Techniques for predicting the maximum uplift forces which may be applied to direct embedment anchors without causing the anchor to pull out are provided. This holding capacity problem is subdivided into three categories: immediate breakout, long-term static load, and long-term repeated load. Holding capacities under long-term repeated and long-term static loading conditions are poorly understood at present. It was therefore necessary to combine work from other areas with a small amount of directly applicable work to yield approximate immediate use results. For each manner of loading considered, two general types of seafloors are considered: cohesionless and cohesive soil. Rock is not considered in this report. (Author).

This report provides interim guidelines for designers of dynamically loaded seafloor foundations and anchors based on available knowledge of terrestrial and seafloor soils. Investigations of the response of selected seafloor soils to dynamically induced forces are reported, and the development of standardized design procedures for propellant-actuated direct embedment anchors is presented. These procedures must account for the strength of seafloor soils over the short and the long term around a seafloor embedment anchor sustaining static and dynamic loads. Important findings were that the soil parameters relevant to the holding capacity of deeply embedded propellant-actuated anchors are: soil moduli, creep, suction, cyclic strength loss, stress-strain relationships under dynamic loading, and responses to shock and slow loading. Some anchor-related parameters are: (a) the anchor embedment depth, buoyant weight, angle-of-line pull, and size and shape of flukes; and (b) magnitudes of the static and dynamic components of loading and the dynamic loading period for loads produced in the line by current fluctuations, waves, vortex shedding, impact, or line snap, and for loads produced more or less simultaneously in the line and the sediment by earthquakes or underwater blasts. It is recommended that planners use the interim design guidelines in this report for the engineering of embedment anchors to sustain dynamic loading until revised guidelines are developed. Field data from dynamically loaded embedment anchor moorings in actual use and other operating seafloor structures should be collected over extended periods of time for use in verifying and refining the present design methods. Revised guidelines should be available in 1978. (Author).