Arid Zone Research ›› 2023, Vol. 40 ›› Issue (10): 1637-1643.doi: 10.13866/j.azr.2023.10.10

• Land and Water Resources • Previous Articles     Next Articles

Influence of freezing and thawing on the shear resistance of meandering riverbank soil in the Yellow River source region

LIU Guosong1(),ZHU Haili1,2(),ZHANG Yu1,LIU Yabin1,2,LI Guorong1,2   

  1. 1. Key Laboratory of Cenozoic Resources and Environment on the Northern Margin of the Qinghai-Tibet Plateau, Xining 810016, Qinghai, China
    2. Department of Geoprofessions & Geological Engineering, Qinghai University, Xining 810016, Qinghai, China
  • Received:2022-12-24 Revised:2023-07-31 Online:2023-10-15 Published:2023-11-01

Abstract:

Soil shear resistance in the Riparian zone directly affects riverbank stability. Furthermore, the influence of freezing and thawing on the structure and mechanical properties of alpine meadow soils is directly related to the collapse frequency and lateral migration of the river bank in the source region of the Yellow River. To investigate the change rules and generation mechanisms of the root bearing soil mass, the shear strength index in the meandering Riparian zone of the source region of the Yellow River under the effects of freezing and thawing were assessed. The subsequent impacts of different root contents on the soil mass shear strength index were also determined using an indoor freeze-thaw direct shear test with remolded soil. The experimental results show that plant roots can significantly and increasingly enhance soil cohesion, which can range from 2.7% to 77.9%. Variations in the internal friction angle with root content were not significant. The freeze-thaw cycle weakens soil cohesion, especially in the early stages. The maximum decrease in cohesion of 19.0% occurred with three freeze-thaw cycles, after which the changes stabilized, while the internal friction angle showed a slight increasing trend. The effects of the freeze-thaw action on the shear strength index of the rooted soil is smaller than that of the plain soil. Under the same freeze-thaw frequency conditions, the decrease in cohesion of the rooted samples was found to be smaller than that of the plain soil samples. The root systems of meadow plants can block the changes in soil temperature, reduce the decrease in soil cohesion, and increase with the root content. When the root content reaches 11%, its weakening effect on soil cohesion is 4.2%-27.7% less than that of plain soil. The Riparian zone, as the source area of the Yellow River, should strengthen the protection of riverside meadow vegetation, maximize the role of the root system in enhancing Riparian stability, and protect river ecology.

Key words: source region of the Yellow River, freeze-thaw cycle, root-soil composite, cohesive force, Riparian alpine meadow