Investigation of Anchor Systems for the Mobile Aircraft Arresting System (MAAS)

摘要

Four soil test sections were used to evaluate the performance of the cruciform earth anchors used with the Mobile Aircraft Arresting System. Two test sections were constructed with a plastic clay material, one with a silt and one with an in situ silt. Basic anchor tests consisted of driving a single anchor, double anchors, triple anchors, and twin-triple anchors 1,2,3, and 4 ft deep. The rate of anchor penetration under the action of a hydraulic driver was recorded in ft/sec. Horizontal movement of anchors under load, type of damage to anchors and ancillaries, and surface soil disturbed during the tests were noted. Plots of the force in pounds required to remove or damage anchors versus soil strength (California bearing ratio or CBR) obtained in the plastic clay and silt subgrades are presented. The data in the plastic clay indicate that as the CBR increased, the force required to remove the anchor(s) increased. This trend was not evident in the silt sections as one section was an in situ (7CBR) and the other was a constructed ans remolded (2.5 CBR) section. For a valid comparison, a 7 CBR section should be constructed, and the results of the two remolded soil test sections should be compared to check for a similar trend as with the plastic soil test sections. The data also indicate that the force to remove or damage anchors increases as the anchors are driven deeper into the soil, and the force increases as the number of anchors in a cluster increases.