关键词: 水下, 根土复合体, 原位剪切试验, 剪切装置

Abstract: In view of the problems that the existing insitu shearing device does not have the waterproof function, it is difficult to ensure the constant feed of the thrust and the synchronous acquisition of the thrust and corresponding displacement data during the test, in order to conduct insitu shear tests under water to determine the soilfixing ability of plant roots under water, combined with the characteristics of underwater insitu shearing, an underwater rootsoil composite insitu shearing device is designed. The shearing device is composed of shearing system, hydraulic system, data acquisition system and sampling frame. The device can work normally under water. During the test, the thrust is fed at a constant speed, and the speed is adjustable and controllable. It can automatically collect, read, record and store data in real time, and draw the shear stressdisplacement relationship curve. The field experiments show that the shear strength of underwater plain soil is 4.23 kPa, which is 74.9% on land, and the underwater shear strength of Cyperusalternifolius L. and Arundodonax var. versicolor rootsoil composite is 17.52 kPa and 14.38 kPa respectively, which is 56.7% and 44% of the same RAR rootsoil complex on land. Simulation analysis and experimental results show that the strength, stiffness, accuracy, stability and reliability of the shearing device meet the operating requirements, and can better measure the soil consolidation capacity of underwater roots.

Key words: underwater, rootsoil complex, insitu shear tests, shearing device