skin frictions that would also lead to higher predicted skin friction. 

 These procedures have not found favor because of the uncertainty in de- 

 signing piles in calcareous soils. 



The design of drilled and grouted piles in calcareous sands appears 

 to be so site-specific that recommended design parameters do not appear 

 in the literature. The lack of progress in the development of general 

 design procedures is undoubtedly due to the limited amount of experi- 

 mental work. 



Empirical Correlation With Resistance To Driving . The empirical 

 correlation approach correlates the driving resistance to the axial capa- 

 city of piles in accordance with an empirical formula. A variety of 

 these formulas are available, among them is the Engineering News Record 

 formula: 



W U H = R (S + 0.1) (2) 



H 



where: W = weight of the driving ram 



H = distance of the ram travel 



R = resistance of the pile to driving 



S = distance the pile tip penetrates the soil 



Each of the formulas equate the driving energy with the resistance the 

 soil offers to pile penetration. This approach was used in the pier 

 constructed at Diego Garcia. Based on Equation (2) , the determined shear 

 strength property from selected soil samples and a pile load test, a 

 blows per foot criteria for pile driving procedures and the estimated 

 pile embedment depth was established to reach the designed pile capacity. 

 The estimated depth was about 65 feet. Based on the unpublished pile 

 driving record, many of the piles required two to three times this depth 

 to meet the blow count criteria. The results of the work at Diego Garcia, 

 therefore, indicated that the driving resistance is not a good indication 

 for predicting pile capacity in calcareous soils. 



Correlation With In-Situ Penetration Tests . Standard penetration 

 resistance has been used for calculating pile capacity in chalk. As 

 indicated in Figure 1, this correlation yields a wide scatter of results. 

 In addition SPT results are not reproducible and as a result this method 

 must be used with caution. 



Full-Scale Pile-Load Test . The in-situ, full-scale pile-load test 

 is the best method for taking site-specific parameters into consideration. 

 However, calcareous sediments vary significantly in composition and engi- 

 neering behavior between nearby locations and is difficult to extrapolate 

 results. Thus, the number of pile load tests required for calcareous 

 soils may be larger than for terrigenous soils. This can be very costly. 

 Research and development in understanding soil-pile interaction might 

 reduce the number of tests required. 



