冻融循环作用下膨胀土边坡稳定性模型试验研究
张莹莹1,杨忠年1,时 伟1,李国玉3,涂志斌1,凌贤长1,2

(1. 青岛理工大学 土木工程学院,山东 青岛 266033; 2. 哈尔滨工业大学 土木工程学院,黑龙江 哈尔滨 150001; 3. 中国科学院西北生态环境资源研究院 冻土工程国家重点实验室,甘肃 兰州 730000)

膨胀土边坡; 冻融循环; 位移; 土压力; 含水率

Model test study on the stability of expansive soil slope under freeze-thaw cycle
ZHANG Yingying, YANG Zhongnian, SHI Wei, LI Guoyu, TU Zhibin, LING Xianzhang

(1.School of Civil Engineering,Qingdao university of technology, Qingdao 266033, China; 2.School of Civil Engineering,Harbin Institute of Technology, Harbin 150001, China; 3. National key laboratory of tundra engineering, Northwest Institute of Eco-environment and Resources, Lanzhou 730000, China)

Expansive soil slope; Freeze-thaw cycle; Displacement; Soil pressure; The moisture content

DOI: 10.15986/j.1006-7930.2020.02.015

备注

采用重塑膨胀土进行室内边坡模型试验,研究膨胀土边坡在冻融循环作用下边坡模型的位移,土压力,含水率和孔隙压力的变化特性,反应冻融循环对膨胀土边坡稳定性影响.试验发现,冻融循环作用下膨胀土边坡表面裂隙由初始数量较少的直线型长裂隙向数量较多的网络状短裂隙发展,对沿深度方向上的裂隙发育亦存在显著影响.土压力在单次冻融中表现随温度降低土压力增大,反之亦然.边坡在冻融过程中始终表现冻缩融胀,但整体上表现出向临空面逐渐变形的趋势.且单个冻融循环周期内位移变化速率与温度绝对值呈正相关关系.含水率在单个冻融循环周期内呈现随温度降低而降低,温度升高反之,随试验进行含水率在深度方向表现出明显水分迁移现象.孔隙压力随温度降低先小幅度升高后大幅度下降,温度升高孔隙压力先升高后下降.孔隙压力受温度传导速度影响很大.首次冻融对边坡变形、含水率和孔隙压力影响很大,随着试验进行其变化都会趋于稳定.

The reconstituted expansive soil was used for the indoor slope model test to study the displacement, soil pressure, moisture content and pore pressure of the expansive soil slope model under the action of freeze-thaw cycle, and to reflect the influence of freeze-thaw cycle on the stability of the expansive soil slope.It is found that the surface fissures of expansive soil slope under the action of freezing-thawing cycle develop from linear long fissures with few initial number to network short fissures with more number, which also has a significant influence on the development of fissures along the depth direction. Soil pressure in single freezing-thawing behavior increases with temperature decrease, and vice versa. In the process of freezing-thawing, the slope always shows freezing-shrinkage and thawing heave, but on the whole, it shows the tendency of deformation to the surface. Moreover, the displacement change rate in a single freezing-thawing cycle positively correlated with the temperature absolute value. The moisture content in a single freezing-thawing cycle decreases with the decrease of temperature, and vice versa. The moisture content in the depth direction shows an obvious water transfer phenomenon.With the decrease of temperature, the pore pressure increases at first and then decreases greatly, while the pore pressure increases at first and then decreases when the temperature increases.Pore pressure is greatly affected by temperature conduction velocity. The first freezing-thawing has a great influence on slope deformation, moisture content and pore pressure.