of several different analytic techniques, and (4) recommend the 

 technique which predicts the measured data best. 



APPROACH 



The approach used in this in situ testing program was first to 

 acquire previously developed accelerometer , penetrometer, and coring 

 equipment. Second, a two day cruise aboard a Navy YFU was conducted, 

 soil cores were taken, and free-fall cone penetrometer tests 

 performed. The accelerometer was mounted on the equipment during 

 both operations thereby allowing all tests to be utilized as penetration 

 tests. Two test sites in the Santa Barbara Channel off Southern 

 California were investigated. Next, the soil samples obtained were 

 subjected to a series of laboratory index property and shearing 

 resistance tests. The accelerometer records were reduced and a 

 preliminary analysis was performed. Two analytic techniques were 

 used: (1) a regression analysis of the accelerometer records was 

 performed in an attempt to derive soil property information and 

 (2) the measured soil property information was used in a physical 

 analysis in an attempt to synthesize the accelerometer records. 

 Conclusions based on these analyses were drawn, and recommendations 

 for future investigations were developed. 



TEST EQUIPMENT 



The acceleration data used in this penetration investigation 

 were acquired with a Scott Accelerometer, developed for use in 

 analyzing the behavior of seafloor gravity corers.' The accelerometer 

 is a self-contained unit which is mounted atop a corer or penetrometer 

 to measure the acceleration of the package. The main components 

 are batteries, a governed motor, a rotating drum, and a moving stylus 

 (see Figure 1). The motor rotates two components: the drum and a 

 worm gear. The worm gear gives the stylus a downward motion parallel 

 to the axis of the drum. A piece of recording paper is fastened to 

 the drum and the paper is marked by the stylus. Consequently, the 

 marked line reflects two motions, the drum rotation and the stylus 

 motion parallel to the drum axis. However, the rotating drum is 

 mounted on a spring and damper . The drum represents the mass in a 

 spring-mass-damper system where any net acceleration on the drum 

 would result in a commensurate motion. Therefore, in the case of 

 zero net acceleration (constant velocity) , the marked line would be 

 a result of drum rotation and stylus motion, solely, and would have 

 the form of a simple helix. In the case of non-zero acceleration 

 (changing velocity) , the drum would also move on its spring-damper 

 supports and the marked line would deviate from the form of a helix. 

 This deviation is a measure of the acceleration. 



