ERTEC Program 



In an effort to correlate the findings from this study with those 

 from previous studies, ERTEC 's work was developed around varying void 

 ratios and cementations, and driving a model pile into two different 

 sands. The objective of this investigation was to qualitatively examine 

 the following items related to piles in calcareous sands: 



• The effect of pile driving on the degree of grain crushing. 



• The effect of grain crushing on the frictional resistance 

 characteristic of piles in calcareous sands. 



• The effect of cementation on the crushability and frictional 

 resistance characteristics. 



The test setup and equipment used for this investigation were spe- 

 cifically designed and built to meet the project goals. Figure 22 is an 

 illustration of the complete test setup. The test setup consisted of 

 the following systems: 



• Model pile and pile driving stem 



• Sample retention system (red barrel) 



• Sample preparation system 



• Pullout load test system 



• Instrumentation and data acquisition system 



The model pile and the driving assembly was the same as that used 

 in the NCEL program, i.e., a 1-1/2-inch diam pile driven into the sand 

 by free weights falling through a guide rod and impacting on top of the 

 pile. The sample was placed in a 30-inch diam by 30-inch high, hollow 

 steel cylinder test drum with end plates bolted to both ends of the 

 cylinder. The test drum was equipped with a pressurization system that 

 could apply up to 100 psi pressure to simulate overburden and lateral 

 stress conditions. For this study, an overall confining pressure of 

 20 psi was applied in every test, simulating a pile driven about 50 to 

 60 feet below the seafloor. The pullout load test included a hydraulic 

 loading system and load frame. The hydraulic system consisted of a 

 hydraulic actuator, a hydraulic pump, and a flow rate adjuster. This 

 system was used to pull out the pile at a slow rate. 



Test Procedures 



A total of 20 laboratory tests were performed on the two different 

 sands prepared at different densities, moisture contents, and cement 

 contents. Each test was done in the following sequence: 



15 



