水下根土复合体原位剪切装置设计与试验

针对现有原位剪切装置不具备防水功能，试验时难以保证推力匀速进给和推力及对应位移数据的同步采集等问题，为了能在水下进行原位剪切试验来测定植物水下根系的固土能力，结合水下原位剪切的特点，设计一种水下根土复合体原位剪切装置。剪切装置由剪切系统、液压系统、数据采集系统和取样框等组成。该装置能在水下正常工作，试验时推力进给匀速，速度可调可控，能同步自动实时采集、读取、记录、存储数据，并绘制剪应力—位移关系曲线。野外试验表明水下素土的抗剪强度为4.23 kPa，是陆上的74.9%，风车草、花叶芦竹根土复合体的水下抗剪强度分别为17.52 kPa和1438 kPa，是陆上相同RAR根土复合体的56.7%、44%。仿真分析及试验结果表明该剪切装置强度、刚度、精度、稳定性和可靠性均满足使用要求，且能较好的测定水下根系的固土能力。

Design and test of in situ shearing device for underwater root soil complex

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.