College of Geology and Environment, Xi’an University of Science and Technology
Geological Research Institute for Coal Green Mining, Xi’an University of Science and Technology
Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation

植物根系能提高边坡稳定性和防止水土流失，研究选取紫花苜蓿−黄土复合体为研究对象，通过PVC管人工种植获取紫花苜蓿−黄土复合体试样，并采用三轴压缩试验测定紫花苜蓿−黄土复合体抗剪强度指标并分析其时间效应，对比分析了围压及含水率对紫花苜蓿−黄土复合体抗剪强度的影响作用。结果表明：与素黄土相比，紫花苜蓿−黄土复合体抗剪强度显著提高。随着紫花苜蓿生长期（60、90、120、150 d）的增加，紫花苜蓿−黄土复合体的黏聚力显著增加；在低围压状态下，不固结不排水（UU）试验中不同生长期紫花苜蓿−黄土复合体试样黏聚力较素黄土分别增加了7.02%、18.81%、26.09%和36.41%，固结不排水（CU）试验中不同生长期紫花苜蓿−黄土复合体试样黏聚力较素黄土分别增加了27.62%、50.87%、77.62%和158.14%；在高围压状态下，不固结不排水（UU）试验中紫花苜蓿−黄土复合体试样黏聚力显著高于素黄土且随生长期增加而增大，但固结不排水（CU）试验中无明显规律。此外，对于根系生长较浅的草本植物来说，选择低围压状态进行三轴压缩试验更符合实际情况；同一生长期饱和含水率状态下的紫花苜蓿−黄土复合体抗剪强度指标显著低于天然含水率的，且随着紫花苜蓿生长期增加，饱和含水率状态的黏聚力较天然含水率状态的降低幅度越来越大；采用PVC管人工种植方式制备的紫花苜蓿−黄土复合体试样更加有利于模拟出根-土之间的相互作用。

The alfalfa-loess composite, obtained by artificial planting in PVC tubes, was selected as the research object. Through triaxial compression tests, the time effect of shear strength change of alfalfa-loess composite was analyzed, and the effects of confining stress and water content on the shear strength of alfalfa-loess composite were compared. The results shown that the shear strength of alfalfa-loess complex was significantly enhanced compared to the plain loess. The cohesion of the alfalfa-loess composite significantly increased with increasing growth period of alfalfa (60 days, 90 days, 120 days and 150 days). Under a lower confining stress, the cohesion of alfalfa-loess composite with different growth periods in unconsolidated and undrained (UU) test increased by 7.02%, 18.81%, 26.09% and 36.41%, respectively, compared with that of plain loess, while that in the unconsolidated and undrained (CU) test increased by 27.62%, 50.87%, 77.62% and 158.11%, respectively. Under a higher confining stress, the cohesion of alfalfa-loess composite in unconsolidated and undrained (UU) test was significantly higher than that of plain loess, and increased with the growth period, but there was no obvious pattern in consolidated and undrained (CU) test. In addition, the case of herbaceous plants with shallow root growth was more practical to conduct triaxial test in a lower confining stress. The shear strength index of alfalfa-loess composite in the saturated water content was significantly lower than that in the natural water content in the same growth period. As the growth period of alfalfa increased, the decrease in cohesion in the saturated water content was more obvious than that in natural water content. Artificial planting of alfalfa-loess composite using PVC tubes was more conductive to modeling the interaction between roots and soil.

陕西省重点研发计划资助项目（2020SF-379），宁夏回族自治区重点研发计划资助项目（2022BEG03052）

毛正君，耿咪咪，毕银丽，等. 紫花苜蓿−黄土复合体抗剪强度时间效应研究[J]. 煤炭科学技术，2023，51（11）：234−247.

MAO Zhengjun，GENG Mimi，BI Yinli，et al. Study on the time effect of shear strength of alfalfa-loess composite[J]. Coal Science and Technology，2023，51（11）：234−247.