集矿机履齿行走作用下深海底质土加载速率效应研究

本项目瞄准深海土力学领域国际研究前沿，面向我国深海资源开发中长期发展战略需求，针对目前深海底质土测试过程中忽略加载速率效应问题（U型曲线效应），首次综合运用流变理论、接触理论、计算流体理论和离散元理论，开展集矿机履齿行走作用下深海底质土加载速率效应研究。利用流变理论和接触理论，结合原子力显微镜二次开发平台，针对太平洋C-C矿区土颗粒在海水环境中的细观流变特性开展研究，同时考虑深海高压高盐环境对颗粒间胶结特性影响，建立含流变和胶结特性的细观接触力学模型；基于离散元+计算流体力学平台，开发含流变和胶结特性的细观接触力学计算程序，结合高速加载三轴试验平台，分析不同加载速率下土中孔隙水压力的变化，揭示深海底质土加载速率效应产生机理及影响因素，建立精确的水-力耦合非线性率效应本构模型，获得最佳和最危险行走速度区间，以保障集矿机行走安全。本研究结果对促进我国深海采矿技术进步具有重要的理论和实际意义。

This project focuses on the international cutting edge of deep-sea sediment mechanics, and aims at the mid- and long-term development strategic needs of deep-sea resource development. Since loading rate effect (U-shaped curve effect) was not considered under current deep-sea sediment testing process, rheological theory, contact theory, computational fluid theory and discrete element theory are carried out comprehensively to study on the rate effect of deep-sea sediment under the walking action of mining machine. Based on the second-development platform of the Atomic Force Microscope, the meso rheological characteristics of the deep-sea soil particles from the Pacific C-C mining area would be studied in the seawater environment using the rheological theory and contact theory, meanwhile the bonding characteristics between particles produced by the high pressure and high salt deep-sea environment would be studied to establish meso contact mechanics models of particles with rheological and bonding characteristics. Then meso-mechanical programs of particles with rheological and bonding characteristics would be developed on the discrete element platform, and water pressure in deep-sea sediment would be analyzed at different loading rates based on the coupling platform of discrete element theory and computational fluid theory. Combining with high-speed triaxial experiment platform, mechanism and influencing factors of rate effect on deep-sea sediment would be revealed and an accurate constitutive model of hydro-mechanical nonlinear rate effect would be established to obtain the best and dangerous walking speed range, which guarantees the safety of the mining machine. The results of this study have important theoretical and practical significance for promoting the development of deep-sea mining technology in China.