(Noorany, 1982a). But this reduction alone cannot fully explain the 

 extremely low pullout resistance values of piles in calcareous sand. It 

 is reasonable to postulate that grain crushing also reduces the lateral 

 soil stress on the piles. However, no reasonable design methodology can 

 be established without well-documented, realistic pile-load test data 

 (laboratory and field data). These data should include measurements of 

 axial shear transfer and lateral stress at or near the pile wall. The 

 results of the studies thus far are not sufficient to develop a pile 

 design method. The results do indicate that crushing takes place near 

 the pile wall and has an adverse affect on frictional resistance. The 

 results also clearly indicate that driving resistance is a poor indicator 

 of load capacity. It should be recalled that this (blow count criteria) 

 had been the state-of-the-art design procedure used for the Diego Garcia 

 pier. 



It is apparent that friction capacity of hammer-driven piles in 

 cemented calcareous sands is poor. In order to achieve adequate capacity 

 pile loads will have to be either transferred to the pile tip or trans- 

 ferred by friction, probably by using a pile installation method that 

 can develop friction capacity. 



Alternate Pile Concepts 



The conceptual piling systems are different from conventional piling 

 systems to varying extents. These systems and their effectiveness in 

 improving load carrying capacity in calcareous sediments still need to 

 be verified. In addition, most of the procedures and equipment required 

 for deploying these "improved" piling systems need further development. 



After further development and confirmation tests (either in the 

 laboratory by centrifuge tests or in the field) , some of these developed 

 systems may be more applicable to certain types of calcareous sediments 

 than others. It is anticipated that various systems might work well in 

 certain calcareous sediments but not well in others. The ultimate goal 

 is to achieve the ideal scenario that the pile makeup will consist of 

 various standardized segments and features arranged to maximize its load 

 carrying capacity in any specific type of calcareous sediments. 



These systems have not been evaluated for the Navy's missions and 

 capabilities. Some of the systems might be discarded for operational 

 reasons. Certainly the complexities of installing these piling systems 

 make the simplicity of hammer-driven pipe piles attractive. 



CONCLUSIONS 



In general the state of knowledge of the engineering behavior of 

 calcareous sediments is meager and the understanding of pile behavior in 

 calcareous sediments is even less. However, improvements are being made. 

 The work reported herein adds to the knowledge on frictional behavior, 

 the processes occurring near driven piles, and the frictional resistance 

 of driven piles in calcareous sands. 



The complexity of the depositional process, grain-structure arrange- 

 ments, discontinuities, and post-depositional alterations dictate that a 

 significant spatial variation in composition and behavior of calcareous 



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