| 干湿过程中花岗岩残积土抗拉强度变化研究 |
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| 引用本文： | 汤连生,王昊,孙银磊,刘其鑫.干湿过程中花岗岩残积土抗拉强度变化研究[J].岩土力学,2022,43(7):1749-1760. |
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| 作者姓名： | 汤连生 王昊 孙银磊 刘其鑫 |
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| 作者单位： | 1. 中山大学 地球科学与工程学院，广东 珠海 519082；2. 中山大学 南方海洋科学与工程广东省实验室（珠海），广东 珠海 519082；
3. 中山大学 广东省地球动力作用与地质灾害重点实验室，广东 珠海 519082 |
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| 基金项目： | 国家自然科学基金(No.41877229,No.42102303)；;广东省自然科学基金(No.2018B030311066,No.2019A1515010554)；;中国博士后科学基金(No.2019M663241)~~； |
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| 摘 要： | 利用自制的土体直拉强度测试仪，研究了重塑花岗岩残积土在不同含水率下、增湿过程和干燥过程中抗拉强度的变化规律，并从胶结力和湿吸力的角度讨论了抗拉强度变化规律的微观机制。结果表明：不同含水率条件下抗拉强度随含水率增加呈现先增后减，峰值两侧呈较好的指数规律；增湿过程中抗拉强度随含水率增加呈先增后减趋势，峰值两侧为一次函数规律；干燥过程中抗拉强度随含水率降低出现指数增加阶段、平稳阶段和小幅降低阶段3个阶段，其抗拉强度峰值为不同含水率条件下抗拉强度的4倍。花岗岩残积土在不同含水率和增湿过程中的抗拉强度的变化主要受湿吸力控制，而干燥过程中抗拉强度变化的同时受湿吸力和胶结力的控制，且胶结力对抗拉强度的贡献超过70%。土体的干燥开裂过程对应干燥过程中抗拉强度变化的几个阶段，干燥时湿吸力是土体内部拉应力的来源，这说明湿吸力既是抗拉强度的贡献者，同时也是抗拉强度的破坏者。该研究结果从另一种角度解释了土体抗拉强度的形成来源及其变化的主控因素。
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| 关 键 词： | 抗拉强度 花岗岩残积土 干湿过程 湿吸力 胶结力 干燥开裂 |
| 收稿时间： | 2021-10-19 |
| 修稿时间： | 2022-03-30 |
Change of tensile strength of granite residual soil
during drying and wetting |
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| TANG Lian-sheng,WANG Hao,SUN Yin-lei,LIU Qi-xin.Change of tensile strength of granite residual soil
during drying and wetting[J].Rock and Soil Mechanics,2022,43(7):1749-1760. |
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| Authors: | TANG Lian-sheng WANG Hao SUN Yin-lei LIU Qi-xin |
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| Institution: | 1. School of Earth Sciences and Engineering, Sun Yat-sen University, Zhuhai, Guangdong 519082, China;
2. Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Zhuhai, Guangdong 519082, China;
3. Guangdong Provincial Key Lab. of Geodynamics and Geohazards, Sun Yat-sen University, Zhuhai, Guangdong 519082, China |
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| Abstract: | Using the self-developed soil tensile strength tester, the tensile strength variations of the remolded granite residual soil with water content in wetting or drying process were studied. The microscopic mechanism of the tensile strength variation was investigated through the theories of cementation force and absorbed suction. The results show that the tensile strength first increases and then decreases with increasing the water content, and the relationships between tensile strength and water content on both sides of the peak value can be expressed by exponential functions. In the process of humidification, the tensile strength first increases and then decreases with the increase of moisture content, and the data on both sides of the peak are fitted by linear functions. In the drying process, three stages can be identified in the tensile strength, i.e. exponential increase stage, stable stage and slight decrease stage, the peak tensile strength is 4 times of tensile strengths at different moisture contents. The change of tensile strength of granite residual soil in the process of humidification with different water contents are mainly controlled by absorbed suction. While the change of tensile strength in the drying process is controlled by both absorbed suction and cementation force, the contribution of the cementation force to the tensile strength is more than 70%. The dry cracking process of soil corresponds to several stages of the tensile strength change in the drying process. In the drying process, absorbed suction is the source of the internal tensile stress of soil, indicating that absorbed suction is not only a contributor to tensile strength, but also a destroyer of tensile strength. The results of this study explain the formation source of the tensile strength of the soil and the main controlling factors of its change from another perspective. |
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| Keywords: | tensile strength granite residual soil dry and wet process absorbed suction cementation force dry cracking |
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