Study On Pull-Out Model Tests For Simulative Roots

As a new type of slope protection technology, the vegetation protection has been extensively studied in recent years. At present, the shear strength of roots as a starting point, studies based on the finer roots, the higher tensile strength, got the improvement of the shear strength by plant roots. In practical engineering, with the slides happening, the fine roots are easily broken because the tensile is over the tensile strength. Usually, the thick roots play an important role on the protection of the slope. According to the experiment study on the pull-out of the tree roots, the influence of the root length、shape、loading angle to the root’s pull-resistance was analysed, as well as the interaction between roots and soils,and then the test results were compared with the theoretical results. The main results and conclusions are presented as follows:1.In the 0-80cm area, the skin friction of the roots increased and then declined with the increase of the root burial depth. When the vertical single root under the action of a force, the location of the maximum skin friction in the root below ground 0.33 to 0.50 times the length of root. In the 20-60cm area, the skin friction is larger than other areas, and is the key component in the pulling resistance of roots.2. Aimed at the vertical single root, the Load direction remains the same, the limiting load of the single root increases with the increase of the root length; when the root length remains the same, the limiting load of the single root increases with the increase of the loading angle.3. The roots which contain a single lateral root, under the action of a vertical load, when the length of the lateral root and main root remains the same, the limiting load increases with the increase of the included angle, the lateral root greatly enhances thelimiting load of the roots.4. The roots which contain symmetrical lateral roots, under the action of a vertical load, when the length of the lateral roots and included angle remains the same, the limiting load increases with the increase of the main root’s length; when the length of the lateral roots and main root remains the same, the limiting load increases with the increase of the included angle;5. When the sum length of the entire roots keeps the same, the roots shape is the key factor influencing the limiting load of the entire roots. The more complex shapes, the greater the limiting load of the entire roots.