The drag force in each stage can be differently derived as below。

In the 1st stage, most of drag forces are caused by friction between anchor and soil and the equation (1) can be used as a drag force equation。

F1, F2=N1·  (W+C·Wadd) (3)文献综述

N1 : Bearing capacity factor of stage 1

W : Weight of anchor

Wadd : Weight of sand accumulated over the fluke (Wadd = (Af·Lf·ρg·sinθ1) / 2)

C : calibrating constant, including soil heave effect

γ  : Specific weight of wet soil (γ = ρg)

On the 2nd stage, most of drag forces are caused by soil resistance on the failure wedge surface and the equation (2) can be used as a drag force equation。

F3=F2+N2·Af·ρg·d (4)

N2 : Bearing capacity factor of stage 2

A : Fluke area

d : Depth of fluke

By applying the test results to Eqs。 (3) and (4), bearing capacity factors of each stage are derived as in Tables 7~8。

Table 7 Bearing capacity factor (sand)。

TYPE W (kgf) N1 C N2

HALL 6000 0。79-0。82

1。2 9。75

9350 0。71-0。75 10。60

12300 0。90-0。96 8。18

AC-14 4500 0。70

1。6 5。91

6975 0。70 5。23

9225 0。71 6。55

POOL-N 6975 1。01-1。05

1。8 5。00

9225 0。90-0。93 5。21

Table 8 Bearing capacity factor (mud)。

CONCLUSIONS

This study is carried out to verify the drag embedding motion and the resultant holding force of three types of anchor models (HALL, AC-14, POOL-N) on both hard(mud) and soft(sand) seafloor, and to derive governing equations, regarding the relations of the anchor geometry and the holding force。

Considering the test results, the anchor  embedding motion is persified by three stages with different kinds of motion and force applied and, finally, the governing drag force equation in each stage is derived with respect to the anchor geometry and the embedded depth on both hard and soft seafloor, using the bearing capacity factor。

The results can be used to verify the actual holding capacity of each type of DEA, as reference, and be used as fundamental data for the development of more efficient and higher performance DEA in the future。

ACKNOWLEDGEMENT

This work was supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy。 (No。 20114030200050 )文献综述

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