of differential settlement were presumed to occur before the systems were 

 locked. The locking process prevented subsequent movement due to current 

 drag. At another range, a simple spread footing slid down a shallow slope 

 (Linger, 1969). This problem was prevented on later foundations by using 

 footings with cutting edges designed to key the footing into the underlying 

 soil and, thereby, prevent lateral movement. 



More recent trends in structural design have been toward the use of 

 simpler configurations. This change was facilitated to a degree by advances 

 in fields related to range design and layout. The change has resulted in the 

 use of lower total weights and larger widths on the footing systems. This 

 more recent and now somewhat standardized design, the ring footing, has 

 experienced no known foundation performance difficulties during use in 

 several diverse soil types. 



The following sections summarize the characteristics of several 

 acoustic ranges. Information includes structural aspects (size, weight, con- 

 figuration) of the system, environmental data (soil parameters, depth of 

 water, currents, terrain) at the site, and performance (settlement, sliding) of 

 the structure with respect to foundation behavior. Data on the systems were 

 generally sketchy; therefore, only an empirical performance investigation can 

 be attempted. 



AUTEC Range. The Atlantic Undersea Test and Evaluation Center 

 (AUTEC) was completed in early 1967 (Jackson and Grant, 1967; Busby, 

 1965 and 1969; Covey, 1967; Austin, 1964). In addition to providing three- 

 dimensional tracking, the range conducts temperature, salinity, and pressure 

 measurements. AUTEC is located about 180 miles southeast of West Palm 

 Beach, Florida, in the Tongue-of-the-Ocean (TOTO) — a sheltered expanse 

 of water parallel to Andros Island in the Bahama Islands. The body of water 

 is approximately 100 nautical miles long by 15 nautical miles wide and has a 

 depth which varies from 3,600 feet in the south to 6,600 feet in the north. 



The tracking system is composed of weapons, acoustic, and sonar 

 ranges. The Weapons Range occupies an area 5 miles wide by 35 miles long 

 off the southern end of Andros Island. Three-dimensional tracking is pro- 

 vided by 55 individual hydrophones geometrically arranged into two separate 

 groups at opposite ends of the range. The Acoustic Range is located between 

 the Weapons Range and New Providence Island. Two hydrophones occupy 

 this 5- by 5-mile area. The Sonar Range, scheduled for later completion, 

 will include sonar transponders accurately located on the seafloor. 



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