冻融作用对岸坡土体宏微观特性及岸坡稳定性影响研究  

Effects of freezing-thawing action on the macro-micro properties of bank slope soil and bank stability

作　　者：杨震 冀鸿兰[1] 李超[1] 牟献友[1] 李扒拴 YANG Zhen;JI Honglan;LI Chao;MOU Xianyou;LI Bashuan(College of Water Resources and Civil Engineering,Inner Mongolia Agricultural University,Hohhot 010018,China;Hohhot Tuoketuo County Rural Revitalization Coordinated Development Center,Hohhot 010200,China)

机构地区：[1]内蒙古农业大学水利与土木建筑工程学院,内蒙古呼和浩特010018 [2]呼和浩特市托县乡村振兴统筹发展中心,内蒙古呼和浩特010200

出　　处：《水利学报》2023年第6期706-716,738,共12页Journal of Hydraulic Engineering

基　　金：国家自然科学基金项目(51969020,52169017,51969025);内蒙古自然科学基金重点项目(2022ZD08);2018自治区应用技术研究与开发资金项目(201802104)。

摘　　要：冻融作用是季冻区岸坡失稳破坏的主要原因。以黄河内蒙古什四份子弯道岸坡土体为对象,通过三轴剪切和扫描电镜试验,研究了冻融作用下岸坡土体的宏观和微观特性,并基于强度折减法,对冻融前后岸坡稳定性进行了分析。结果表明:随冻融循环次数增加,土体弹性模量、黏聚力和抗剪强度均呈减小趋势,其中弹性模量大小与含水率成反比,黏聚力在15次冻融后降幅达43.6%~60.04%,内摩擦角无明显变化规律;冻融后土体颗粒真圆度和孔隙概率熵随冻融次数增加先下降后上升,颗粒分形维度变化趋势与之相反,土体定向性和孔隙率呈增大趋势;黏聚力与土体孔隙率和颗粒真圆度相关,特别是与孔隙率呈高度负相关性,且土体微观参数间有明显的自相关性;冻融后岸坡稳定安全系数降幅达41.8%,说明冻融作用会显著降低岸坡稳定性,冻融后岸坡易发生失稳破坏。Freeze-thaw action is the main factor of bank slope instability damage in the seasonal freezing zone.Taking the bank slope soil of Shisifenzi bend in Inner Mongolia of the Yellow River as the research object,the macroscopic and microscopic properties of the bank slope soil under freeze-thaw action were studied by triaxial shear and scanning electron microscope tests,and the stability of the bank slope before and after freeze-thaw was analyzed based on the strength reduction method.The results show that the modulus of elasticity,cohesion and shear strength of the soil decrease with the increase of the number of freeze-thaw cycles,among which the size of the modulus of elasticity is inversely proportional to the moisture content,the cohesion decreases by 43.6%~60.04%after 15 freeze-thaw cycles,and the angle of internal friction has no obvious change pattern.Soil particle roundness and pore probability entropy decreased and then increased with the increase of the number of freeze-thawing,while the change trend of particle fractal dimension is opposite,and soil orientation and porosity showed an increasing trend.Cohesion is correlated with soil porosity and particle roundness,and especially highly negatively correlated with porosity,and there is a significant autocorrelation between soil micro parameters.The stability safety factor of the bank slope after freeze-thaw decreases by 41.8%,indicating that the freeze-thaw action will significantly reduce the stability of the bank slope,and the bank slope is prone to instability damage after freeze-thaw.

关 键 词：冻融循环 抗剪强度指标 微观结构 岸坡稳定性 黄河内蒙古段 

分 类 号：TV871[水利工程—水利水电工程]