摘要
黄土中节理裂隙十分发育,严重影响黄土的力学性质。尤其是对地下采煤引发的黄土滑坡进行评价时,除了需要考虑采矿引起的斜坡变形,还需考虑采煤引起的黄土裂隙化导致的强度劣化问题。本文通过三轴压缩试验研究不同裂隙密度的黄土在不同含水率下的抗剪强度参数变化规律。研究表明:随着裂隙密度的增加,内摩擦角呈明显减小趋势;黏聚力在低含水率下呈减小趋势,在高含水率条件下变化规律不明显。由于裂隙的出现,临近裂隙的土体应力重分布,应力方向发生偏转,垂直于裂隙的应力值趋近于零,主应力差增大,因此临近裂隙的土体发生局部破坏,这种现象的最终宏观表现之一为内摩擦角变小。较低含水率条件下,裂隙的存在,影响了土颗粒之间的连续性,宏观表现为随着裂隙密度的增大,黏聚力值在减小;但随着含水率的增大,水使土体胶结弱化作用加强,裂隙对土颗粒之间连结的影响作用趋弱,宏观上表现为黏聚力随裂隙密度非单调变化。
Fractures in loess are very common,and seriously affect the mechanical properties of loess. In addition to considering the slope deformation caused by mining,the strength deterioration reduced by the fractures in loess must be emphasized during the analysis of the loess landslides caused by underground mining. The shear strength of loess with different density of fractures and different moisture content was studied by triaxial compression test. The research shows that with the increase of fractures density,the friction angle decreases obviously,the cohesive decreases at low moisture content,and the change law is not obvious under high moisture content. Due to the occurrence of the fracture,the stress of the soil adjacent to the fracture was redistributed,the direction of the stress changed,the stress value perpendicular to the fracture was approximately zero,the difference between the maximum and minimum principal stress increased,therefore,the soil near fracture partially destroyed. One of the final macro manifestations of this phenomenon was that the internal friction angle reduced. Under the condition of low moisture content,the fractures affect the continuity between soil particles,the macro performance is the decrease of cohesion value. With the increase of the water content,the weakening effect of soil cement caused by water is strengthened. The effect of fractures on the connection between soil particles was weakened. Macroscopically,the cohesion varies non-monotonously with the change of fracture density.
作者
成玉祥
曹宝宝
张大伟
CHENG Yu-xiang;CAO Bao-bao;ZHANG Da-wei(College of Geology Engineering and Geomatics,Chang'an University,Key Laboratory of Western China's Mineral Resources and Geological Engineering,Ministry of Education;Shaanxi Nuclear Industry Engineering Survey Institute Co.Ltd.,Xi'an 710054,China)
出处
《科学技术与工程》
北大核心
2019年第28期284-289,共6页
Science Technology and Engineering
基金
国家自然科学基金(41672255)
中央高校基本科研业务费专项资金(300102268202)资助
关键词
裂隙黄土
抗剪强度
裂隙密度
三轴试验
fractured loess
shear strength
fracture density
triaxial compression test
