全海深沉积物保压取样装置设计及试验研究

Design and Experimental Study of Pressure-retaining Sampling Device for Sediments in Hadal Trenches

为了实现全海深沉积物保压取样,提出基于着陆器的自密封式全海深沉积物保压取样系统。取样系统主要由深海充油电机、传动机构、取样机构、保压筒、蓄能器、压力传感器和多个高压针阀及不锈钢毛细管组成。为取样器在海底自主取样提供动力,设计了专用于深海超高压的水下电池。整套装置总重60 kg,其中,水下重量45kg。通过设计花瓣压缩环形取样、下端自封闭、两端自平衡的新型取样机构,简化了装置的结构,减轻了装置重量。通过对取样器贯入过程的分析和计算,得到最大贯入力的值为786.5 N。搭建了贯入试验台架以模拟沉积物的取样过程,在不同性质的黏土中测试取样器的取样能力和贯入力,试验结果与计算结果相符合。对于硬塑性、塑性和流塑性3种黏土,取样器的取样体积分别为410、120和20 mL,最大贯入力分别为720、210和20 N。为验证取样器保压筒的密封性能和强度,进行了110 MPa内压试验,保压120 min无压降。为验证取样器在高压下的工作稳定性及保压性能,在60 MPa和100 MPa高压舱内进行了多次测试,试验结果表明,60 MPa下保压率超过90%,100 MPa保压率超过88%。最后,在中国2021大洋科考TS21航次中,取样器搭载“奋斗者号”载人潜器在西菲律宾盆区和马里亚纳海沟进行了3次原位测试,所提出的取样器均完成保取样任务,保压率超过80%,共获取保压沉积物样品超过700 mL。

To realize pressure-retaining sampling of deep-sea sediments, a self-sealing all-depth oceanic sediment pressure retaining sampling system based on the lander is proposed. The sampling system comprises a deep-sea oil-filled motor, transmission machinery, sampling machinery,pressure holding cylinder, accumulator, pressure sensor, multiple high-pressure needle valves, and stainless steel capillary. In addition, an underwater battery dedicated to ultra-high deep-sea pressure is also designed to power the sampler for autonomous sampling on the seabed. The total weight of the equipment is 60 kg, and the underwater weight is 45 kg. The structure of the device is simplified, and the weight is reduced by designing a new sampling machinery with petal compression ring-shaped sampling, self-sealing at the lower end, and self-balancing at both ends.Through the analysis and calculation of the penetration process of the sampler, the value of the maximum penetration force is 786.5 N. A penetration test platform was built to simulate the sediment sampling process, and the sampling ability and penetration force of the sampler was tested in clays with different properties. The test results were consistent with the calculated results. For the three clays of complex plasticity, plasticity, and fluid plasticity, the sampling volume of the sampler is 410 mL, 120 mL, and 20 mL, respectively, and the maximum penetration force is 720 N,210 N, and 20 N, respectively. To verify the sealing performance and strength of the pressure-retaining cylinder of the sampler, an internal pressure test of 110 MPa was carried out. The pressure was maintained for 120 minutes without pressure drop. To verify the working stability and pressure retaining performance of the sampler under high pressure, several tests were carried out in 60 MPa and 100 MPa high-pressure chambers.The test results showed that the pressure holding rate was over 90% at 60 MPa and over 88% at 100 MPa. Finally, in the TS21 voyage of China’s2021 oceanic scientific expedition, the sampler carried by the “Striver”, a manned submersible, for three in-situ tests in the West Philippine Basin and the Mariana Trench, and the proposed samplers all completed the preservation sampling task. The pressure-retaining rate exceeded 80%, and a total of more than 700 mL of pressure-retaining sediment samples were obtained.