多金属结核采矿对海底沉积物扰动的数值分析

Numerical Simulation on the Disturbance of Polymetallic Nodule Mining to Marine Sediments

通过分析多金属结核采矿系统和结核海底赋存特征,发现多金属结核采矿对海洋环境造成的所有扰动中,采集头和集矿机产生的扰动最直接、影响最大。针对海底沉积物被扰动、沉积物颗粒迁移和扩散过程进行了数值分析。利用Fluent软件SIMPLE算法仿真沉积物颗粒受扰动后的运动,应用DPM模型追踪扰动导致的颗粒运动,计算了沉积物颗粒扩散浓度的变化。仿真结果表明:伴随着多金属结核采矿,沉积物被扰动到海洋底层水中,先在扰动源后方形成云团,之后在扰动源前方形成云团,随着云团的扩散、融合,云团个数减少,云团内的颗粒浓度降低,30min后浓度变化趋于稳定。由此可以了解沉积物被扰动后对海底环境的影响,为后续扰动监测提供监测参数选取和传感器时间、空间布设依据。

The geotechnical features of polymetal l ic nodules and mar ine sediments in China cont ract mining area has been analyzed. Also the working characteristics of deep-sea polymetallic nodule mining system have been analyzed. Among all disturbances, c o l le c t in g head an d c o l le c t in g m a c h in e have been found make the biggest impact on the marine environment, w h o s e a c t io n s m a k e th e seabed s e d im e n t disturbed,migrated and diffused. According to the technical parameters of the mining machine and its working methods , sediment disturbance model has been establ ished. Fluent sof tware has been used to simulate the disturbance on sediment,DPM model has been used to track particle motion,and concentration has been calculated. The numerical simulation shows ： A lo n g w i t h th e p o lym e ta l l ic n o d u le mining , marine sediments are disturbanced into submarine water,form particle clouds behind thedisturbance source,then form particle clouds in front of the disturbance source. With the clouds diffuse ,the number of clouds lessenes, th e s e d ime n t c o n c e n t ra t io n in c lo u d s a ba te s, th e c h a n g e o f c o n c e n t ra t io n becomes even after 30 min when disturbance source stopped. Which can provide the monitoring parameters for the follow-up seabed mining,and the basis of the monitoring sensors layout.