The in-situ shearing strength and penetration resistance testing of the soft deep seabed sediments were conducted at 41 sites in Chinese Pioneer Area in the eastern part of the Pacific Ocean. According to the measured values, the shearing strength and penetration resistance values show the similar trends that increase with testing depth till to their own peak values and then go down in small range. The maximal shearing strength and penetration resistance values are observed in the depth of 36.9cm, respectively, 14.8kPa and 76.3kPa. The sediments at the depth of 14 ~ 20cm can be used to track and bear the tracked vehicle because of its homogeneous mechanics characteristic with the uniform shearing and bearing performance. According to the measured values, four empirical formulas on shearing strength vs. testing depth, penetration resistance vs. testing depth, shearing strength vs. penetration resistance and penetration resistance vs. bearing capacity are founded. And the measured values and founded empirical formulas can be used as the academic basis for the design and optimization of the seabed tracked vehicle.

INTRODUCTION

Chinese Ocean Polymetallic Nodules Pioneer Area (COPNPA) lies to the west of Pacific Basin(C-C zone) and includes eastern part and western part (Lv WZ, et al,2001). The physics and mechanics properties of deep seabed sediments in the western part of COPNPA(the north latitude 7°~12° and west longitude 141° ~ 149°) is rather different from that of land soil with big void ratio, high water content and small cohesion. Especially, the upper layer of soft deep seabed sediments was in the state varying from flow to flow plastic then to plasticity. Research shows that seabed tracked vehicle is a better seabed working vehicle to travel and collect the deep-sea polymetallic nodule on soft deep seabed sediments for its remarkable traction and bearing performance (Li L and Chen XM, 2001).

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