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First In-situ Full Deep Sea Sediment Strength Testing Device: MEGE
Guan Yang, Hongxian Shan, Tingkai Nian, Jingxi Liu, Yongfu Sun, Zexiao Xie, Chaoqi Zhu, Xiaolei Liu, Yupeng Song, Jianye Sun, Jingqiang Wang, Baogang Li, Xing Wang, Hao Zhou, Na Zhu, Yongzheng Quan and Yonggang Jia

The development of ocean resources and ocean engineering construction has gradually advanced into the deep sea. However, precise measurement of the shear strength of seabed sediments remains a challenge. To obtain the strength of seabed sediments, an in-situ device for testing the mechanical properties of seabed sediments has been developed. This device can obtain the strength of the shallow sediment layers at a site by measuring the penetration resistance and pore water pressure and by collecting sediment samples. The device mainly includes a device carrying and penetration system, a control and communication system, and a seabed sediment mechanical property measurement system. The maximum designed working depth is 11,000 m, the maximum penetration depth is 1.3 m, and the penetration force is 2.4 kN. A large number of in-situ tests have been carried out in harbors and shallow sea areas, and rich measured data have been obtained. The measurement results show that the strength of the soil in the harbor is less than 1 kPa at depths of 0–0.5 m, i.e., ultra-soft soil, and the average strength of the soil at depths of 0.5–1.2 m is 1–5 kPa. The strength of the shallow sea soil is basically 0 kPa in the depth range of 0–0.18 m, and then it gradually increases with depth, finally stabilizing at around 3 kPa. The device overcomes the problem that it is difficult for a single probe to accurately measure the mechanical properties of seabed surface sediments, and accurate measurement of the mechanical properties of seabed surface sediments can be attained. This device can provide support for future ocean resource development and engineering construction.

Keywords: static cone penetration test, full-flow penetrometer, deep-sea sediments, undrained shear strength, Vane shear

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