侧限抗压强度逐渐减小，强度衰减主要集中在前期1～3次冻融循环过程中；相同冻融循环次数作用下，试样初始含水率越大，其强度损失率越大；试样的孔隙分布特征受冻融循环次数和初始含水率影响，随初始含水率增大，其孔隙分布逐渐由小孔隙分布区向较大孔隙分布区演变；低饱和度状态下，冻融会引起土体局部孔隙收缩，但同时诱发裂隙产生；高饱和度状态下，冻融会引起土体结构疏松.总体而言，冻融循环作用会引起水泥改良软黏土细观结构发生明显损伤，最终导致其宏观力学强度逐渐衰减.因此，在工程实践中需要进一步关注水泥改良软黏土的后期强度，并严格控制其初始填筑时的湿度状态. |
| 关键词: 软黏土 冻融循环 强度 微观机制 |
| DOI：103969/j.issn1007 9629201702009 |
| 分类号: |
| 基金项目:湖北省自然科学基金资助项目(2014CFB664)；国家自然科学基金资助项目(51579137) |
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| Performance Evolution of Cement Improved Soft Clay under Freeze Thaw Cycles |
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TAN Yunzhi1, WU Jun1, HUANG Longbo1, WANG Hongxing1, ZUO Qingjun1, YI Juran2
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1.Key Laboratory of Geological Hazards on Three Gorges Reservoir Area, Ministry of Education, Three Gorges University, Yichang 443002, China;2.Yichang Langtian New Building Materials Co., Ltd., Yichang 443132, China
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| Abstract: |
| The samples were prepared with four kinds of initial moisture content, which were collected in beach area of Tianjin. Unconfined compressive strength(UCS) test and pore size analysis were carried out on the samples under different times of freeze thaw cycles. The UCS evolution process and pore size distribution curves were measured. The results show that the UCS of samples reduces while freeze thaw cycles increase, and the decrease is significant under the initial 13 cycles. Meanwhile, the higher the initial moisture content of samples, the larger the strength loss ratio under the same freeze thaw cycles. The pore size distribution curves of samples are determined by initial moisture content and freeze thawing cycles. The pore size distribution areas change from microscopic to macroscopic range with increasing initial moisture content. When the treated soils are at low saturated degree state, pores would shrink and the cracks appear due to freeze thaw cycles. However, at high saturated degree stage, the structure of soils would become porous under the effect. Overall, the micro pore structure is damaged apparently due to freeze thaw effect, and ultimately results in gradual decrease of macro strength. Hence, it is necessary to pay attention to the long term strength of the cement improved soft clay, and keep suitable moisture content during filling time. |
| Key words: soft clay freeze thaw cycle strength microscopic mechanism |
