An outdoor drawing test study of the root soil interaction force for a small tree root system

Small trees have a very high proportion in slope ecological protection. A study of the mechanism of slope protection and influence factors of a small tree root system are of important theoretical and practical significance for further improvement of the slope protection technology. On the basis of domestic and foreign research achievements, the influence of moisture content and root geometric parameters on the strengthening ability of slope soil is examined by the outdoor drawing experiment in red clay ground with the pinus elliottii root system. The results show that moisture content of the surface soil is greater than that in the deep soil after heavy rainfall condition and moisture content of the root soil is less than that in the nature soil. It is found that the small tree root system helps the water to infiltrate in the slope. The maximum drawing force increases first and then decreases with the increasing moisture content as the trend of the quadratic function; the maximum drawing force increases monotonically with the increasing root volume over all the performance, but when moisture content is 22% and 24%，the maximum drawing force decreases first and then increases with the increasing root volume. The pullout force displacement curve fluctuates greatly under different volume or moisture content of the plant root.