sediments can exist within a very small distance. The most significant 

 parameters affecting the behavior of calcareous soils seem to include 

 (1) carbonate content, (2) grain crushability and associated volumetric 

 changes, (3) degree of cementation, (4) index properties, and (5) geo- 

 logic process. Several relevant behavior aspects of calcareous soils 

 are summarized as follows: 



• Soil is softer and more compressible after grain crushing and 

 volumetric change induced by confining or shearing stresses. 



• Friction angles decrease with increasing confining pressure. 



• Friction angles are higher than or similar to the values for 

 terrigenous soils, before being crushed. 



Long, open-ended, steel-pipe piles are used for nearshore and off- 

 shore applications. Installation techniques include: (1) driving by 

 impact hammer, (2) drilling and grouting, and (3) driving by vibratory 

 hammers. A review of the state-of-the-art and the alternate pile sys- 

 tems suggests that the open-ended, pipe piles is still a popular solu- 

 tion to foundation problems in calcareous soils. 



Present design methods rely heavily on either empirical approaches 

 or expensive field pile load tests. Further work and a better under- 

 standing of pile-sediment interaction mechanism of piles in a calcareous 

 sediment is necessary to develop improved design methods. 



FINDINGS 



1. Calcareous sands exhibit higher friction angles than silica sands. 



2. The high friction angles of calcareous sands are not the result of a 

 dilatent behavior. 



3. The friction angles of calcareous sands decrease with increasing 

 confining stress. 



4. The friction angles of calcareous sands and the angles between cal- 

 careous sand and steel are not changed by grain crushing. 



5. The friction angles between calcareous sands and steel are comparable 

 to silica sand and steel. 



6. Calcareous sands are more compressible than silica sands. 



RECOMMENDATIONS 



1. Continued laboratory work is needed for developing a rational design 

 methodology for installing piles in calcareous sands using the large 

 drum described above. The work needs to determine contributions to total 

 pile resistance from end bearing and side friction and the shear transfer 



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