水平荷载作用下多花木蓝根系拉拔试验研究

为探索灌木植物根系与土壤界面摩擦力的影响因素,通过改变土壤干密度条件,采用直接施加水平拉拔荷载的方法进行单根拉拔试验,研究了多花木蓝单根的抗拉拔力。结果表明①多花木蓝单根的抗拉拔力与位移关系曲线可分为陡峭上升、陡峭下降和平缓下降3个阶段,在试验开始阶段呈线性关系,随后表现出显著的非线性关系;②在同一土壤干密度条件下,多花木蓝单根的最大抗拉拔力随着根径的增加而呈线性增大趋势,相关系数超过0.9;③当根径一定时,多花木蓝单根的最大抗拉拔力随着土壤干密度的增加而增大;④根在土壤干密度ρ_d为1.35,1.45,1.55 g/cm³时的拉拔破坏模式均表现为摩擦破坏,而土壤干密度ρ_d=1.65 g/cm³,根径r=0.586 mm是根的拉拔破坏模式从摩擦破坏到拉断破坏的临界点,表明当根径r<0.586 mm时,根的破坏模式表现为拉断破坏,而当根径r>0.586 mm时,根的破坏模式表现为摩擦破坏。因此,根径、土壤密度影响根土界面的抗拉拔力。

Pull-out Test of Indigofera amblyantha Craib Root under Horizontal Load

In order to explore factors influencing the shrub plant roots and soil interface friction, we carried out the direct pull-out test on Indigofera Amblyantha Craib root to study its anti-pullout force under different soil dry densities. The results show that (1) the curves of anti-pullout force vs. displacement of the roots can be divided into three phases of steep rise, steep fall and gentle decline, increasing linearly to peak value at the start phase, and then presenting non-linear trend; (2) the maximum anti-pullout force of Indigofera Amblyantha Craib root increases obviously linearly with the increasing of root diameter under the same soil dry density, and the coefficient of correlation reaches 0.9; (3) the maximum anti-pullout force of Indigofera Amblyantha Craib root increases with the increasing of soil dry density with given root diameter, and the modes of pull-out failure of all roots are friction failure when the soil dry density varies from 1.35 g/cm³ to 1.45 g/cm³ and 1.55 g/cm³, while when the density is 1.65 g/cm³, root diameter of 0.586 mm is the critical point from friction failure to tensile failure, which means that the pull out failure mode is tensile failure when the root diameter is less than 0.586 mm, and friction failure when the root diameter is larger than 0.586 mm. Therefore, root diameter and unit weight of soil have influence on the anti-pullout force of root-soil interface.