人工冻融红黏土抗剪强度特性试验研究
1. 东华理工大学, 土木与建筑工程学院, 江西南昌 330013
2. 中铁十六局集团路桥工程有限公司, 北京 101500
3. 江苏开放大学, 建筑工程学院, 江苏南京 214257
| 摘 要： | 人工地层冻结法常用于盾构隧道端头地层加固、联络通道开挖等富水地层加固，为探讨人工冻结法施工过程中红黏土经历常温、冻结和冻融后三种状态的抗剪强度变化规律，采用常规直剪试验，开展不同含水率、冻结温度和三种不同冻融状态下的人工冻融红黏土抗剪强度特性试验研究，揭示不同条件下土体抗剪强度变化规律。研究结果表明：(1) 冻结状态下红黏土抗剪强度显著提高，较常温状态下提高5.7倍，且土体内摩擦角和黏聚力均增加；(2) 冻结状态红黏土试样抗剪强度随含水率增加呈先增大后减小，在含水率30%时最大抗剪强度达550kPa；且冻结温度越低，抗剪强度越大，在-15°C冻结状态下最大抗剪强度达580kPa；红黏土经冻融后，其结构被扰动，灵敏度提高，抗剪强度受含水率和冻结温度影响较常温状态试样变化更为明显；(3) 冻结温度越低，冻结状态下红黏土的抗剪强度越大；冻结状态红黏土最大抗剪强度、黏聚力和内摩擦角显著增加；红黏土冻融后抗剪强度较常温状态有所降低。研究结果对指导红黏土地层开展人工冻结加固具有一定的指导意义。 |
| 关 键 词： | 人工地层冻结法; 红黏土; 抗剪强度; 直接剪切试验 |
| DOI： | 10.57237/j.cear.2023.03.001 |
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收稿日期: 2023-08-23
接受日期: 2023-09-20
在线出版日期: 2023-10-09
Experimental Study on Shear Strength Characteristics of Artificial Freeze-thaw Red Clay Soil
1. School of Civil and Construction Engineering, Donghua University of Science and Technology, Nanchang 330013, China
2. China Railway 16th Bureau Group Road and Bridge Engineering Co, Beijing 101500, China
3. Construction Engineering College, Jiangsu Open University, Nanjing 214257, China
| Abstract: | Artificial ground freezing method is commonly used in shield tunnel end ground reinforcement, contact channel excavation and other water-rich ground reinforcement, in order to explore the construction process of artificial freezing method of red clay through room temperature, freezing and freezing and thawing three states of shear strength change rule, using conventional straight shear test, to carry out the different moisture content, freezing temperature and the three different freezing and thawing state of artificial freezing and thawing of the red clay shear strength characteristics of experimental research to reveal different conditions of the change rule of the soil shear strength. Under different conditions, the soil shear strength change rule. The results show that: (1) The freezing state of red clay shear strength increased significantly, compared with the room temperature state increased by 5.7 times, and the friction angle and cohesion within the soil are increased. (2) The freezing state of red clay specimens shear strength with the increase of water content is first increased and then decreased, in the water content of 30% of the maximum shear strength of 550kPa. And the lower the freezing temperature, the greater the shear strength, in -15°C freezing state maximum shear strength of 550kPa. The maximum shear strength reaches 580kPa in -15°C freezing condition. After freezing and thawing, the structure of red clay is disturbed, the sensitivity is increased, the shear strength is affected by the water content and freezing temperature, which is more obvious than the change of the normal temperature state specimen. (3) The lower the freezing temperature is, the greater the shear strength of red clay in the freezing condition is. The maximum shear strength, the adhesive force and the angle of internal friction of red clay in the freezing condition are increased significantly. After freezing and thawing the shear strength of red clay is reduced compared with the normal temperature state. After freezing and thawing, the shear strength of red clay decreased. The results of the study are of some significance in guiding the artificial freezing reinforcement of red clay strata. |
| Keywords: | Artificial Ground Freezing Method; Red Clay; Shear Strength; Direct Shear Test |
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