Arid Zone Research ›› 2022, Vol. 39 ›› Issue (3): 900-907.doi: 10.13866/j.azr.2022.03.23

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Straight root tensile properties of Salix psammophila in response to cyclic loading

HU Jinghua1(),LIU Jing1(),BAI Luyi1,ZHANG Xin2,LAN Pengbo1,YUAN Yanan1   

  1. 1. College of Desert Contral Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010019, Inner Mongolia, China
    2. Institute of Water Resources for Pasturing Area of the Ministry of Water Resources, Hohhot 010020, Inner Mongolia, China
  • Received:2021-04-30 Revised:2021-08-17 Online:2022-05-15 Published:2022-05-30
  • Contact: Jing LIU E-mail:hujinghua111@163.com;ljing58@126.com

Abstract:

To clarify mechanical properties of straight roots in response to repeated loading and unloading induced by simulated high wind drawing, an axial cyclic load test was applied to straight roots of Salix psammophila. These roots had a diameter of 1-5 mm in the Shendong mining area and a TY8000 servo-type strong force was used to reveal the soil-fixing ability of plants in wind-eroded areas after their roots were repeatedly stressed by strong long-term winds. Results show the following: (1) the tensile force of straight roots after cyclic loading was positively correlated with the diameter based on a power function; the tensile strength after cyclic loading was negatively correlated with root diameter based on a power function, which was similar to the relationship between tensile force, tensile strength, and root diameter under a monotonic load. (2) Compared with the monotonic load, the tensile force and tensile strength after cyclic loading of straight roots of all diameters were significantly enhanced (P<0.05), and the tensile force and tensile strength of 1-2 mm, 2.5-3.5 mm, and 4-5 mm roots increased by 60%, 60%, 48%, 50%, and 31%, 32%, respectively. (3) In the cycle process, the force-displacement curve of straight roots showed obvious cycle characteristics with increasing cycle number; the hysteresis loop spacing is gradually close to closing; and as the area decreases, the capacity of resistance to plastic deformation becomes worse, which tends to be stable. The accumulated elongation of straight roots increases with increasing cycle number, which can be divided into a rapid growth stage and a slow growth stage. (4) The elastic stress, ultimate stress, and elasticity modulus of straight roots was negatively correlated with root diameter after monotonic load and cyclic load, and the accumulated elastic strain and ultimate strain have no relationship with root diameter. The elastic stress, ultimate stress, and accumulated elastic strain after cyclic loading of all diameters was enhanced, the ultimate strain was monotonic load > cyclic load, and the elastic modulus has no relationship under different loads.

Key words: straight roots, cyclic load, tensile strength, deformation characteristic, Salix psammophila